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How Fast Do Commercial Planes Fly?

[File photo: Adobe Stock]

Over the past few decades, transportation technology has advanced tenfold, but why aren’t airplanes going any faster? Turns out, there’s a few very good reasons as to why you don’t want your commercial flight to travel at supersonic speeds—turbulence, energy costs, and ticket prices could all be affected by your flight’s speed. Let’s dive into why your commercial flight keeps a normal pace.

Pass the Test. Take to the Skies

What Is a Commercial Plane?

Commercial airplanes are non-military aircraft suited to carry passengers and/or freight between airports.

What Impacts the Speed of a Plane?

When talking about aerodynamics, there’s a plethora of factors that affect an aircraft’s speed. In short, here are three important components to airspeed.

Air pressure decreases at higher altitudes, allowing aircraft to move at a higher speed.
Airplanes can travel faster when flying in the same direction as the wind. Conversely, an airplane will fly slower (and use more fuel) when flying into headwinds.
Of course, an airplane’s overall speed depends on how much thrust is produced by the engines. Not all commercial jets are made equal.

How Do You Measure an Airplane’s Speed?

An aircraft’s speed, known as airspeed, is typically measured in four different ways. No matter which type you use, all airspeed is represented in knots.

Indicated airspeed is measured using the aircraft’s pitot tube and static pressure. This measurement is displayed on the pilot’s airspeed indicator, which may be a separate gauge, or as part of a primary flight display or PFD.
True airspeed measures the speed of the aircraft in relation to the surrounding air. As you reach higher altitudes, the IAS will become less accurate, because of lower ambient air pressure.
Groundspeed measures the aircraft’s speed in relation to a single point on the ground. Technically, GS is true airspeed corrected for wind.
Calibrated airspeed is calculated using indicated airspeed corrected for any measurement errors. CAS is particularly useful at lower speeds.
This type of measurement is generally reserved for jets—and aircraft capable of reaching the sound barrier. Mach can be found by dividing the speed of the aircraft by the speed of sound. That being said, the speed of sound varies at different air pressures.

Maximum Speed for Popular Airplanes

Just like cars, airplanes have speed limits in certain areas. While today’s commercial airplanes won’t take you across the Atlantic Ocean in less than a few hours, most major airliners travel at decent speeds.

Boeing 747: 614 mph
Boeing 737: 588 mph
Airbus A380: 737 mph

Different Speeds of Flying

Just like any other type of vehicle, your speed largely determines what maneuvers you can accomplish. For airplanes, certain speeds are absolutely necessary to carry out a safe transition from ground to air.

At takeoff, the average speed of a commercial airplane is anywhere between 160 and 180 mph (140 to 156 knots).

For most commercial airliners, the airplane’s cruising speed ranges between 550 and 600 mph (478 to 521 knots).

While landing, speed is largely affected by the aircrafts current weight, commercial airplanes typically land between 130 and 160 mph (112 to 156 knots).

Speeds of Different Aircraft Types

Outside of commercial aviation, airplanes come in a great variety of different use types— some much faster than others.

Private Jets

Private jets can fly at speeds anywhere between 400 and 700 mph (348 to 608 knots), similar to commercial airplanes. Given their smaller size, they generally can’t fly as far as their larger counterparts because of fuel storage constraints. But a handful of ultralong-range jets can fly more than 8,000 miles or 6,952 nautical miles.

Military Airplanes

Military aviation is just as diverse as the rest of the industry. Military aircraft are designed with specific goals in mind, such as surveillance, assault, or cargo transport. Instead of listing the top speed of every military aircraft, here are a few examples from different categories:

Lockheed Martin C-130J (Cargo): 416 mph
Lockheed Martin F-22 (Fighter): 1,500 mph
Boeing KC-135 (Air Refueler): 580 mph
Northrop Grumman B-2 (Bomber): 628 mph
Northrop Grumman RQ-4 (Surveillance): 391 mph

Single Engine

Single-engine airplanes, such as the Cessna 172, fly considerably slower than commercial airplanes. For the typical single-engine plane, you’ll be able to fly around 140 mph (122 knots). However, some of the more advance single-engine airplanes, like the Pilatus PC-12 NGX, have a top speed of 334 mph (290 knots).

Different Speeds, Different Goals

Commercial airplanes, while heavy and large, are capable of reaching high speeds over extended distances. While no two planes are exactly alike, physical limitations keep most airliners in the same playing field.

Outside of commercial aviation, the variety of aircraft fosters a variety of top speeds—ranging from a comparably slow Cessna 172, to a supersonic F-22. Either way you fly, make sure you land with FLYING Magazine .

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Simple Flying

How fast do passenger planes fly.

Ever wondered how fast you travel through the skies?

Air travel is the safest and fastest mode of transport, preferred by over four billion people annually.
Passenger planes have different cruising speeds, with an average range of 500–521 knots (575-600 mph).
The Concorde was the fastest-ever commercial passenger aircraft, reaching speeds of 1,350 mph (Mach 2).

Air travel remains the safest and fastest mode of commercial passenger and cargo transport, making it the preferred choice for over four billion people traveling around the world annually.

The design of passenger planes has come a long way over the years, with aircraft becoming safer, faster, and more fuel efficient. An aircraft's speed critically affects travel time, fuel efficiency, and overall flight performance. With that said, let us examine how fast passenger planes fly.

Average speeds

If you've frequently flown on a certain route with different aircraft, you may have noticed that the time it takes to fly from your departure to your destination airport often differs. While this may be affected by other aspects like weather conditions and the flight path followed, the difference in cruising speeds among commercial planes also plays a part.

Various commercial aircraft types are in service today, from the DHC Dash 8-Q400 turboprop to the Airbus A380 superjumbo. They all have different cruising speeds and typically travel faster at higher altitudes. On average, passenger planes have a cruising speed of 500 to 521 knots (575-600 mph), about Mach 0.78 to 0.81. Private jets travel at 435 to 521 knots (500-600 mph), about Mach 0.68 to 0.81.

Types of speed measurements

The speed of an object moving on the ground, like a car, is calculated slightly differently from an object moving in the air, like a plane, because of the long distances covered by the flying object and the different forces acting on it. There are two main types of aircraft speeds: ground speed and airspeed.

Find out why airspeed is measured in knots here

Ground speed is the time taken by the aircraft to cover a certain distance over the ground. At about 35,000 ft, a passenger plane can have an average ground speed of around 300–600 knots. While commercial aircraft may cruise at almost similar airspeeds, the headwinds and tailwinds typically affect the speed at which it passes over the ground.

On the other hand, airspeed is the aircraft's speed relative to the air around it and is the preferred measurement in aviation. Furthermore, indicated airspeed (IAS) and true airspeed (TAS) are among the most common conventions for determining airspeed.

IAS is the speed shown on the airspeed indicator, uncorrected for instrument errors and atmospheric conditions. TAS is the actual speed of the aircraft relative to the atmosphere, independent of instrument errors and other conditions. It is, therefore, the speed used in most aircraft descriptions and manuals.

The fastest commercial planes

When aircraft fly at about 25,000 to about 30,000 ft, their speeds are referenced as a percentage of the speed of sound (Mach). The speed of sound (Mach 1) is about 761 mph at sea level and an air temperature of 59 °F (15 °C). Below are some of the fastest commercial aircraft in service today:

Airbus A350-1000

In addition to being one of the most fuel-efficient passenger aircraft, the Airbus A350-1000 is one of the fastest. It has a top speed of nearly 683 mph (Mach 0.89).

It first flew in 2017 and entered commercial service in 2018, becoming a popular model for several carriers. There are over 79 active A350-1000s in service, with about seven carriers. Furthermore, an additional 161 have been ordered by 15 airlines.

Boeing 747-8i

The Boeing 747-8i is also among the fastest commercial aircraft. It can reach speeds of 660 mph (Mach 0.86). It is the longest-range version of the 747 family, and as it is no longer in production, it is only in operation with a few carriers.

Boeing 787 Dreamliner

With its different variants, the Dreamliner can fly faster than most passenger aircraft on the market today. It is capable of flying at 690 mph (Mach 0.9), making it one of the fastest jetliners. The 787 family is operated by over 39 different carriers.

Fastest-ever passenger aircraft

The fastest-ever commercial passenger aircraft, the Concorde , comes as no surprise. The aircraft had a cruising speed of 1,350 mph (Mach 2), up to 60,000ft. It made its fastest transatlantic crossing on February 7, 1996, when it flew between New York and London in 2 hours and 52 minutes.

While there are currently no commercial or private jets carrying passengers at those speeds today, there are also a few other notable mentions. The Dassault Falcon 7X, Gulfstream G700, Cessna Citation X, and Bombardier Global 8000 are among the fastest private and business jets in operation.

Did you know exactly how fast passenger planes fly? Have you ever flown on any of the world's fastest aircraft? Please let us know in the comments!

Sources: Aerotime , Flight Deck Friend

Why Do Airlines Use Knots Instead Of Miles Per Hour?

Resident pilot 121pilot , a captain for a major U.S. airline, authors a new column on Live and Let’s Fly called Ask Your Captain . His mission: demystify the flight deck and an answer any question you may have on the topic of flying.

Q: What’s the relationship between knots and MPH and why do airlines use knots?

A: This goes back almost to the dawn of flying and is connected to the nautical roots that many airlines have. A nautical mile is equal to one minute of latitude or 6,076 feet vs a statute mile at 5,280 feet. When your navigating using charts, the use of nautical miles because of its relationship to latitude makes navigation a lot easier. This is why ships and airliners use nautical measurements. This is a lot less relevant in today’s world of glass cockpits, and GPS where we aren’t taking sights with a sextant or plotting our position on charts like they did in the old days. But because it’s the convention, it’s still what’s used. If you want to convert knots (a knot is a nautical mile per hour) to MPH the conversion is 1 knot equals 1.15 MPH.

Q: Do you need perfect vision to fly commercial jets? Where do you learn: flight school or the Military? Do the airlines favor one or the other? Do you have to pass a physical and how often? Are there regular drug tests?

A: No, you don’t need perfect vision to fly commercially it just has to be correctable. Commercial airline pilots come from a variety of sources both civilian and military. The advantage military pilots have is that, at least for the fixed wing guys, most of them can get hired directly by a major and do not need to spend a few years at a regional airline first. I suspect that airlines tend to prefer military pilots for the simple fact is that there aren’t even remotely enough of them to fill the cockpits at US major airlines. Yes, we have to pass a FAA flight physical and hold a class 1 medical. First Officers are required to do it once a year and Captains have to do it every six months. And yes, we are subject to random drug testing.

Have a question for the captain? E-mail him at ask121pilot at yahoo dot com and you may see your question appear in a future column!

About Author

121pilot is a pilot for a major U.S. commercial airline who offers analysis on industry news as well as occasional reflections on his own travels.

How Should A Teenager Prepare To Be A Pilot?

How different is it to fly a narrowbody versus widebody airplane, why do pilots who fly widebodies get paid more.

Knots equal nautical miles per hour. One nautical mile equals 1.15 statute or “regular “ miles. The term knots comes from the maritime traditions. The other relevant speeds are really the Mach speed, which is the measurement of the speed of sound. This varies a lot according to altitude, temperature, air pressure and wind speeds. The other 3 relevant air speeds would be IAS=indicated airspeed, GS=ground speed or how fast you’re going over the ground and TAS=true air speed, corrected for winds. These last 3 are ALL measured in knots.

This is obviously pre 911, but on a Lufthansa flight from Frankfurt to the US, on an A340, I got to sit in the cockpit for about 15 minutes as we were crossing the Atlantic. First off, what a view! I remember them telling me LH typically didn’t like to hire military pilots, because of a fighter jock mentality. Commercial flying from point A to B was too tedious for many of them. Things have likely changed since then,

I know!! It was great wasn’t it!? I got a chance to fly on LH as well from Frankfurt to Washington Dulles pre 9/11. It was a 747-400 back then and yes, they let me visit up there for almost an hour. It was out of this world !!

@David – I think LH’s continued preference for non-military pilots stems from the fact that most German military pilots on fixed wing aircraft are flying fighter jets, which is indeed very different from flying a passenger jet from A to B. Also, fighters often have only 1 pilot and 1 non-pilot crew (gunner/technician), so fighter pilots have often been trained to go it alone from the start of their career, unlike LH’s own pilots which are firmly inducted into the Multi-Crew mindset. It may thus be a different mindest indeed. However, military pilots flying transports, like the Transall, the A400M or the Airbus / Bombardier fleet of the Luftwaffe may be more suitable for commercial passenger aviation though, given their multi-pilot cockpit environments and a generally more “slow & steady” approach to flying compared to fighters.

Speaking a guy who flies with a lot of ex single seat fighter pilots I’ve never met one who gave me any cause to question their suitability to operate in a multi pilot airline environment. If LH won’t hire guys just because they spent 20 years in a single pilot fast jet they are being extremely short sighted.

Why are they called knots? Here is why and I quote: “ Until the mid-19th century, vessel speed at sea was measured using a chip log. This consisted of a wooden panel, attached by line to a reel, and weighted on one edge to float perpendicularly to the water surface and thus present substantial resistance to the water moving around it. The chip log was cast over the stern of the moving vessel and the line allowed to pay out.[6] Knots tied at a distance of 47 feet 3 inches (14.4018 m) from each other, passed through a sailor’s fingers, while another sailor used a 30-second sand-glass (28-second sand-glass is the currently accepted timing) to time the operation.[7] The knot count would be reported and used in the sailing master’s dead reckoning and navigation. This method gives a value for the knot of 20.25 in/s, or 1.85166 km/h. The difference from the modern definition is less than 0.02%.”.

MPH would be stupid, they should at least use km/h which is the unit the majority of humans use.

“A nautical mile is equal to one minute of latitude.”

Thanks so much for this tidbit! Best thing I’ve learned today by far.

Save my name, email, and website in this browser for the next time I comment.

What is KTAS? (Knots True Air Speed)

When driving in a car or by train you measure your speed in either miles per hour (MPH) or kilometers per hour (KPH). When traveling by plane, the speed at which you measure is a bit different, pilots use Knots True Airspeed (KTAS).

What is a Knot?

Also known as a nautical mile, knots are measurements that planes and ships use to measure speed. One Knot per hour equals 1.15 miles per hour. The reason for using a different method of measurement is because both boats and planes measure distance using latitude and longitude. To place it in a different perspective, one Knot is one minute, of an arc, on any line of longitude.

One Knot is equal to:

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1 Nautical Mile per hour
1.852 Kilometers per hour
0.514 Meters per second
~1.1507 Miles per hour

Why Are They Called Knots or KTAS?

Before any form of modern measurement was invented, sailors would drag ropes behind their ship. This rope had knots on it, and they used it to measure speed. Now, in modern times, knots are a uniform way for pilots and other industry professionals to have a standardized, as well as international, method of measuring airspeed and travel.

Learn More: Why Do Private Jet Charter Flights Avoid the Sea

KTAS vs IAS

Knots True Airspeed (KTAS) is different than indicated airspeed. KTAS does not take pressure into account. Indicated airspeed (IAS) measures speed along with changes in pressure. Consider KTAS as the speed a plane would be going on the ground, while IAS offers a more accurate measurement in the air. Although KTAS and IAS can be comparable at low altitudes, as the plane rises, IAS is the best measurement to use.

How Does Airspeed Change With an Increase in Altitude?

Typically, true airspeed increases 2% per 1,000 feet increase of altitude. Although this is a general rule, changes in temperature and pressure can allow for a different outcome.

Here are a few examples of indicated airspeed (IAS) versus knots true airspeed (KTAS):

6,700 feet at 125 IAS = 142 KTAS
9,000 feet at 125 IAS = 147 KTAS
10,300 feet at 125 IAS = 150 KTAS
15,000 feet at 125 IAS = 160 KTAS
24,000 feet at125 IAS = 187 KTAS

IAS Increases as Air Becomes Thinner

Essentially, as the air becomes thinner, the IAS increases. If there is no wind, then the faster your true airspeed becomes, the quicker you will reach your destination. Check out the Top Private Jet Airports in the USA and begin planning your next trip.

Why You Should Care About KTAS

Pilots use knots true airspeed to calculate flight plans as well as fuel costs. If you ever plan to fly on a private charter, this will factor into calculating your flight price. Also, for anyone suffering from flight anxiety, it can also help you to feel more comfortable when you fly. Rather than being unsure of how fast the flight is flying, you can feel more secure and in control. This is very helpful in anxiety reduction and can help you to avoid the use of anxiety medications. Learn more about Questions to Ask a Private Jet Company .

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Sometimes fast IS better. From last-minute business meetings, to tight schedules and emergency travel, getting to your destination quickly and reliably is often paramount.

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Flying High: A Guide to Understanding Commercial Plane Speeds

Have you ever wondered how fast commercial planes travel through the skies? As a frequent traveller or aviation enthusiast, understanding the speeds at which these massive machines soar can be fascinating. From takeoff to cruising altitude, commercial planes operate at various speeds, depending on factors such as distance, weather, and aircraft type.

As a captain flying the 737 and an all-around aviation fan, I have researched and compiled a comprehensive guide to help you understand commercial plane speeds better. In this guide, we will explore the different types of commercial planes and their speed capabilities, the factors that affect plane speeds, and the significance of these speeds in air travel.

So sit back, buckle up, and get ready to embark on a thrilling journey through the skies as we delve into the world of commercial plane speeds.

Quick links to what is in this post:

The Different Types of Commercial Planes and Their Speeds

Commercial planes are classified based on their size, range, and speed capabilities. The three main types of commercial planes are narrow-body, wide-body, and regional jets. Narrow-body planes such as the Boeing 737 and Airbus A320 are used for short to medium-haul flights and can travel at speeds of up to 600 miles per hour.

Wide-body planes, such as the Boeing 777 and Airbus A350, are used for long-haul flights and can travel at speeds of up to 650 miles per hour. Regional jets, such as the Embraer E-Jet and Bombardier CRJ, are designed for short-haul regional flights and can travel at speeds of up to 500 miles per hour.

The speed of a commercial plane is determined by various factors, including its engine power, weight, and design. A plane’s maximum speed is usually determined by the manufacturer and is based on the plane’s design and capabilities. Commercial planes are also subject to air traffic control regulations and may be required to fly at specific speeds based on their location and altitude.

Factors That Affect Commercial Plane Speeds

Commercial plane speeds are affected by numerous factors, including weather conditions, air traffic control regulations, and the route flown. Weather conditions, such as wind speed and direction, can impact a plane’s speed and fuel efficiency.

Strong headwinds can slow down a plane’s speed, while tailwinds can push a plane forward, increasing its speed. Air traffic control regulations may require planes to fly at specific speeds to maintain safety and avoid collisions.

The route flown can also affect a plane’s speed, with some routes allowing for faster speeds due to favourable wind conditions. Another factor that can affect commercial plane speeds is the weight of the plane.

An Emirates Airbus A380-800 super jumbo, the largest passenger aircraft in the world is waiting for passengers and loading at London Heathrow terminal 3

The heavier the plane, the more fuel it requires to maintain its speed. Therefore, airlines may restrict the amount of baggage and cargo carried on board to reduce the weight of the plane and improve its speed and fuel efficiency.

The Fastest Commercial Planes in the World

The fastest commercial planes in the world are the supersonic Concorde and the Russian-built Tupolev Tu-144. The Concorde, which operated from 1976 to 2003, could travel at speeds of up to 1,350 miles per hour, twice the speed of sound. The Tu-144, which operated from 1968 to 1978, could travel at speeds of up to 1,200 miles per hour. However, both planes were retired due to high operating costs and safety concerns.

Currently, the fastest commercial planes in operation are the Boeing 787 Dreamliner and the Airbus A350. These planes can travel at speeds of up to 650 miles per hour and are known for their fuel efficiency and long-range capabilities.

Lufthansa Airbus A350-900 at Tokyo Haneda International Airport

How Commercial Plane Speeds Are Measured

Commercial plane speeds are measured in knots, a unit of speed equivalent to one nautical mile per hour. One nautical mile is equivalent to 1.15 miles on land. Planes typically travel at speeds of between 400 and 700 knots, depending on their type and the conditions they are flying in.

Air traffic control regulations may require planes to fly at specific speeds, which are communicated to the pilots through the plane’s instruments and radio communications.

The Impact of Weather on Commercial Plane Speeds

Weather conditions can significantly impact commercial plane speeds. Strong headwinds can slow down a plane’s speed, while tailwinds can push a plane forward, increasing its speed. Thunderstorms, snow, and ice can also affect a plane’s speed and safety.

Pilots are trained to navigate through adverse weather conditions, and planes are equipped with advanced weather radar and communication systems to help them avoid and navigate through dangerous weather conditions.

Safety Considerations Related to Commercial Plane Speeds

Safety is a top priority in the aviation industry, and commercial plane speeds are regulated to ensure the safety of passengers and crew. Air traffic control regulations may require planes to fly at specific speeds to maintain safe distances between planes and avoid collisions.

Planes also have speed limits during takeoff and landing to ensure safe and smooth operations.

The weight of the plane is also a safety consideration related to speed. Overloading a plane with too much weight can affect its speed and fuel efficiency, compromising its safety. Airlines are required to adhere to strict weight and balance limits to ensure the safety of their passengers and crew.

Advancements in Commercial Aviation Technology and Their Impact on Plane Speeds

Advancements in commercial aviation technology have paved the way for faster and more efficient planes. New materials, such as carbon fiber composites, have made planes lighter and more fuel-efficient, allowing them to travel faster and further.

Engine technology has also improved, with newer engines such as the Rolls-Royce Trent XWB and the General Electric GEnx offering greater fuel efficiency and thrust.

Rolls Royce Trent XWB engine powering the Airbus A350-900 XWB

In addition to improvements in materials and engine technology, advancements in avionics and communication systems have also impacted plane speeds. Advanced navigation systems and communication technologies allow planes to fly more direct routes, reducing flight times and improving fuel efficiency.

The Future of Commercial Plane Speeds

The future of commercial plane speeds is promising, with new technologies and innovations in development. Supersonic travel may make a comeback with companies such as Boom Supersonic and Aerion Supersonic developing supersonic planes that can travel at speeds of up to 1,500 miles per hour.

These planes could revolutionize air travel, making it possible to travel between destinations in a fraction of the time it takes today.

Advancements in electric and hybrid-electric propulsion systems also offer the potential for faster and more sustainable air travel. Companies such as Airbus and Rolls-Royce are developing electric and hybrid-electric planes that could reduce emissions and fuel consumption while increasing speed and efficiency.

Commercial plane speeds play a significant role in air travel, impacting travel times, fuel efficiency, and safety. The different types of commercial planes have unique speed capabilities, with narrow-body planes used for short to medium-haul flights, wide-body planes used for long-haul flights, and regional jets used for short-haul regional flights.

Factors that affect commercial plane speeds include weather conditions, air traffic control regulations, and the weight of the plane. The fastest commercial planes in the world are the Concorde and Tupolev Tu-144, while the Boeing 787 Dreamliner and Airbus A350 are currently the fastest commercial planes in operation.

The future of commercial plane speeds is promising, with advancements in technology offering potential for faster and more sustainable air travel.

Kudzi Chikohora is a B737 captain with over 3,000 hours of flying in Europe. He holds a Master’s degree in Aerospace Engineering, is a chartered engineer, and is a member of the Royal Aeronautical Society.

Kudzi completed his pilot training via the self-funded modular pilot training route and created kcthepilot.com to share pilot training and aviation content.

The need for speed: how fast can a plane really go, a guide to gcses for aspiring pilots: what you need to know, can passenger jets land themselves (the truth about autoland), can a plane fly if all engines have failed, similar posts.

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Quite an informative and helpful article about commercial planes and their speeds

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principles of flight

Principles of Flight

The Four Forces and Three Axes of Rotation

Introduction:

The principles of flight are the aerodynamics dealing with the motion of air and forces acting on an aircraft
Lift is the most apparent force, as it's what we think of as giving an aircraft the ability to fly
Thrust provides a method with which to move the aircraft
Understanding how these forces work together and knowing how to control them with the use of power and flight controls are essential to flight

Lift is the critical aerodynamic force that brings an aircraft to fly
Common airfoils include not just the wings but the flaps/slats and stabilizers too
This means "up" is relative to the aircraft, and being in a turn or even upside down changes the direction the lift vector points (a key principle in understanding turn performance and aerobatics )
Note that the center of lift is almost always behind the center of gravity, resulting in a nose-down attitude if not countered by the tail

In straight and level flight, to be effective, the total lift must overcome the total weight of the aircraft, comprised of the actual weight and the tail-down force used to control the aircraft's pitch attitude
This means that when performing a loop , for example, the lift vector is still perpendicular to the relative wind, which would have the lift vector pointing toward the ground as the aircraft becomes inverted

Bernoulli's Principle:

Bernoulli's principle demonstrates that as the velocity of a moving fluid (liquid or gas) increases, the pressure within the fluid decreases
A = Area, V = Velocity, and P = Pressure
Assuming the area is constant, you get: V 1 P 1 = V 2 P 2
The formula shows that as the velocity of the fluid (air) increases, its pressure must decrease
The rounded upper surface increases the velocity of the air, which causes pressure to decrease
As pressure above the wing decreases, the relative pressure below it is higher, creating a pressure differential, which we know as lift
Note: with regards to rotary-wing aircraft, lift and thrust are both in the vertical direction
Note: We say lift is created by air moving faster over the top of the wing, but more specifically, it's the decreased pressure which causes lift

Newton's Laws of Motion:

Newton's first law:.

This means that nothing starts or stops moving until some outside force causes it to do so
An aircraft at rest on the ramp remains at rest unless a force strong enough to overcome its inertia is applied
Once it is moving, its inertia keeps it moving, subject to the various other forces acting on it
These forces may add to its motion, slow it down, or change its direction

Newton's second law:

This takes into account the factors involved in overcoming Newton's First Law
It covers both changes in direction and speed, including starting up from rest (positive acceleration) and coming to a stop (negative acceleration or deceleration)
The equation F(force)=M(mass)A(acceleration) may express this law where the force is equal to the mass times the acceleration

Newton's Third Law:

In an airplane, the propeller moves and pushes back the air; consequently, the air pushes the propeller (and thus the airplane) in the opposite direction (forward)
This principle applies whenever two things act upon each other [ Figure 4 ]

Lift as an Equation:

The magnitude of the force of lift (L) is directly proportional to the Coefficient of Lift (CL) , the density of the air (ρ) , the area of the wings (S) , and the velocity (airspeed) (V) [ Figure 5 ]
The mean camber is important because it assists in determining aerodynamic qualities of an airfoil
The measurement of the maximum camber, inclusive of both the displacement of the mean camber line and its linear measurement from the end of the chord line, provides properties useful in evaluating airfoils

Coefficient of Lift:

The lift coefficient is a number that aerodynamicists use to model all of the complex dependencies of shape, inclination, and some flow conditions on lift

Air Density:

If air density decreases and the total lift must equal the total weight to remain in flight, it follows that another factor needs to increase
The factor usually increased is the airspeed or the Angle of Attack (AOA) because these are controlled directly by the pilot
The lift varies directly with the wing area, provided there is no change in the wing's planform
If the wings have the same proportion and airfoil sections, a wing with a planform area of 200 square feet lifts twice as much at the same AOA as a wing with an area of 100 square feet
The shape of the wing or rotor cannot be effective unless it continually keeps "attacking" new air
If an aircraft is to keep flying, the lift-producing airfoil must keep moving
In a helicopter or gyroplane, the rotation of the rotor blades creates the necessary lift
For other types of aircraft, such as airplanes, weight shift control, or gliders, air must be moving across the lifting surface by way of forward speed
The forward speed of the aircraft accomplishes this
Lift is proportional to the square of the aircraft's velocity, meaning that an airplane traveling at 200 knots has four times the lift as the same airplane traveling at 100 knots if the AOA and other factors remain constant
All other factors being constant, for every AOA, there is a corresponding airspeed required to maintain altitude in steady, unaccelerated flight (true only if maintaining level flight). Since an airfoil always stalls at the same AOA, the lift must increase if weight increases. The only method of increasing lift is by increasing velocity if the AOA is held constant just short of the "critical," or stalling, AOA (assuming no flaps or other high lift devices). Lift and drag also vary directly with the density of the air. Density is affected by several factors: pressure, temperature, and humidity. At an altitude of 18,000 feet, the air density is one-half the air density at sea level. An aircraft must fly at a greater true airspeed for any given AoA to maintain its lift at a higher air density altitude. Warm air is less dense than cool air, and moist air is less dense than dry air. Thus, on a hot, humid day, an aircraft must be flown at a greater true airspeed for any given AOA than on a cool, dry day

Controlling Lift:

Angle of Attack
Velocity/airspeed

Angle of Attack:

Airplane Flying Handbook,Coefficients of lift and drag at various angles of attack

AOA is fundamental to understanding many aspects of airplane performance, stability, and control
AoA is the acute angle measured between the relative wind or flight path and the chord of the airfoil [ Figure 2 ]
As the AOA increases, lift increases (all other factors being equal)
This is the stalling AOA, known as CL-MAX (maximum CL)critical AOA
The CL increases until reaching the critical AOA, then decreases rapidly with any further increase in the AOA [ Figure 6 ]
Lift created (or reduced in the case of negative AoA) is measured with the coefficient of lift , which relates to the AoA
Every airplane has an angle of attack where the maximum lift occurs ( stall )

Velocity/Airspeed:

For instance, in straight-and-level flight, cruising along at a constant altitude, altitude is maintained by adjusting lift to match the aircraft's velocity or cruise airspeed while maintaining a state of equilibrium in which lift equals weight
In an approach to landing, when the pilot wishes to land as slowly as practical, it is necessary to increase AOA near maximum to maintain lift equal to the weight of the aircraft
An aircraft could not continue to travel in level flight at a constant altitude and maintain the same AOA if the velocity increases. The lift would increase, and the aircraft would climb due to the increased lift force or speed up. Therefore, to keep the aircraft straight and level (not accelerating upward) and in equilibrium, lift must be kept constant as velocity increases. This is normally accomplished by reducing the AOA by lowering the nose. Conversely, as the aircraft is slowed, the decreasing velocity requires increasing the AOA to maintain lift sufficient to maintain flight. There is a limit to how far the AOA can be increased if a stall is to be avoided

Lift/Drag Ratio:

The lift-to-drag ratio (L/D) is the amount of lift generated by a wing or airfoil compared to its drag
A L/D ratio is an indication of airfoil efficiency
Aircraft with higher L/D ratios are more efficient than those with lower L/D ratios
In unaccelerated flight with the lift and drag data steady, the proportions of the coefficient of lift (CL) and coefficient of drag (CD) can be calculated for specific AOA [ Figure 7 ]
The coefficient of lift is dimensionless and relates the lift generated by a lifting body, the dynamic pressure of the fluid flow around the body, and a reference area associated with the body
The coefficient of drag is dimensionless, used to quantify the drag of an object in a fluid environment, such as air, and is always associated with a particular surface area
This is the same as dividing the lift equation by the drag equation, as all of the variables, aside from the coefficients, cancel out
At high AOA, small changes in the AOA cause significant changes in drag
The shape of an airfoil and changes in the AOA affect the production of lift
Notice in [ Figure 6 ] that the coefficient of lift curve (red) reaches its maximum for this particular wing section at 20° AOA and then rapidly decreases
20° AOA is, therefore, the critical angle of attack
The coefficient of drag curve (orange) increases very rapidly from 14° AOA and completely overcomes the lift curve at 21° AOA
The lift/drag ratio (green) reaches its maximum at 6° AOA, meaning that at this angle, the most lift is obtained for the least amount of drag
Note that the maximum lift/drag ratio (L/D MAX ) occurs at one specific CL and AOA
If the aircraft operates in steady flight at L/D MAX , the total drag is at a minimum
Any AOA lower or higher than that for L/D MAX reduces the L/D and consequently increases the total drag for a given aircraft's lift
[ Figure 7 ] depicts the L/D MAX by the lowest portion of the blue line labeled "total drag
The configuration of an aircraft has a great effect on the L/D

Pilot Handbook of Aeronautical Knowledge, Typical Airfoil Section

Airfoil Design:

Airfoil construction takes advantage of the air's response to Newton's and Bernoulli's principles
Air acts in various ways when submitted to different pressures and velocities: a positive pressure lifting action from the air mass below the wing and a negative pressure lifting action from lowered pressure above the wing
However, the balance of the lift needed to support the aircraft comes from the flow of air above the wing
Herein lies the key to flight
It is neither accurate nor useful to assign specific values to the percentage of lift generated by an airfoil's upper surface versus that generated by the lower surface
These are not constant values. They vary, not only with flight conditions but also with different wing designs
No one airfoil can satisfy every flight requirement
The weight, speed, and purpose of each aircraft dictate the shape of its airfoil
The most efficient airfoil for producing the greatest lift is one that has a concave or "scooped out" lower surface
As a fixed design, this airfoil type sacrifices too much speed while producing lift and is not suitable for high-speed flight
Advancements in engineering have made it possible for today's high-speed jets to take advantage of the concave airfoil's high lift characteristics
Leading-edge (Kreuger) flaps and trailing-edge (Fowler) flaps, when extended from the basic wing structure, literally change the airfoil shape into the classic concave form, thereby generating much greater lift during slow flight conditions
[ Figure 8 ] shows some of the more common airfoil designs

Airfoil Construction:

By looking at the cross-section of a wing, one can see several prominent characteristics of design [ Figure 8/9 ]
The camber of the upper surface is more pronounced than that of the lower surface, which is usually somewhat flat
The two extremities of the airfoil profile also differ in appearance as the rounded end, which faces forward in flight, is called the leading edge; the other end, the trailing edge, is relatively narrow and tapered

Chord Line:

A straight line connecting the extremities of the leading and trailing edges denotes the Chord Line
The Chord line is a reference line often used in discussing the airfoil
The distance from this chord line to the upper and lower surfaces of the wing denotes the upper and lower magnitude of camber at any point
Another reference line, drawn from the leading edge to the trailing edge, is the mean camber line
This mean line is equidistant at all points from the upper and lower surfaces

High Pressure Below:

Because of air flows underneath the airfoil, a positive pressure results, particularly at higher angles of attack
At a point close to the leading edge, the airflow nearly stops (stagnation point) and then gradually increases in speed
At some point near the trailing edge, it again reaches a velocity equal to that on the upper surface
In conformance with Bernoulli's principle, positive upward pressure is created where the airflow slowed beneath the airflow (i.e., the fluid speed decreases, the pressure must increase)
Since the pressure differential between the upper and lower surface of the airfoil increases, total lift increases

Low Pressure Above:

If the airfoil were then inclined so the airflow strikes it at an angle, the air moving over the upper surface would be forced to move faster than the air moving along the bottom of the airfoil
This increased velocity reduces the pressure above the airfoil
Applying Bernoulli's Principle of Pressure, the increase in airspeed across the top of an airfoil produces a pressure drop. This lowered pressure is a component of total lift. The pressure difference between the upper and lower surface of a wing alone does not account for the total lift force produced
This downwash meets the flow from the bottom of the airfoil at the trailing edge
Applying Newton's third law, the reaction of this downward backward flow results in an upward forward force on the airfoil

Pressure Distribution:

As air flows along the surface of a wing at different AOAs, there are regions along the surface where the pressure is negative or less than atmospheric and regions where the pressure is positive or greater than atmospheric
This negative pressure on the upper surface creates a relatively larger force on the wing than is caused by the positive pressure resulting from the air striking the lower wing surface [ Figure 10 ]
The average pressure variation for any given AOA is called the center of pressure (CP). The aerodynamic force acts through this CP. At high angles of attack, the CP moves forward, while at low angles of attack, the CP moves aft. In the design of wing structures, this CP travel is essential since it affects the position of the air loads imposed on the wing structure in low and high AOA conditions. Changes in the CP govern an airplane's aerodynamic balance and controllability

Pilot Handbook of Aeronautical Knowledge, Airfoil Designs

Airfoil Behavior:

The lift production is much more complex than a simple differential pressure between upper and lower airfoil surfaces. Many lifting airfoils do not have an upper surface longer than the bottom, as in symmetrical airfoils. These are seen in high-speed aircraft with symmetrical wings or symmetrical rotor blades for many helicopters whose upper and lower surfaces are identical. In both examples, the only difference is the airfoil relationship with the oncoming airstream (angle). A paper airplane, which is simply a flat plate, has a bottom and top shape and length. Yet, these airfoils do produce lift, and "flow turning" is partly (or fully) responsible for creating lift
As an airfoil moves through the air, the airfoil is inclined against the airflow, producing a different flow caused by the airfoil's relationship to the oncoming air. Think of a hand placed outside the car window at high speed. If the hand inclines in one direction or another, the hand will move upward or downward. Deflection causes the air to turn about the object within the air stream. The velocity about the object changes in both magnitude and direction, in turn resulting in a measurable velocity force and direction

Wingtip Vortices & Lift:

Pilot Handbook of Aeronautical Knowledge, Tip Vortex

While the biggest consideration for producing lift involves the air flowing over and under the wing, there is a third dimension to consider
Consider the tip of the airfoil also has an aerodynamic effect
To equalize pressure, the high-pressure area on the bottom of an airfoil pushes around the tip to the low-pressure area on the top [ Figure 11 ]
This action creates a rotating flow called a tip vortex or wingtip vortices
This downwash extends back to the trailing edge of the airfoil, reducing lift for the affected portion of the airfoil
Manufacturers have developed different methods to counteract this action
Winglets can be added to the tip of an airfoil to reduce this flow (essentially decrease induced drag)
The winglets act as a dam preventing the vortex from forming
Winglets can be on the top or bottom of the airfoil
Another method of countering the flow is to taper the airfoil tip, reducing the pressure differential and smoothing the airflow around the tip
High-Lift Devices
Lift is proportional to the square of the speed (Lift = V 2 )
It is the combined load of the aircraft itself, the crew, the fuel, and the cargo or baggage
A Load is essentially the back pressure on the control stick required, the G-loading , which an aircraft experiences
Passengers and fuel are more obvious
Opposing lift, as an aircraft is descending
Weight has a definite relationship to lift
This relationship is simple but important in understanding the aerodynamics of flying
Lift is the upward force on the wing acting perpendicular to the relative wind and perpendicular to the aircraft's lateral axis
Lift is required to counteract the aircraft's weight
In stabilized level flight, when the lift force is equal to the weight force, the aircraft is in a state of equilibrium and neither accelerates upward, or downward
If lift becomes less than weight, the vertical speed will decrease
When the lift is greater than the weight, the vertical speed will increase
It is through excesses or deficits of thrust that accelerations and decelerations can occur
The aircraft will continue to speed up/slow down until thrust again equals drag, at which point the airspeed will stabilize
In powered aircraft, thrust is achieved through the powerplant, be it a propeller, rotor, or turbine
With a glider, thrust is created through the conversion of potential energy (altitude) to kinetic energy (airspeed) by pitching toward the ground
This law may be expressed by F = MA (Force equals Mass times Acceleration), for example, speeding up, slowing down, entering climbs or descents, and turning
Acts parallel to the center of thrust to overcome drag, F = MA
As a general rule, thrust acts parallel to the longitudinal axis

Measuring Thrust:

Propeller & rotor driven aircraft are generally rated in horsepower
Turbine-driven aircraft are generally rated in pounds

Thrust During Acceleration:

Increasing engine power increases thrust (now exceeding drag), thereby accelerating the aircraft
As long as the thrust continues to be greater than the drag, the aircraft continues to accelerate
When drag equals thrust, the aircraft flies at a constant airspeed

Thrust during Deceleration:

When reducing engine power, lessoning thrust, thereby decelerating the aircraft
As long as the thrust is less than the drag, the aircraft continues to decelerate
To a point, as the aircraft slows down, the drag force will also decrease
The aircraft will continue to slow down until thrust again equals drag, at which point the airspeed will stabilize

Straight-and-level flight:

Pilot Handbook of Aeronautical Knowledge, ngle of Attack at Various Speeds

The pilot coordinates AOA and thrust in all speed regimes if the aircraft is to be held in level flight
Remember, (for a given airfoil shape) lift varies with the AOA and airspeed
Therefore, a large AOA at low airspeeds produces an equal amount of lift at high airspeeds with a low AOA

Low-Speed Flight:

When the airspeed is low, the AOA must be relatively high if the balance between lift and weight is to be maintained [ Figure 12 ]
If thrust decreases and airspeed decreases, the lift will become less than weight, and the aircraft will start to descend
To maintain level flight, the pilot can increase the AOA by an amount that generates a lift force again equal to the weight of the aircraft
While the aircraft will be flying more slowly, it will still maintain level flight

Cruising Flight

Straight-and-level flight in the slow-speed regime provides some interesting conditions relative to the equilibrium of forces
With the aircraft in a nose-high attitude, there is a vertical component of thrust that helps support it
For one thing, wing loading tends to be less than would be expected
In level flight, when thrust increases, the aircraft speeds up, and the lift increases
The aircraft will start to climb unless the AOA is decreased just enough to maintain the relationship between lift and weight
The timing of this decrease in AOA needs to be coordinated with the increase in thrust and airspeed. Otherwise, if the AOA decreases too fast, the aircraft will descend, and if the AOA decreases too slowly, the aircraft will climb

High-Speed Flight

As the airspeed varies due to thrust, the AOA must also vary to maintain level flight
At very high speeds and level flight, it is even possible to have a slightly negative AOA
As thrust reduces and airspeed decreases, the AOA must increase to maintain altitude
If speed decreases enough, the required AOA will increase to the critical AOA
Any further increase in the AOA will result in the wing stalling
Therefore, extra vigilance is required at reduced thrust settings and low speeds so as not to exceed the critical angle of attack
If equipped with an AOA indicator, it should be referenced to help monitor the proximity to the critical AOA
Aircraft like the V-22 and F-35, pivot the engines or vector the exhaust to change the direction of the thrust rather than changing the AOA

Drag is the rearward, resisting force caused by disruption of airflow
Drag is the net aerodynamic force parallel to the relative wind
Drag is always a by-product of lift and thrust
Always a by-product of lift
There are two basic types of drag (induced and parasite), with total drag being a combination of the two [ Figure 13 ]

Induced Drag:

In level flight, the aerodynamic properties of a wing or rotor produce a required lift, but this can be obtained only at the expense of a certain penalty
That penalty, induced drag, is inherent whenever an airfoil is producing lift
Causes wingtip vortices
Decreases with airspeed
Induced drag = 1/V
To state this another way, the lower the airspeed, the greater the AOA required to produce lift equal to the aircraft's weight and, therefore, the greater induced drag. The amount of induced drag varies inversely with the square of the airspeed

Wingtip Vortices & Drag:

Pilot Handbook of Aeronautical Knowledge, Wingtip Vortex From Crop Duster

An airfoil (wing or rotor blade) produces the lift force by using the energy of the free airstream. Whenever an airfoil produces lift, the pressure on the lower surface is greater than on the upper surface (Bernoulli's Principle). As a result, the air tends to flow from the high-pressure area below the tip upward to the upper surface's low-pressure area. There is a tendency for these pressures to equalize in the vicinity of the tips, resulting in a lateral flow outward from the underside to the upper surface. This lateral flow imparts a rotational velocity to the air at the tips, creating vortices that trail behind the airfoil
When the aircraft is viewed from the tail, these vortices circulate counterclockwise about the right tip and clockwise about the left tip. [ Figure 14 ] As the air (and vortices) roll off the back of your wing, they angle down, known as downwash. [ Figure 15 ] shows the difference in downwash at altitude versus near the ground. Bearing in mind the direction of rotation of these vortices, it can be seen that they induce an upward flow of air beyond the tip and a downwash flow behind the wing's trailing edge. This induced downwash has nothing in common with the downwash necessary to produce lift. It is, in fact, the source of induced drag. Downwash points the relative wind downward, so the more downwash you have, the more your relative wind points downward. That's important for one very good reason: lift is always perpendicular to the relative wind. In [ Figure 16 ], you can see that your lift vector is more vertical, opposing gravity when you have less downwash. And when you have more downwash, your lift vector points back more, causing induced drag. On top of that, it takes energy for your wings to create downwash and vortices, and that energy creates drag
The greater the size and strength of the vortices and the consequent downwash component on the airfoil's net airflow, the greater the induced drag effect becomes. This downwash over the top of the airfoil at the tip has the same effect as bending the lift vector rearward; therefore, the lift is slightly aft of perpendicular to the relative wind, creating a rearward lift component. This is induced drag

Parasite Drag:

As the term parasite implies, it is the drag that is not associated with the production of lift
Parasite drag includes the displacement of the air by the aircraft, turbulence generated in the airstream, or a hindrance of air moving over the surface of the aircraft and airfoil

Profile/Form Drag:

Form drag is the portion of parasite drag generated by the aircraft and components (antennas, wheels, etc.) due to its shape and airflow around it
Turbulent wake caused by the separation of airflow (burbling) created by the shape of the aircraft [ Figure 17 ]
When the air has to separate to move around a moving aircraft and its components, it eventually rejoins after passing the body
Newer aircraft are generally made with consideration to this by fairings along the fuselage so that turbulence and form drag is reduced [ Figure 18 ]

Interference Drag:

Generated by the collision of air-streams creating eddy currents, turbulence, or restrictions to the smooth flow
For example, landing gear meeting the fuselage
The most interference drag is created when two surfaces meet at perpendicular angles
If a jet fighter carries two identical wing tanks, the overall drag is greater than the sum of the individual tanks because both of these generate interference drag
Fairings and distance between lifting surfaces and external components (such as radar antennas hung from wings) reduce interference drag. [Figure 5-8]
Learn more about the effects of interference drag here

Skin Friction Drag:

Every surface, no matter how apparently smooth, has a rough, ragged surface when viewed under a microscope
The air molecules, which come in direct contact with the surface of the wing, are virtually motionless
Each layer of molecules above the surface moves slightly faster until the molecules are moving at the velocity of the air mass moving around the aircraft
This speed is called the free-stream velocity
The area between the wing and the free-stream velocity level is about as wide as a playing card and is called the boundary layer
At the top of the boundary layer, the molecules increase velocity and move at the same speed as the molecules outside the boundary layer
The actual speed at which the molecules move depends upon the shape of the wing, the viscosity (stickiness) of the air, and its compressibility (how much it can be compacted)
The boundary layer gives any object an "effective" shape that is usually slightly different from the physical shape
The boundary layer may also separate from the body, thus creating an effective shape much different from the physical shape of the object
This change in the physical shape of the boundary layer causes a dramatic decrease in lift and an increase in drag
When this happens, the airfoil has stalled
Also, a smooth and glossy finish aids in the transition of air across the surface of the wing
Since dirt on an aircraft disrupts the free flow of air and increases drag, keep the surfaces of an aircraft clean and waxed
Drag can be caused intentionally through the use of speed brakes, spoilers, or dive brakes
Additionally, normal procedures such as lowering flaps can increase drag
Thus, as airspeed decreases to near the stalling speed in a steady state, the total drag becomes greater due mainly to the exponential rise in induced drag. Similarly, as the aircraft reaches its never-exceed speed (V NE ), the total drag increases rapidly due to the sharp increase of parasite drag

Interaction Between the Four Forces of Flight:

The four forces of flight do not exist in isolation as each influences the other
Lift opposing weight, and drag opposing thrust is only true in level flight
For example, a pitch-up requires thrust to not only overcome drag but also weight

Ground Effect:

Reduction of induced drag during takeoffs and landings
Caused by a reduction of wingtip vortices
It occurs at about a wingspan above the ground
Up-wash and down-wash decrease
Down-wash can hit the ground and push the wing from below, forming what feels like a cushion
Causes floating if fast on approach
More noticeable in a low-wing aircraft
Increases lift while decreasing drag (induced)
The opposite is true when leaving ground effect

Critical Definitions:

Rotor Blade: spinning "wings" which allow for lift on helicopters or "rotor-craft"
Stabilizer: a control surface other than the wings that provide stabilizing qualities
Chord: Chord line longitudinal length (length as viewed from the side)
Chord Line: The chord line is the straight line intersecting the leading and trailing edges of the airfoil
Angle of Incidence (AoI): the angle formed by the airfoil chord and the longitudinal axis of the aircraft, which is designed into the aircraft and cannot be changed by the pilot
Attitude: relationship of the aircraft's nose with the horizon
Flight Path: The course or track along which the aircraft is flying or is intended to be flown
Lift: A component of the total aerodynamic force on an airfoil that acts perpendicular to the relative wind
Center of Gravity: The average weight across an aircraft through which gravity is considered to act
Weight: Opposes lift via gravity
Thrust: Forward force that propels the airplane
Drag: Retarding force which limits speed

Principles of Flight Airman Certification Standards:

Aircraft stresses:.

During flight, landings, and takeoffs numerous forces or stresses are exerted on an aircraft which all contribute to fatigue
Fatigue, or fatigue life, is a limiting factor when considering the useful life, or service life, of an aircraft
Tension: The resistance to pulling apart or stretching produced by two forces pulling in opposite directions along the same straight line
Compression: The opposite of tension, the resistance to crushing produced by two forces pushing toward each other in the same straight line
Bending: A combination of tension and compression caused by simple bending of an object (inside area is compressed and the outside area is stretched
Torsion: A twisting force or motion most common in engine torque or rotation
Shearing: Stress exerted when two pieces of material which are fastened together tend to be separated by sliding one over the other, each piece in and the opposite direction

Conclusion:

Although simplified as thrust, lift, weight, and drag, we know that there are more upward forces than lift, and there are more downward forces than just weight
Although the pilot can only have limited control of some of these factors, principally, lift is affected by wing design, angle of attack, velocity, weight and loading, air temperature, and humidity
Both Bernoulli's Principle and Newton's Laws are in operation whenever an airfoil generates lift
To achieve flight, we must overcome drag and resist gravity
To maintain a constant airspeed, thrust, and drag must remain equal, just as lift and weight must be equal to maintain a constant altitude
Although AoA and velocity allow a pilot to manipulate lift, other factors are slightly under pilot control, such as air density (as a pilot could change altitude)
A balanced aircraft is a happy aircraft (fuel burn, efficiency, etc.)
Several books are available in digital and hard copy to help you learn more [Amazon]
Equilibrium is defined as lift equaling down-force (weight+tail downforce [which makes up ~5% of aircraft weight]) and thrust equaling drag, but by changing these forces, we can affect climbs, descents, and other maneuvers
To learn more, consider AOPA's Essential Aerodynamics online course
Check out the FAA's Angle of Attack fact sheet for more information about AoA
CFI Notebook.net - Wake Turbulence
CFI Notebook.net - Weight and Balance
CFI Notebook.net - Aircraft Stability
CFI Notebook.net - Airplane Stall and Recovery Procedures
Still looking for something? Continue searching:

References:

Aircraft Owners and Pilots Association - Aerodynamics
Aircraft Owners and Pilots - Aerodynamics Resources
Aircraft Owners and Pilots Association - Aircraft Maintenance: Tips for Prop Tracking
Airplane Flying Handbook
Federal Aviation Administration - Instrument Flying Handbook (2-2) Review of Basic Aerodynamics
Federal Aviation Administration - Pilot/Controller Glossary
Federal Aviation Administration - Safety Team: Angle of Attack Awareness

Why is Airspeed Measured In Knots? : Why Airplanes Use Knots!

Hundreds of years ago, our ancestors started exploration through sea voyages. They quickly learned that navigation in the sea presented unique challenges as it was quite easy to get lost within the vastness of the oceans. Traditional techniques and units of measure failed at sea as there were no landmarks to identify, and no way of knowing the distance traveled. That was when “nautical miles” were defined as a unit of distance at sea and it is the same unit of measure which was later adopted in aviation.

With that said, with the advent of modern navigation and positioning systems, we are now able to navigate easily through air, sea, or land and can alternate between any units of measurement we like. So, why is the speed of aircraft still measured in knots?

Airplanes use ‘knots’ not only because it makes air navigation easier, but also because it is recommended as a unit of airspeed measurement by the International Civil Aviation Organization (ICAO) .

This unit for airspeed in uniformly accepted around the globe as ICAO recommends all aircraft manufacturers to use knots for the airspeed indicators. Owing to its traditional value and global acceptability, the unit ‘knots’ has made a permanent space for itself in the aviation sector.

With that said, let’s learn more about knots, why they are still used, and how they came about in the first place!

Table of Contents

How much is one knot (1 kt)? : Nautical miles vs knots

Historically, one nautical mile was defined as the distance equal to one minute of latitude.

To put this in perspective, if the earth is vertically sliced into 360 equidistant degrees, each degree would contain 60 minutes. It was approximated that one-sixtieth (1/60) distance between two latitudes had been traveled in one nautical mile.

A knot, in turn, is a unit of speed measurement, defined as one nautical mile per hour.

Here is a video that might be of use to you if you struggle to grasp this concept!

Historical Vs modern knot distances

In the good old times, one knot (1kt) was a slight approximation, as one nautical mile did not represent a standard fixed distance.

This was because the distance between latitudes varies on the equator (1843 meters) as compared to that on the poles (1861 meters), so the value of the nautical mile used to be different as well.

Due to a lack of precise navigational aids, nautical miles and knots remained the best approximation for distance speed for hundreds of years.

This approximation of knots has now been replaced by a precise value and we will read about that; but first, let us see how the term ‘knots’ came about!

The Modern Definition of one knot

The precise value of one knot (1kt) in terms of SI units is 1.852km/h .

With the advent of GPS and precise navigational aids, the need to precisely define and standardize the value of 1 knot (kt) arose.

In 1906, France became the first country to define one nautical mile (1Nm) as equal to exactly 1852m which was later adopted by the rest of the world.

Knots Vs Other Standard Units of Speed

With the precise definition of knots, we are now able to accurately compare one knot (1kt) against other units of speed:

1kt = 1.852km/h = 0.514m/s = 1.1508miles/h = 1.688feet/s

Why are knots called “knots”?

You may be wondering why a speed of one nautical mile per hour is termed as ‘knots’? After all, it’s a quite strange name.

To understand this better, we need to take a history trip to see how sailors measured the speed of ships centuries ago.

To estimate the speed of a ship during long voyages, sailors used a “dutchman’s log”. A dutchman’s log was a wooden device having fixed weight and dimensions, attached to a rope with knots on it.

This log was thrown into the sea by sailors while letting the knotted rope slide through their hands for 30 seconds. The number of knots which would pass through a sailor’s hand during 30 seconds gave an approximation of the speed of the vessel in, you guessed it, ‘knots’.

While techniques for speed measurement of ships evolved with time, the unit of measure ‘knots’ was retained.

But why do we still use knots when it comes to aviation?

Why are Knots still used in aviation?

Most countries of the world have adopted the International System of Units (SI) where speed is measured in meters per second (m/s) or kilometers per hour (km/h) but the ICAO recommendation for utilization of that knots (kt) has not been altered.

The standards and recommendations given by ICAO are based on their acceptability across the globe and followed internationally by everyone connected to air navigation, including pilots and air traffic controllers.

Advantages of using Knots

The key advantage of using ‘knots’ as we have discussed above, is to simplify navigation in air.

In aviation, the air routes are defined in terms of waypoints (latitude, longitude) and their distance is expressed in terms of nautical miles, hence, the utilization of knots provides a quick estimation of time and speed requirements for aviators.

Additionally, aviators feel comfortable using ‘knots’ as this unit of measure as it ranges within nominal values of 0kt -400kt for commercial airliners. Whereas, in comparison, the value of the SI unit, kilometers per hour (km/h) would be quite much larger.

Airspeed represented in terms of knots also indicates that it is fundamentally different from the Ground Speed. As the airspeed of an aircraft is calculated directly from the pressure of the airflow hitting the aircraft, it may be significantly different from the speed it actually moves over the ground. Hence, using ‘knots’ for airspeed helps maintain the distinction between airspeed and ground speed.

Disadvantages of using Knots

The SI units of measurement like km/h, have established themselves within land-based transportation systems and vehicles. So, whenever a comparison in the speed of aircraft versus ground vehicles is needed, we are presented with a challenge.

Owing to its advantages, the airspeed of aircraft is always represented in ‘knots’. But it is important to note that there are three distinct types of airspeeds:

Knots Indicated Airspeed (KIAS)
Knots Calibrated Airspeed (KCAS)
Knots True Airspeed (KTAS).

Did you notice that “knots’ is common in all of them?

Let’s have a closer look it!

What are KIAS, KCAS and KTAS?

Well, as we discussed above, the airspeed of aircraft is always indicated and described in ‘knots’.

But for a quick review, let us summarize the three types of airspeeds for you:

Knots Indicated Airspeed: This is the airspeed (in knots) directly calculated from the air pressure inside the pitot probe of aircraft and it represents the speed of airflow as the aircraft travels through the air
Knots Calibrated Airspeed: By correcting for the minor instrumental and positional errors of the pitot probe we get the Knots Calibrated Airspeed.
Knots True Airspeed: True airspeed is the speed of the aircraft, relative to the stationary air around it. The values of indicated and true airspeed diverge as we move to higher altitudes owing to a difference in static air pressure.

If you want to learn more about the differences between these three types of airspeed, we recommend looking closer at our article about KIAS, KCAS, and KTAS .

Let us now summarize what we have discussed above.

The units, Nautical Mile for distance and Knots for speed, were derived by sailors in the 17th century. These units of measurement are directly related to the distance between two latitude lines and therefore, they made navigation in the sea a lot easier.
As the aviation sector developed and progressed in the 20th century, it borrowed a lot of existing terminologies and units of measure from the marine sector. The unit of speed ‘knots’ has been the standard unit of speed in aviation since its beginning.
One knot (1kt) is equal to one nautical mile per hour (1Nm/h) and it has been defined to be equal to 1.852km/h in terms of SI units. The utilization of ‘knots’ has been recommended by ICAO and is therefore accepted and understood in aviation around the globe.
Although there are three distinct types of airspeeds, they are all measured in ‘knots’. Due to the ease in usage, understandability, and its history, ‘knots’ are expected to stay as a standard measurement of the speed of aircraft in the foreseeable future.
So, the next time, we hear the speed of aircraft being expressed in terms of ‘knots’, we will precisely know why.

Happy Flying!

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Jet Speeds Uncovered: How Fast Do Commercial Airplanes Fly?

Samantha Black

In this article we’ll answer the common question, how fast do planes fly.

There are a lot of factors that go into how fast commercial aircraft fly. In this article we’ll go over all of these factors but before we do, here’s the flight speeds of many common commercial aircraft.

Cruising Speeds for Common Commercial Airplanes

Here is how fast common commercial planes go.

I’ve listed them in the following order; Aircraft Type, Cruise Mach, Knots, MPH.

What Impacts the Speed of a Plane?

Airplane speed is a confusing subject because airplanes operate in the atmosphere, which is itself moving around.

When driving down the road in your car, your speed is a simple matter of miles per hour (or kilometers per hour, outside the US). But pilots and aircraft designers think about a lot more.

Fundamentally, the speed that matters to airline route planners and passengers is the speed the plane flies across the ground from Point A to Point B.

This is known as the ground speed.

This is exactly like driving your car, and the math is easy. If you go 60 mph for three hours, you’ll go 180 miles toward your destination. Ground speed is the airspeed of a plane with tailwinds added or headwinds subtracted.

Inside the cockpit, however, the pilot and plane are worried about how much air moves over the wings.

This measurement is called airspeed, and there are a few different types. True airspeed vs indicated airspeed.

True Airspeed (TAS) is the most accurate because it accounts for the air temperature and density, which changes with weather and altitude. Aircraft have airspeed gauges, but they often show Indicated Airspeed (IAS), which is less accurate and needs to be corrected.

How Is a Plane’s Speed Measured?

Aviators use nautical miles for measuring distance, which are different than the statute miles used in the US highway system. 1 NM is approximately 1.15 SM and one nautical mile per hour is called a “knot.” Therefore, aircraft speeds are typically reported in knots, not mph.

Jets have limitations on their design—they can’t fly too slow, but they also can’t fly too fast. Typical commercial airplanes are not designed to fly faster than the speed of sound, also known as Mach 1.

If they get too fast, the air begins forming shockwaves along the wing that can cause the aircraft to become uncontrollable. The speed they cannot exceed is called the Maximum Mach Number, or the Mmo.

How fast you’re flying in terms of Mach numbers requires some math, so a machmeter is included in planes where this is an issue. A machmeter means the pilot can see that they are not exceeding the Mmo without thinking about all the math. As a result, when a commercial airplane is flying at altitude, it is flying at a safe designed Mach number.

You might see the speeds of aircraft counted in either knots or Mach.

Different Speeds During Flight

It’s important to realize that aircraft don’t always fly at the same speed. For one thing, there’s a speed limit in the sky. All aircraft below 10,000 feet must slow down to 250 knots or less. Near busy airports, they must slow to 200 knots or less.

But beyond that, all aircraft have flight profiles that are followed on every flight. The pilots set the most efficient climbing, cruising, and descent settings.

Climb Speeds

Getting to a safe altitude as quickly as possible is always a priority because more altitude means more choices should there be an emergency or a loss of power.

This means getting off the runway with the best rate of climb, which will give you a lot of altitude quickly but at a slower forward speed.

However, the pilot will transition to a more efficient climb profile once the plane is at a safe altitude.

This means lowering the nose, reducing the engine power, and getting more forward speed at the expense of a slower climb rate.

Cruise Speed

The flight’s cruise phase is also done using a pre-arranged profile.

The pilot will set a desired engine power (and fuel burn) for the given flight, and the resulting airspeed or Mach number will determine their ground speed and range.

When looking at the cruise speed numbers above, you’ll notice that most airliners are remarkably similar in performance.

A Maximum Mach number of 0.9–0.95 is about all that is possible in a sub-sonic transport aircraft. This is because air is accelerated as it flows over some parts of the aircraft. So even though the plane’s speed is less than Mach 1, some airflow over parts of the plane is much closer to the speed of sound.

Without making the entire aircraft capable of supersonic flight, these planes are limited to somewhere around this speed.

What’s more, the air is far less dense at altitude than it is near the surface. Jet engines operate very efficiently there, but the aircraft’s wing does not.

It must fly very fast to have enough air flowing over it to avoid stalling.

For this reason, many airliners operate in a small window between fast enough to not stall and slow enough not to exceed the Mmo. The result is that many airliners today are flying around at roughly the same speeds.

At cruise speeds aircraft will sometimes have to change their speeds when flying through turbulence .

Descent Speeds

So, how fast do commercial aircraft fly during the descent?

Commercial planes make two types of descent: a cruise descent and a landing approach. Cruise descent means losing altitude without building up too much forward speed and exceeding their Mmo.

There is little change in their forward speed since they just reduce engine thrust and let gravity do the rest.

Descending through 10,000 feet means abiding by the 250-knot speed limit.

This requires less power and perhaps drag devices like air spoilers to slow the aircraft down. Since less air flows over the wings as it slows down, the pilot will use flaps to increase the lift the wings can make.

Approaching the airport means slowing down as much as possible while maintaining control of the aircraft. Most planes are shooting approaches at 150 knots or less.

This requires using wing flaps and other high-lift devices to maintain control.

Supersonic Air Travel

So how fast do commercial planes fly if they’re going at supersonic speeds?

“I wanna go fast.” -Ricky Bobby

No discussion of commercial airplane speeds would be complete without mentioning the Concorde.

The world’s only supersonic airliner flew in regular service from 1976 to 2003 for Air France and British Airways. The plane provides insight into why many modern commercial airplanes look and perform as they do today.

The Concorde set several records and logged more supersonic hours than any other aircraft before or since.

In 1996 a British Airways “Speedbird” flew from New York to London in 2 hours, 52 minutes thanks to a 175 mph tailwind. In 1992 and 1995, the same Air France Concorde set records circumnavigating the globe (east and westbound, albeit with many fuel stops each way). The quickest was the 1995 eastbound trip which was done in 31 hours, 27 minutes.

Only 20 Concordes were ever built, and while flying on the special plane was a sign of status, supersonic air travel never really took off.

For one thing, the plane was a gas guzzler and very expensive to operate. For another, the sonic booms it produced meant that it could only ever fly at those airspeeds over the open ocean. That made its feasibility for legs like New York to Los Angeles virtually nill.

New technologies may be changing the math, however. Several startups have begun designing new SSTs (supersonic transports, as the Concorde was called).

These new designs, built with modern techniques and computer-aided design, aim to reduce the sonic boom impact and improve fuel economy. Boom Supersonic has been making headlines with its planned Overture airliner and has secured orders from United and American Airlines.

While it hasn’t flown yet, the projected cruise speed of the Overture is Mach 1.75, making a flight from London to New York in about 3 hours, 30 minutes.

What Is a Commercial Plane?

When most people think of a commercial plane, they envision the airliner they’re booking tickets on. Commercial aviation has a lot of components, and airlines are the most visible part.

The most common type of airliner used today is a twin-engine turbofan.

Boeing and Airbus are major manufacturers, although Embraer and several other makers are now making smaller models. These planes are designed and built based on the airlines’ need to carry so many people so many miles at a time as efficiently as possible.

So, different models are made for short, medium, and long-haul flights.

And, of course, planes range from small models with 50 seats (or even less in some cases) to large “heavies” that can carry 500 or more.

When an airline decides which planes to buy and which routes to fly it on, it always comes down to dollars and cents.

Flying a large-capacity, long-haul plane nearly empty on short legs means not covering the flight’s cost and losing money. So airlines must constantly analyze the planes they have and want based on how they operate them.

More to the point, the speed at which a plane operates is a factor of its efficiency.

Ideally, the quicker one flight is done, then another can begin—with a new batch of paying customers. But getting there fast isn’t the only factor because flying faster uses more fuel.

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How Fast Do Planes Land? (By Aircraft Type)

The speed at which a plane lands mainly depends on the type of aircraft, and environmental factors, like wind speed.

The length of the runway, altitude, ground effects, air pressure, air temperature, air traffic control, visibility, and generally just the overall situation can all affect landings, though not all will necessarily affect how fast or slow a plane lands.

Table of Contents

1 Landing Speed By Aircraft Type
2 How Fast Planes Descend When Landing
3 Why It Sometimes Feels Like the Plane is Speeding Up Before Landing
4 Landing is More Dangerous than Taking Off

Landing Speed By Aircraft Type

Small Single Engine: A small single-engine plane lands at an average speed of approximately 100 knots (115 mph)
Small Multi-Engine: A small multiple engine plane lands at an average speed of approximately 120 knots (138 mph)
Commercial Airliner: A commercial airliner, like a Boeing 747 , lands at an average speed of approximately 150 knots (172mph).
Military jet: A military jet lands at an average speed of approximately 175 knots (200 mph)

Note that during crosswinds (when winds are not parallel to or directly with/against the line of travel), a plane may land faster to ensure a safer landing.

How Fast Planes Descend When Landing

Typically, at around 100 to 120 miles from the destination airport, an airliner will begin its descent. However, this can vary depending on cruise altitude, weather conditions, and the amount of traffic heading to the same destination.

An airliner will typically begin its descent at a cruising altitude of 30,000 feet at 3,000 feet per minute.

As it reaches 10,000 feet and below, a speed restriction of 250 knots is enforced, reducing the descent to a speed of approximately 1,500 feet per minute.

When 10-15 miles from the destination, the airliner will slow to landing speed. When 5 miles from the runway, the slats and flaps are extended, reducing the airplane to its approach speed.

On average, it takes 30 minutes from the time a plane starts its descent to landing on the runway.

Related: What Do Flaps Do on Planes?

Why It Sometimes Feels Like the Plane is Speeding Up Before Landing

This occurs because as you sit in your seat there is a feeling that your seat is being accelerated forwards into you.

However, during the transition phase between the final approach and the touchdown, what is actually happening is that gravity acts, so you are actually being accelerated downwards into your seat.

Sometimes it can feel like a plane speeds up before it lands because it actually is. Adding power just before touchdown can result in a smoother landing.

Landing is More Dangerous than Taking Off

There’s no doubt that landing is not only more dangerous than takeoff but that it is also the most dangerous part of any flight – and there are statistics to prove it.

According to Boeing , 49% of all fatal aircraft accidents occur during the final descent and landing phases of a fight, compared to 14% at takeoff.

Why is this?

Well, not only does a pilot have to deal with communicating with air traffic control, making sure they line up with the runway just right, and keep the crew informed, but they have to do these things while descending at over 100 miles per hour.

There is also very little margin for error when landing, and the weather, like high winds, has more of an impact when trying to land than during takeoff or when cruising.

Helen Krasner

Helen Krasner holds a PPL(A), with 15 years experience flying fixed-wing aircraft; a PPL(H), with 13 years experience flying helicopters; and a CPL(H), Helicopter Instructor Rating, with 12 years working as a helicopter instructor.

Helen is an accomplished aviation writer with 12 years of experience, having authored several books and published numerous articles while also serving as the Editor of the BWPA (British Women Pilots Association) newsletter, with her excellent work having been recognized with her nomination of the “Aviation Journalist of the Year” award.

Helen has won the “Dawn to Dusk” International Flying Competition, along with the best all-female competitors, three times with her copilot.

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KTAS: Knots True Airspeed and What It Means

by Chris | Sep 10, 2017 | Private Jets , Travel Tips

If you take planes often, it’s easy to become interested in how they work. Knowing the specifics gives nervous flyers peace of mind while others who love flying want to know as much as possible.

Either way, we have you covered. In this article, we’re explaining KTAS which is pilot lingo for how fast planes fly.

If you want to know more about how planes speed through the air, read on below.

Knots True Airspeed or KTAS

KTAS is the abbreviation for knots true airspeed, a unit of speed measurement. The knots true airspeed tells pilots how fast the plane is going in relation to the air around it. The speed changes based on air pressure, temperature, and weather.

Pilots use knots true airspeed to calculate flight plans, fuel costs and needs, and navigation. In the private plane industry , it’s a factor in calculating flight price. Knots TAS is the equivalent speed of how fast a plane would go on the ground. It’s essentially a planes MPH, measured in knots.

What is a Knot?

A knot is a unit of measurement for large vessels like planes and ships. It’s slightly different from MPH, but not by much. The difference is knots measure speed in nautical miles per hour, instead of normal miles.

One nautical mile per hour equals 1.15 normal miles per hour. The practice of using a different mph system is very old. Before speed indicators were invented, sailors would drag ropes with knots on them behind their boats to measure speed.

Since they’re exactly the same but with a .15 mile length change, why use a different system? Because boats and planes measure distance on lines of latitude and longitude. One nautical mile (knot) is 1 minute of an arc on any line of longitude.

Latitude goes horizontally across the globe, creating lines like LATter rungs. Longitude crosses the globe from pole to pole.

KTAS vs IAS

Knots true airspeed is different than indicated airspeed. KTAS doesn’t account for changes in pressure, while IAS (indicated airspeed) does. Knots true airspeed calculates the speed of the plane without environmental interference, while IAS measures the speed with it.

IAS and knots TAS are similar at low altitude and pressure levels, like at temperate sea level. As the plane rises into the air, it passes through different levels of pressure. IAS measures the degree to which the air pressure is slowing down the plane.

Since it accounts for pressure, IAS will always be lower than the knots true airspeed at higher speeds/altitudes.

Wrapping Up

Knots true airspeed is the way pilots measure nautical miles per hour. It tells them what to plan for time and fuel wise, while IAS is the ever-changing reality.

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True Airspeed Calculator

Table of contents

The true airspeed calculator will help you calculate the true airspeed of an airplane. What is true airspeed, you might ask? Since the Wright-Flyer's first flight in 1903, air travel has become one of the most important modes of mass transport around the globe. Improvements in aeronautical engineering technology have brought with it many new concepts never used considered, one of them being true airspeed (or TAS for short).

There is a relative difference between how fast an airplane moves in the air (true airspeed) and how fast it goes with respect to land. Knowing how to find true airspeed becomes very important for pilots. Read on to find a discussion about how to calculate true airspeed and dive into the various true airspeed formulas.

What is true airspeed?

You can understand the true airspeed as the speed at which an aircraft travels relative to the air that it is in . Airplanes often fly at high altitudes, where the air is much less dense. This reduces the air resistance/drag which the airplane encounters, which may mean less fuel required to complete the journey than at a lower altitude. The true airspeed is also an integral piece of information for the precise navigation of an aircraft.

Traditionally, the true airspeed was found indirectly using an airspeed indicator, but now GPS makes such measurements obsolete. Most aircraft now measure Indicated Airspeed (or IAS ) instead (calculated directly from an airspeed indicator). This is because the IAS is a better indicator of power used and lift available.

How to calculate true airspeed?

Now that we have understood what true airspeed is, we can move to the next stage and see how to calculate true airspeed. Depending on the information present, we will use a different TAS formula. They are discussed below :

The first TAS formula discussed uses a rule-of-thumb approximation using only the altitude of the airplane.

TAS = (IAS * OAT * A / 1000) + IAS

OAT - Outside Air Temperature correction term. We use it to take into account the temperature conditions prevalent in the air the airplane is in;
A - Altitude of the airplane; and
TAS & IAS - True airspeed and indicated airspeed, respectively.

The second true airspeed formula used makes this a true airspeed to the ground speed calculator :

GS = TAS + W * cos θ

GS - Ground speed;
W - Wind speed; and
θ - Angle between the wind direction and aircraft's motion.

The third method uses the values of altimeter setting , altitude , and calibrated airspeed (CAS) or indicated airspeed (IAS) to calculate true airspeed. We use the true airspeed formulas described in the Aviation Formulary by Ed Williams.

The last method also calculates the Mach number of the aircraft, pressure altitude (equivalent altitude according to ISA - International Standard Atmosphere), and the density altitude (ISA defined atmospheric region based on temperature and pressure).

How to use the true airspeed calculator?

Now that you have a basic idea of true airspeed, it's time to put the calculator into use. Follow the simple instructions below and get your true airspeed calculations going:

Understand which formula is correct.

Which measurements do you have with you? According to the information you have, decide which method is best for you to use. All of them will show you how to find true airspeed, but they calculate it in different ways.

The first method (using IAS and altitude)

All you need to do is enter the values of IAS , the altitude the plane is flying at, and the OAT Correction . You can also use the calculator to figure out other values when you input true airspeed first.

The second method (using ground speed and wind speed)

You can use the second method as a ground speed to the true airspeed calculator. Type in ground speed, wind speed, and the angle the wind makes with the plane to find the TAS.

The third calculator (based on the E6B flight computer)

Enter the values for indicated altitude , altimeter setting , actual temperature , and calibrated airspeed or indicated airspeed in the boxes. The calculator will give the values of TAS, density altitude, pressure altitude, and Mach number.

Ensure that you use the right units.

One of the most common mistakes made by students (and teachers 😜) is to forget to use the appropriate units. Airplane speeds (unlike other objects in motion) are almost always reported in instead of km/h or mph. Make sure you have selected the correct units! Use the dropdown menu at the right of the box to change them.

Speed conversion If you need a hand with speed conversions, our knots to mph converter might be handy.

Long calculations? Save and lock in the values!

Click on the gray region beside the input boxes to reveal the lock and save options. Use them in case you expect some values to come up repeatedly.

Now that you know how to find true airspeed, feel free to go ahead and check out some of our other fun and interesting tools, like our flight radiation calculator or rocket thrust calculator !

Indicated altitude

Altimeter setting

Actual temperature

Calibrated/indicated airspeed

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Pressure altitude

Density altitude

Mach number

True airspeed

Additional parameters

Sound speed

Standard temperature

Pressure altitude correction

How Windy Does It Have to Be Before Planes Can't Take Off?

Severe winds have been gusting across New England and the mid-Atlantic, causing flight delays and even cancellations . At New York-JFK, pilots and airlines received this data to review during their preflight preparations:

The output shows plenty of visibility, blue skies and no thunderstorms (or snowstorms, for that matter). However, it's a touch windy, with gusts up to 56 miles per hour. That's going to stir up all sorts of dust and trash on the New York City streets. But for our pilots and their aircraft? It all depends on the aircraft — and the direction of the wind.

It's the Crosswinds That Pilots Look for

The real issue with wind isn't the speed of the wind per se — it's the component of the wind that's blowing across the runway in use. Planes like to take off into the wind, because it's the only thing in aviation that's free and provides lift. When air flows over the wings, flight happens, and the wind helps with that during take off.

Runways are designed and built to point into the so-called "prevailing wind," as determined by studies observing the wind in a particular area. You'll notice that at Los Angeles (LAX), every runway is pointing toward or away from the ocean. At Chicago-O'Hare (ORD), there are enough runways for air traffic control to adjust to many possible wind orientations.

Mother Nature, however, doesn't really care. She'll put the wind any which way, and in most cases at an angle to the centerline of the runway. The angle formed between the wind and the runway centerline is defined as crosswind. And there are limits to that component, as well as to tailwinds.

Every aircraft has its own stated crosswind limitations. The Boeing 737, for example, has a maximum crosswind component of 35 knots if the runway is perfectly dry, or 15 knots if the runway is wet. The larger Boeing 777 has a maximum crosswind component of 38 knots. This doesn't necessarily mean that the pilots and airport operations teams will decide to get underway if the winds are at those limits or close to them; airlines may very well impose lower crosswind limitations below the stated manufacturer's limits.

Airports, too can impose limitations. One widely-cited airport is London City Airport (LCY). There, the runway is only around 100 feet wide, compared to 150 or 200 feet at JFK. Accordingly, the maximum acceptable crosswind component is 25 knots.

"These calculations are performed on the airplane in our flight management system," a commercial pilot for a US carrier told TPG in an email.

"We have limitations on the aircraft that can't be exceeded. For instance, we have a limitation on my airplane that our maximum takeoff and landing tailwind component can't exceed 10 knots. We have one for [instrument approaches in low visibility] in which the maximum crosswind component is 15 knots," the pilot said.

"So, we input the weather and runway condition into the computer for the specific runway we plan to land on and the computer will come back with our landing speeds and the wind component for the runway. If it exceeds our limitations, then we don't attempt the approach or takeoff."

Calculating Limitations

At JFK on Monday, at the time of this writing, the wind is coming from 290 degrees, and the runway in use for takeoffs is oriented to 310 degrees. (Without getting too much into the detail, the wind is displayed as a true heading, whereas the runway is oriented to a magnetic heading But I digress.)

Ignoring the gust factor for a moment, the headwind is 18 knots and the crosswind component is 10 knots. Even adding a gust factor of 49 knots — which is substantial — only 13 knots of that wind is part of a crosswind. The rest is just Mother Nature giving our aircraft more lift, more or less blowing straight down the runway. Our plane sitting at the approach end to runway 31L, at the end of the blue arrow, is ready to roll.

Now, let's say runways 31L and the parallel 31R were shut down for some reason, and the only available runway for takeoffs was runway 22R — where you see the second plane waiting to take off. That aircraft faces a crosswind component of 26 knots and a headwind of two knots — the wind is almost perpendicular and blowing hard. If you add the gust factor bringing this up to 49 knots, the cross wind component jumps to 36 knots, exceeding the limitations of the aircraft and likely far exceeding the limitations of the airline.

And what about even windier conditions?

Aircraft do have an additional limitation in terms of wind, and that is to open or close the aircraft passenger and cargo doors. Typically, the wind should not exceed 45 knots.

So why are so many New York City airports facing wind delays today? This is likely due to safety concerns for ground crew.

Mike Arnot is the founder of Boarding Pass NYC , a New York-based travel brand, and a private pilot who flies with a maximum crosswind component of only a few knots.

Why Do Boats & Planes Use Knots? You Won’t Leave Confused!

Hearing the question and wondering why boats and planes use knots. Became an endless search for a clear reason on why, and how in the world to understand it without all of the numbers!

Why Do Boats & Planes Use Knots? Boats & Planes calculate speed in knots because it is equal to one nautical mile. Nautical miles are used because they are equal to a specific distance measured around the Earth. Since the Earth is circular, the nautical mile allows for the curvature of the Earth and the distance that can be traveled in one minute.

If you have searched around for this and noticed that you end up watching a video or leaving the article confused. Read this easy to understand breakdown!

What’s The Difference Between A Mile, Kilometer, and Nautical Mile?

These are the 3 most common ways that distance is measured. In the United States, distance and speed is measured in miles. This system is called the imperial system or statute system.

In almost everywhere else in the world, kilometers are used. Which is called the metric system. Distance and speed is calculated using the metric system which is a little different than the imperial units measurement.

A mile is a little longer than a kilometer. One mile is 5,280 feet which is equal to about 1,609 meters or 1.6 kilometers. Which is why when Americans go to other countries and drive around. It is odd for them to see 120km on the speedometer of the car!

Now a nautical mile is a completely different thing all together. A nautical mile is a measurement that is based on the circumference of the Earth. To really get it, we will have to understand a little more about Longitude and Latitude.

For now though, just know that a nautical mile is “one minute” of latitude.

Calculating Speed

The same goes for the kilometer. Traveling 20 kmh means you will travel 20 kilometers in one hour, if you are going 20 kmh.

Nautical miles, on the other hand, is still based on the per hour system, but is calculated in knots.

Traveling one nautical mile means that your speed is one “knot” per hour. As time continues to go on. In the boating world, knots are starting to disappear with the advancement in marine electronics. As well as our laziness as boaters!

Most GPS systems and chartplotters allow the user to change the units which it displays. Allowing most people to select mph or kph. So they never really have to know the nautical mile system.

Sailers and airplane pilots on the other hand. Still use the knots system because of the navigation and precision of the system. Being based on the layout of a chart which has the longitude and latitude lines accross the map.

Allows for more accurate calculations and exact locations of where they are located. In case there is an emergency, whoever is coming to help them can find them more easily.

Remember The Difference Between Longitude & Latitude

Having exact locations for where a boat or plane full of people are, is extremely important! Making sure that their location can be pinpointed on a map can mean the difference between life and death .

If you look at your phone and bring up Google Maps. The GPS position of that phone will pinpoint exactly where you are on a map. Which is great when you have the phone, it has service, and the battery is fully charged!

When talking about locating a boat or a plane. The same GPS system is used with the GPS coordinates, but those coordinates are based off of the different numbers of longitude and latitude.

Since the Earth is a globe and the equator is the middle section of that globe. Everything goes off of that and the Prime Meridian which is the starting point for the numbers. The equator starts the latitude numbers off with 0.

When looking at a navigational chart, which is what is used in both aviation and seagoing vessels. The equator is 0 and then as you move up the chart from there the numbers go up. Then if you look below the equator, the numbers will be negative numbers.

The lines going up and down on the map are the longitude lines. They start with the prime meridian and then work their way around the circumfrance of the Earth until they get back to where they started.

This prime meridian mark is also where the beginning of the time zones start.

Thinking Of The World As A Graph

Think about it like this, the equator is the horizontal line around the center of the graph. The word latitude is like ladder. Latitude, ladder, they both go up and down, or well, you can go up and down on the ladder!

So knowing that all of the horizontal lines marks our latitude and the beginning is the equator. If you go North up the ladder each line is called a “degree” with the description of North. There are 90 degrees until we hit the north pole. So if you were on line 50, it would be 50 degrees North.

The same goes for the South. Starting at 0 degrees for the equator. We work our way down the ladder of degrees until we hit 90 degrees South, or the south pole.

The vertical lines start at 0 at Greenwich England. From there they count 360 degrees going to the west until they come back around to England and the starting point of 0.

These lines cross each other making all kinds of boxes which give an exact location on the Earth. These locations, with their numbers are where we get the GPS coordinates.

Understanding A Nautical Mile Calculation

It isn’t really necessary to understand this completely in and out, but it would be good to know if you would like to study it out further. For the time here, we are more focused on why boats and planes use knots and Nautical miles.

Given that we understand the graphing of the Earth to get us the GPS coordinates. We need to know why Nautical miles are different than normal miles or kilometers.

They are different because of the curvature of the Earth. Since our graph of boxes will slightly bend a little bit as we get to either the North or South poles. There needs to be a correction for when we are traveling accross massive amounts of the Earth.

Since the Earth is more of an oval, there are larger sections of the graph when we are closer to the equator. The sections at the poles are smaller.

This is where it gets a little tricky and confusing for all of us. The introduction of the degrees is where we need to focus our attention. Since the Earth is 360 degrees from the starting longitude and going all the way around the Earth back to it.

We can break that down into a distance.

Counting the longitude lines around the Earth and dividing that by “360 degrees.” This is where we get the distance of 1 degree which is 6,080 feet. That was the original distance of a Nautical mile.

When we look at the same thing only with the latitude lines. We notice that the distance changes because the Earth is not a completly perfect circle. So there is a correction where the distance at the poles is 6,110 feet and then at the equator it is 6,050 feet.

Seeing that there is a 60 foot difference between the two, when it is cut in half the distance is 6,080 feet. The math can get way more complicated than that, but for me and laymens terms on how I understand it. This is the way it looks to me!

Today they have it pinpointed down to 6,076 feet or 1.15 miles.

Where Did The Term “Knots” Come From?

So when traveling through the air or on the sea, calculating your speed in knots means you are calculating the nautical miles you are going.

The term “knots” came from about the 16th and 17th century. Captains and sailors would use what is called common logging. Where they would take a line and tie knots in the line with the knots measured specifically apart from each other.

They would tie a piece of wood to the end of the rope and then leave the line coiled up on the back of the boat.

While watching an hourglass, which was about 30 seconds. They would let the peice of wood into the water and let it float behind the boat pulling the line out.

When the hourglass had ran it’s course, they would pull the wood in and count the knots that had been pulled out. Giving them the speed at which they were traveling.

Whether it be 2, 3, 4, or however many knots where pulled out! The term has stuck since then and is still used among pilots and captains all over the world!

Check Us Out!

Hopefully this gives you a clearer understanding of the term knots and why nautical miles are used over regular miles! If you have any questions, ask us in the comment section below!

Then we’d like to invite you to Check us out on our Youtube Channel: Born Again Boating! We make all kinds of how to and DIY boating videos. Along with outboard service helpful tutorial videos as well!

Get subscribed to the channel and add us to your favorites so we can become your go to resource for when it comes to finishing all of your outboard and boating projects!

Aaron Hilligoss

Aaron has been working in the Marine Industry for over a decade and holds certifications for Yamaha and Mercury Marine. It is not uncommon for him to own and be working on at least three different boats at any given point in time!

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How Fast A Plane Do You Need?

We all love big numbers, but how important are high cruise speeds to your missions? As it turns out, they’re critical.

By Isabel Goyer Updated August 10, 2021 Save Article

When we look to buy a new plane, well, at least a plane that’s new to us, we often look first and longest at how fast it is. Our love of speed, and I’m right there with you on this one, is a complicated one. Planes that go really fast are really expensive to buy and drive. What’s my dream plane? Well, for going places, I’d say it’s probably the Gulfstream G650. But at a cool $70 million, that continent-hopping beauty is just outside my price range, so I’d have to aim a bit lower. A more pertinent question might be, should I get a Beechcraft Bonanza or a Cessna Skylane?

You can look at a few key specs, but specifications are nothing without putting them into the context of what your needs are. What kind of missions do you fly? How far do you go? For what reasons? With how many people aboard? And what about bags? And what kinds of fields do you land on? When you ask these kinds of questions, it becomes clear that speed, while important, is just one of a range of intersecting capabilities that all go toward figuring out what plane is right for you. Is speed all that important? You bet it is!

But speed is not always well understood, and by that, I mean it’s not immediately clear to many pilots (especially those who haven’t flown long cross missions–we’re talking 750 nm or more on a regular basis) what speed means in practical terms.

Before I go any further, I want to add that the basis for this article was one by a previous contributor to our title, Budd Davisson. It was a good read, and well researched, too, but as I began to add my two cents to it, it soon became clear that our perspectives and directions were somewhat different. So consider this article me leapfrogging off of Budd’s good ideas and direction but adding my perspective.

“The big question remains: What does speed mean in real terms? What kind of advantages do those fast movers enjoy, and is it worth what you have to pay to get it?” googletag.cmd.push(function() {googletag.display('in-content-1');})

One thing Budd mentioned was that there were benchmarks for speed, and they’re useful. Twenty-five years ago, that was 200 mph, a figure made famous by Mooney, which leveraged that magic number by calling one of its planes the “201” for being even slightly faster than that nice round 200 mph.

And for the sake of standardization, Plane & Pilot has adopted the FAA’s knots-first editorial policy, which has been an industry standard for the past 35 years. And when we discuss speeds, whether mph or knots, we’re referring to true airspeed (technically abbreviated as “ktas”), which is the plane’s speed through the air, calculated from the calibrated airspeed and adjusting for the variables of air density and temperature. So in terms of that 200-mph gold standard, we’ll think of it as 175 knots. Which is still really cooking.

THE MEANING OF SPEED The big question remains, though. What does speed mean in real terms? What kind of advantages do those fast movers enjoy, and is it worth what you have to pay to get it?

The answers are, there are a lot of advantages, some big, some not so big, and the costs can be great. Can they be too great? Good question. Let’s look at some real-world cases.

But first, it’s important to get a grasp on your typical mission. If your prime travel distance is, for the sake of choosing a round number, 500 nautical miles, then one could make a compelling argument that you don’t need a 175-knot cruiser to make that trip reliably and regularly. But unless you’re changing zip codes or delivering a plane to a new owner, cross-country trips don’t end at the first fuel stop. They don’t even end at what we think of as the “destination.” The actual destination is, in fact, almost always back home.

If you’re making a multi-day trip, which, regardless of how fast the plane is, most long cross countries will be, then you can treat the mission as two separate trips on two separate days. Fair enough.

But if you’re planning to be home again that evening, then speed is an even more critical part of the calculus. In fact, without a fast plane, a 500-nm trip out and back again with three hours on the ground at the destination isn’t doable in daylight in most of the lower 48 United States during the daylight available most of the year. And super long days with a trip home late in the evening almost guarantees less-than-optimal human performance on those last legs.

But in terms of the simple math, again with that 500- mile trip, which is a usable average for most pilots, how much does speed get you? What’s the difference between cruising at 138 knots, something that most Cessna 182s can do, and 174 knots, something that most mid-’60s to present-day Beech Bonanzas can pull off?

That calculation really is easy. The Bonanza saves right around 45 minutes on that trip. Is saving three-quarters of an hour worth the extra dough that sweet Beechcraft will cost you, both upfront and going forward?

The answer is maybe. Things are a lot more complicated than a cursory look at block time on one leg can tell. Real-world cross-country flying is all about taking all the parameters into account, and that means looking realistically at weather, optimum altitudes, passenger needs and the amount of daylight you have to work with—winter days are short. And when you begin factoring in considerations such as required alternates on an IFR flight plan or thunderstorm diversions, the process can get complicated, and pilots need to have a solid grasp of all of the variables that go into planning any particular trip. So, is the extra speed worth it? In the small picture, maybe not. But when you take a wider view of cross-country flying, the additional speed is priceless.

HOW FAST, THEN? Airplanes as fast as that legendary 200 mph (which we’ll think of here as 175 knots) always have the increased maintenance of retractable gear and big motors, and almost always have higher acquisition costs. Within the traditional general aviation fleet, however, there are actually only a few airplanes that can honestly claim to cruise 200 mph. These include some Cirrus SR22s, later Bonanzas, some M20-series Mooneys, some Cessna Centurions and a few others. The big question is, how much time is extra speed actually saving you, and is it worth the additional expense and potential hassle?

In the simplest and least-useful terms, we might translate that as, how much are those 40 minutes worth? If you say that flying 130 to 140 knots will do, what’s in it for you? A lot. The most obvious advantage is that it costs less to get into the game to begin with. Even though the legendary Cessna Skylane is getting to be more expensive all the time, it’s still cheaper than most of its much faster neighbors. An older Skylane will give you 140 knots for around 12 gph. So you’ll pay less for the plane, less for fuel, less for maintenance (if you’re lucky) and less for insurance.

One way of looking at speed is by using, instead of nautical miles per hour, a figure that is dollars per hour. If that sounds too complicated to be useful, we agree with you, mostly. You can estimate costs for operating any aircraft, though when it comes to maintenance, the cost variability of small planes is great. In general, the slower a plane is, the cheaper it will be to operate.

HOW MUCH DOES FAST COST, THOUGH? The converse is true. Planes that can flirt with that 175- knot figure will cost you more upfront, more in gas and oil, and more going forward. Most of these planes are retractable gear models, though the advent of fixed-gear fast glass models, like the Cirrus SR22, have changed that calculus some.

By taking the projected costs of a plane to own and operate, known as fixed and operating costs, you can figure out how much it costs you to fly per mile. (If you wanted to get really fancy, you could make that “seat miles,” which takes into account the number of people you can take along with you.) But for small planes, miles per gallon works well.

Conventional fixed-gear singles with bigger motors will net you around 12 mpg. Mooneys are champs in the fuel efficiency arena. Because they’re smaller, both outside and in, and because they have lower drag because of their size and smart aerodynamic design, the less-thirsty, smaller engines up front can get you around 20 mpg, which is way better than most of the SUVs we drive.

Another way to look at speed is how much we have to pay for each additional mile per hour of speed when buying the airplane. Even when using bluebook aircraft values, which are usually low, as comparisons, it shows that airplanes like the Bonanza, which are much larger and more luxurious but nowhere nearly as efficient as the Mooneys, command higher prices. Therefore, on a dollar-per-knot basis, they’re much more expensive, plus they’re way down in the fuel-efficiency curve. So why do people buy Bonanzas over Mooneys? Clearly because they value that comfort and are willing to burn more gas to get it.

That doesn’t answer the question about speed, though, just what you’re going to pay for it. Let’s say instead that you’re basing your purchase on fulfilling a particular mission profile, and you’ll pay whatever you need to get that plane—within reason, of course. How do you wrap your head around the speed-versus-cost equation?

I’d suggest thinking of piston singles in six groups.

â¢ Planes that can’t make 125 knots. These include almost every two-seater, many of which can’t even hit 100 knots reliably. â¢ 125-knot cruisers. Included here are planes like 180-hp Cessna Skyhawks and Piper Archers, among many others. â¢ Those that can cruise at around 140 knots. This group includes Skylanes old and new, Piper Dakotas (235-hp PA-28s), the Diamond DA-40 and the Cirrus SR20, along with many older Mooneys. â¢ Models that can reliably do 160 knots, such as the Piper PA-32 Saratoga RG or the Cessna 182 RG. â¢ Speedier ones that can deliver 175 knots, such as normally aspirated Cessna 210s, many Bonanzas, more powerful Mooneys, and a few others. It’s not a long list. â¢ And then, sleek and powerful models that can get you 200 knots. These are usually turbocharged and deliver such speeds at higher altitudes, typically in the mid-teens.

By referring to this list, you should be able to get a solid idea of what kind of plane you’d want if you were regularly flying long cross-country legs. For trips of 500 nm, I’d say you want at least a tier-two level plane. For anything longer, I’d suggest an airplane that will give you 140 knots. If you’re flying really long cross countries on a regular basis, aim for getting at least 160 knots, though faster is even better. Here’s why.

RANGE: THE GREAT EQUALIZER, UP TO A POINT With all this talk of speed, there’s one other factor that has to be tossed into the decision equation: range. How far will a plane go without making a fuel stop? When we’re talking 500-mile trips, that’s not usually a factor because just about everything on our list has at least 500 nm of range. But a funny thing happens when we stretch that trip out to 1,200 miles. Suddenly, fuel capacity becomes a really big deal.

Let’s say you’re flying an early 2000s Cirrus SR22 that delivers its advertised 180 kt cruise speed, and let’s round down to 175 to be conservative. Its spec sheet says its range is better than 1,000 nautical, but manufacturers often (almost always, in fact) list range figures based on best economy power settings, which turn a 180-knot airplane into a 140-knot one. It should go without saying that no one flies their SR22s like that unless they’re trying to prove a point or flying long overwater legs. So, with 1,200 nautical miles between departure and destination points, that’s just a two-leg affair—two long legs, granted, but it’s undoable for 125-knot cruisers, and it’s biting off a lot even for 140-knot models.

That’s because, for planes with less fuel capacity/range than the Cirrus in order to make 1,200 miles safely and still have some reserve, you would have to stop twice to get gas. The actual time in the air would be around seven hours. Two fuel stops, however, are going to add 30 to 45 minutes per stop, for a total of around eight hours departure to destination.

For a trip of 1,000 miles, a 700-nm-range, 175-knot plane looks great. Adding in that fuel stop on a long mission is a killer, so planes with extra fuel capacity, like some newer SR22s or Mooneys, make long hard days a little less of both. That’s worth a lot.

Still, back to that hypothetical 1,200-mile trip. Now, let’s say your lowly Cessna 182 is plodding along at 140 kts but burning significantly less gas. More importantly, it’s a newer model with 88-gallon tanks, which, according to the specifications, give just under 800 nm of range. So, it easily can make it with only one stop. Eight and a half hours of flying, plus 45 minutes of ground time, gives you around 9 hours and 15 minutes elapsed time. So, the SR22 gets you there about there 55 minutes faster. But are all of those things a really big deal on such a long trip?

SHORT-DAY CALCULUS They are, especially when you’re flying in the winter. Take Kansas City, for instance, since it’s as mid-continental as you can get. On the shortest day of the year there, you have just over nine hours from sunrise to sunset. Add another 45 minutes or so of workable light, and you’re talking 10 hours of travel time if you get started as early as possible, which isn’t always easy. The faster plane gets you there with daylight to spare even on the shortest day of the year, so long as you’re not flying way up north.

Now let’s interject a scary word when you’re flying long cross countries: headwinds. And let’s use an average bad- day headwind, 25 knots. In the 175-knot airplane, you’re still getting what is essentially Skylane no-wind performance. In the Skylane, you’re getting sub-Skyhawk levels. In the faster plane, the trip is long but still doable within the daylight you have to work with. In the slower plane, it’s not.

When it comes to multiple legs, even short ones, and wind and weather, extra speed can make a huge difference. A flight of 400 nm won’t require a fuel stop for any of these planes, but the time saved flying a much faster airplane will translate into not just one faster trip but potentially three, or maybe four. Getting back home a couple of hours earlier, or maybe just getting back home at all instead of having to hotel it at the last stop, is worth a lot.

SO, WHAT’S FAST ENOUGH? So, in the end, how fast is fast enough? Again, it depends on your typical mission. For pilots who are going to fly 750 trips or shorter, any plane that can deliver around 140 knots is a good bet. But if you increase the distance and add in the greater chance for weather and wind playing havoc with your plans, the calculus gets more complex. To decide, you’ve got to consider the interplay between the pilot/owner’s wants and needs, as well as their financial wherewithal as it relates to the aircraft in your economic wheelhouse. When in doubt, if you can use, afford and fly it, go for the faster plane.

In the less-than-perfect world we all live in, sometimes the decision will mean buying a plane that’s not quite as fast or rangy as you wish it were. If that’s the case, you need to recalibrate. Take an extra day for those longest flights. Or fly commercial if you must—nobody flies their Bonanza from New York to Paris these days. The point is, even if your ride isn’t as fast as you’d like, you still get to fly your plane on all but the longest cross countries.

But, again, if you can afford it, speed delivers in so many ways. PP

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Flying time between cities.

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Time from a Distance in Nautical Miles and Speed in Knots

Calculate the time it takes to travel a certain distance in nautical miles based on a speed in knots. A knot is a unit of speed equal to one nautical mile per hour. The symbol used for a knot is kn or kt.

Time from Speed and Distance Knots/Nautical Miles

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Beriev Be-2500: What Should You Know About The Proposed Super Heavy Amphibian Ground Effect Plane?

Soviets led in developing ekranoplans.
Beriev Be-2500 Neptun could be heaviest plane ever.
Ekranoplans offer unique benefits if constraints are overcome.

Ekranoplans are a sort of mix of an aircraft and a hovercraft using ground effect to fly or skim a few meters above the ground (normally the water). It is sometimes assumed that the Soviets just copied Western aircraft design (such as with the Tupolev Tu-4 - a B-29 copy) and were always playing catch-up.

But this is just wrong (or at least isn't always right). The Soviets pioneered ground effect vehicles (GEV) or ekranoplans and built remarkable ekranoplans like the Caspian Sea Monster . Perhaps the most eye-catching proposed Russian ekranoplan is the Beriev Be-2500 Neptun.

Beriev Be-2500 Neptun

The Soviet Union may be long over, but Russia has continued to tout the idea from time to time. One of the more recent post-Cold War proposed ekranoplan designs is the Beriev Be-2500 Neptun, developed by Beriev (Beriev has also built the world's only amphibious jet aircraft, the Be-200 ).

The design of the Be-2500 is incredible. The maximum takeoff weight is estimated at 2500 tons (hence the name 'Be-2500'). If ekronoplans were to be considered aircraft and if they were ever built, they would be the largest aircraft in existence, weighing four times more than the now-destroyed Anotonov An-225.

It would be something of a flying ship. As well as flying at high altitudes on long trips, the Be-2500 would be designed to travel intercontinental routes across the sea. It wouldn't require any special infrastructure to dock.

Air Forces (writing in 2010) stated the project would cost between $10 and $15 billion to realize. However, it seems the Be-2500 remains a pipe dream. Little or nothing has been reported on its development over the last 15 years.

Russia is now embroiled in its disastrous full-scale Invasion of Ukraine and its limited resources are likely to be channeled to the war effort and not grand projects like the Be-2500.

How Do Propellers Work To Lift Aircraft Off The Ground?

Ground effect.

Ground effect is the reduced aerodynamic drag that fixed-wing aircraft's wings generate as they are close to the surface (ground or water). Ground effect occurs when an aircraft flies closer to the ground than the length of its wingspan. The profile of the wing deflects the air downwards, compressing the air and creating an area of higher-than-normal air pressure.

Passengers can feel the ground effect when flying on commercial airliners. Just before the aircraft's wheels touch down, there is a feeling of the aircraft hitting a sort of air cushion. This is the air being squeezed under the aircraft's wings, creating lift.

When Boats Fly: 5 Remarkable Ekranoplans You Need To Know About

Advantages and disadvantages.

Building aircraft to utilize the ground effect has a range of benefits and costs. One of the great disadvantages of ekronoplans is that they are so close to the water surface. This means there is a great danger of collisions with surface objects (like ships and boats), and pilots have few options to avoid collisions.

The low level of the ekronoplan also means the pilots have low visibility. Ekranoplans can't fly during periods of high winds and large waves.

But, if the disadvantages could be overcome, a militarized ekronoplan could approach enemy ships at high speeds under the radar. It could avoid sea mines and enemy torpedos. It could also carry massive loads (perhaps up to 1,000 tonnes) across the oceans at the speed of a slower cargo plane but much faster than a ship.

The Germans, Chinese, Americans, and others have all experimented with developing ekranoplans. If the challenges can be overcome, the advantages are enormous. While the Soviets largely designed ekranoplans for military use, small ferry-like ekranoplans are being developed today. One example is the AirFish 8, designed to carry 6–8 passengers skimming at 80 knots over the surface.

Boeing once revealed the Boeing Pelican concept, which would have transported 17 M1 Abrams tanks across the ocean. It would have been the largest ekranoplan or aircraft ever built. But Congress rejected the plans in 2005, as there just wasn't a need for such a plane at that point.

Beriev Be-2500: What Should You Know About The Proposed Super Heavy Amphibian Ground Effect Plane?

NEWS... BUT NOT AS YOU KNOW IT

Flight attendant reveals alphabet hack to prevent blood clots on planes

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Portrait of young woman in plane illuminated with sunset light

There’s nothing better than settling in for a long-haul flight knowing you’re going somewhere super exciting.

You’ve got your snacks, a few Netflix shows downloaded and, crucially, an eye mask, ready to settle in for the coming hours.

But when it comes to flying, safety is paramount : the pressure can increase the risk of developing a deep vein thrombosis (AKA, a blood clot in a vein), particularly on flights that are longer than four hours.

So, the next time you jet off, consider building the ‘alphabet’ hack into your routine to prevent clotting and keep your mind at ease. It’s easy to remember (and if you forget, you can sing along the alphabet song as you practise it).

‘To prevent blood clots during long flights, consider incorporating a few simple strategies,’ TikToker @ciciinthesky, who is a flight attendant and often shares travel tips and inspiration to her account, explains.

‘First, remember the alphabet exercise – trace each letter with your foot to promote circulation,’ CiCi outlines in one video.

‘Second, wear compression socks, which help maintain blood flow and reduce the risk of deep vein thrombosis (DVT).

‘Finally, make it a point to stand up and walk around every hour or so if possible. This helps activate your leg muscles, encouraging blood to flow more freely.

‘Combining these techniques not only enhances your comfort but also significantly lowers the risk of developing blood clots during extended periods of inactivity.’

This is why we always board flights to the left side of the plane

When boarding a plane, you’ll always enter on the left side of the aircraft, regardless of the carrier, whether you take stairs or a jet bridge, or whether you’re in economy, business or first class.

There’s an interesting reason behind it too. Commercial aeroplanes were initally build with their passenger doors on the left because of historical traditions, before it became a matter of efficiency.

Michael Oakley, managing editor of The Aviation Historian , explained to Afar : ‘Much of aviation terminology had its origins in maritime lore (rudder, cockpit, cabin, bulkhead, knots, etc), and similarly, the aeronautical ways of doing things owe a lot to sailing.

‘Just as boats and ships have a port side – the side of the vessel conventionally adjacent to the dock when in port – aircraft are the same. Sensibly, people decided to continue to board on the port (or left) side.’

So, when it comes to compression socks, which ones should you go for?

You can pick them up for a relatively low price in Boots, at £13.68 , whether you buy ahead of your flight or leave it to the last minute at the in-airport shop. Gatwick, Luton, Stansted and Heathrow all have a Boots store, ready and waiting for those ‘oops, I forgot’ moments ahead of boarding.

If you want to plan ahead and save a little bit of money, though, you can buy them on Amazon for as little as £7.99.

There’s also the option of having fun, colourful socks, too: autism and sensory-friendly, there are an array of options available through Not Your Grandma’s, including a fun space print , dinosaurs or even unicorns , for £15 a pop.

Your Daily Horoscope

Daily horoscope today: May 17, 2024 astrological predictions for your star sign

‘Wearing compression socks reduces pain and swelling but they don’t fit in with your style. Until now,’ the website reads, reminding us that it’s actually very fun and chic to wear compression socks, no matter your age.

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Did You Make Your Connecting Flight? You May Have A.I. to Thank.

Airlines are using artificial intelligence to save fuel, keep customers informed and hold connecting flights for delayed passengers. Here’s what to expect.

A map of the contiguous United States marked with airline routes between hubs like Miami, Boston, New York and Los Angeles, with red, orange, green, blue, red and purple areas that look like storm systems on a radar map. A hand is holding up a cellphone that shows the seating chart of a plane. A message on the screen reads, “JFK-LAX: Holding for Delayed Passengers. On-Time Arrival Projected” and “Gate 10, Seat 5A.”

By Julie Weed

Last month in Chicago, a United Airlines flight to London was ready to depart, but it was still waiting for 13 passengers connecting from Costa Rica. The airline projected they’d miss the flight by seven minutes. Under normal circumstances, they’d all be scrambling to rebook.

But thanks to a new artificial-intelligence-powered tool called ConnectionSaver, the jet was able to wait for them — their checked bags, too — and still arrive in London on time. The system also sent text messages to the late-arriving passengers and the people on the waiting jet to explain what was happening.

A.I. still might not be able to find space for your carry-on, but it could help put an end to the 40-gate dash — sprinting to catch your connecting flight before the door slams shut — as well as other common travel headaches.

It’s not just United. Alaska Airlines , American Airlines and others have been working to develop new A.I. capabilities that could make flying easier for passengers. The carriers are also using the technology to reduce costs and streamline operations, including saving fuel, said Helane Becker, an airline industry analyst for the investment bank TD Cowen . Although many of the airlines are developing their programs independently, a successful innovation by any carrier could possibly become an industry standard.

A.I. is poised to change almost every aspect of the customer flying experience, from baggage tracking to personalized in-flight entertainment, said Jitender Mohan, who works with travel and hospitality clients at the technology consulting company WNS .

Saving fuel and frustration

A.I. has been helping Alaska Airlines dispatchers plan more efficient routes since 2021. “It’s like Google maps, but in the air,” explained Vikram Baskaran, vice president for information technology services at the carrier.

Two hours before a flight, the system reviews weather conditions, any airspace that will be closed, and all commercial and private flight plans registered with the Federal Aviation Administration, to suggest the most efficient route. The A.I. takes in “an amount of information no human brain could process,” said Pasha Saleh, the corporate development director and a pilot for Alaska.

In 2023, about 25 percent of Alaska flights used this system to shave a few minutes off flight times. Those efficiencies added up to about 41,000 minutes of flying time and half a million gallons of fuel saved, Mr. Baskaran said.

On the ground, American Airlines and others are working on an A.I.-powered system American calls Smart Gating — sending arriving aircraft to the nearest available gate with the shortest taxiing time, and if the scheduled arrival gate is in use, quickly determining the best alternate gate. All this could mean fewer frustrating minutes spent waiting on the tarmac.

American introduced Smart Gating at Dallas Fort Worth International Airport in 2021 and now employs it at six airports, including Chicago O’Hare and Miami International. The airline estimates it saves 17 hours a day in taxi time and 1.4 million gallons of jet fuel a year.

Mr. Mohan said that using A.I. as a virtual parking attendant could save up to 20 percent of taxiing time, with the highest benefits seen at the largest airports.

Faster and better customer service

Rapidly evolving generative A.I. — think ChatGPT — is helping airlines communicate with passengers better. At United, a companywide challenge last year yielded a plan to make texts sent to fliers more specific about what’s causing delays. Passengers can get frustrated when flights are delayed with no explanation, said Jason Birnbaum, United’s chief information officer.

But tracking the details required, composing an appropriate message and sending it to the right people for 5,000 flights a day would be too much for the staff to handle, Mr. Birnbaum said. Generative A.I. can process all that data and create messages tailored to conditions. For example, passengers booked on a January United flight from San Francisco to Tucson received this text message, along with a new departure time and an apology: “Your inbound aircraft is arriving late due to airport runway construction in San Francisco that limited the number of arrivals and departures for all airlines earlier.”

Having a more detailed explanation can calm travelers’ nerves. Jamie Larounis, a travel industry analyst who flies about 150,000 miles a year, recalled receiving text messages last summer explaining that a storm and a related crew-scheduling problem had delayed his flight from Chicago. “Getting a specific reason for the delay made me feel like the airline had things under control,” he said.

Generative A.I. is also good at summarizing text, making it a powerful tool for wading through emails. Last year, Alaska was among the carriers that began using A.I. to handle customer messages more efficiently. The airline’s system “reads” each email and summarizes the issues raised.

“We used to read first in first out, handling the requests as they came in,” said Mr. Baskaran, but now the system helps prioritize emails. For example, an urgent request involving an upcoming flight may take precedence over a complaint about a past one.

The system also helps a human agent decide how to respond, such as offering the customer a voucher, and it may draft an initial written response. “The person makes the decision, but it’s streamlined,” Mr. Baskaran said.

For all the benefits A.I. promises to airlines and passengers, the technology still has some shortcomings. For one, it doesn’t always deliver accurate information. In 2022, an Air Canada chatbot incorrectly promised a traveler that if he booked a full-fare flight to a relative’s funeral, he could receive a bereavement fare after the fact. When he filed a small-claims case, Air Canada tried to argue that the bot was its own separate entity, “responsible for its own actions,” but a tribunal found Air Canada responsible and ordered it to pay about $800 in damages and fees.

Still, as A.I. develops and airlines race to find more uses for it, passengers could see even more benefits. “As a customer and a business person, this is one of the biggest technology disruptions in the last five to eight years,” Mr. Mohan said.

Follow New York Times Travel on Instagram and sign up for our weekly Travel Dispatch newsletter to get expert tips on traveling smarter and inspiration for your next vacation. Dreaming up a future getaway or just armchair traveling? Check out our 52 Places to Go in 2024 .

An earlier version of this article, in a quotation from Vikram Baskaran, vice president for information technology services at Alaska Airlines, misstated the number of gallons of fuel an artificial-intelligence-powered planning system saved the airline in 2023. It was half a million, not half a billion.

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Open Up Your World

Considering a trip, or just some armchair traveling here are some ideas..

52 Places: Why do we travel? For food, culture, adventure, natural beauty? Our 2024 list has all those elements, and more .

Mumbai: Spend 36 hours in this fast-changing Indian city by exploring ancient caves, catching a concert in a former textile mill and feasting on mangoes.

Kyoto: The Japanese city’s dry gardens offer spots for quiet contemplation in an increasingly overtouristed destination.

Iceland: The country markets itself as a destination to see the northern lights. But they can be elusive, as one writer recently found .

Texas: Canoeing the Rio Grande near Big Bend National Park can be magical. But as the river dries, it’s getting harder to find where a boat will actually float .

COMMENTS

What Is A Knot Speed Defined As In Aviation?
The definition of a knot. A knot is a speed measurement equivalent to one nautical mile per hour. In other words, if the aircraft is flying at a speed of 450 knots, it covers a distance of 450 nautical miles in one hour. One nautical mile is roughly equivalent to 1.151 statute (land-based) miles. That also means one knot roughly equals 1.151 mph.
Plane Speed: How Fast Do You Need To Fly?
Let's say you're flying a 300 hp, 1980 Bellanca Viking that actually does deliver its advertised 175 kt cruise speed. Its spec sheet says its range is barely 600 miles (and we'll bet that isn't at 175 knots. So, to safely make 1,200 miles and still have some reserve, it would have to stop twice to get gas.
Why Do Pilots Measure Airspeed In Knots?
Therefore, the use of knots provides a quick estimation of time and speed requirements for pilots . Additionally, it is noted that using knots is simpler as the numbers are within a smaller range when it comes to the speed of commercial aircraft - between 0kt and 400kt. Airplanes travel greater distances and are affected by the curvature of the ...
How Fast Do Commercial Planes Fly?
Single-engine airplanes, such as the Cessna 172, fly considerably slower than commercial airplanes. For the typical single-engine plane, you'll be able to fly around 140 mph (122 knots). However ...
How fast does an airplane really go?
Second, different aircraft types are capable of traveling at different speeds. How fast is an airplane in the air? Airspeed is measured in knots. One knot equals 1 nautical mile per hour. One nautical mile is 1.15078 statute miles (what we commonly know as a mile). So, 1 knot is equal to 1.15078 miles per hour.
How Fast Do Passenger Planes Fly?
Passenger planes have different cruising speeds, with an average range of 500-521 knots (575-600 mph). The Concorde was the fastest-ever commercial passenger aircraft, reaching speeds of 1,350 mph (Mach 2). Air travel remains the safest and fastest mode of commercial passenger and cargo transport, making it the preferred choice for over four ...
Why Do Airlines Use Knots Instead Of Miles Per Hour?
A: This goes back almost to the dawn of flying and is connected to the nautical roots that many airlines have. A nautical mile is equal to one minute of latitude or 6,076 feet vs a statute mile at 5,280 feet. When your navigating using charts, the use of nautical miles because of its relationship to latitude makes navigation a lot easier.
KTAS
When traveling by plane, the speed at which you measure is a bit different, pilots use Knots True Airspeed (KTAS). What is a Knot? Also known as a nautical mile, knots are measurements that planes and ships use to measure speed. One Knot per hour equals 1.15 miles per hour.
KIAS in Aviation
A knot is a nautical mile per hour. Distances are measured in aviation using nautical miles (NM), which are equal to the distance between one minute of latitude. The unit is standard for navigational purposes and used the world over, whether traveling by air or sea. It is the standard measurement on all charts that use latitude and longitude.
Flying High: A Guide to Understanding Commercial Plane Speeds
Commercial plane speeds are measured in knots, a unit of speed equivalent to one nautical mile per hour. One nautical mile is equivalent to 1.15 miles on land. Planes typically travel at speeds of between 400 and 700 knots, depending on their type and the conditions they are flying in.
Principles Of Flight
Lift is proportional to the square of the aircraft's velocity, meaning that an airplane traveling at 200 knots has four times the lift as the same airplane traveling at 100 knots if the AOA and other factors remain constant; All other factors being constant, for every AOA, there is a corresponding airspeed required to maintain altitude in ...
Why is Airspeed Measured In Knots?
Knots Indicated Airspeed: This is the airspeed (in knots) directly calculated from the air pressure inside the pitot probe of aircraft and it represents the speed of airflow as the aircraft travels through the air. Knots Calibrated Airspeed: By correcting for the minor instrumental and positional errors of the pitot probe we get the Knots ...
Why transatlantic aircraft are flying at the 'speed of sound'
This plane reached a top speed of 777 mph or 675 knots. Courtesy Flightradar24 American Airlines flight 106 from JFK to Heathrow arrived 54 minutes early on Wednesday morning, with a flight time ...
Jet Speeds Uncovered: How Fast Do Commercial Airplanes Fly?
Approaching the airport means slowing down as much as possible while maintaining control of the aircraft. Most planes are shooting approaches at 150 knots or less. This requires using wing flaps and other high-lift devices to maintain control. Supersonic Air Travel. So how fast do commercial planes fly if they're going at supersonic speeds?
How Fast Do Commercial Planes Fly? Everything You ...
You can calculate it using this formula: Ground speed = knots + windspeed. Up at cruising altitude, high-level winds can be particularly strong. It's not uncommon for 100 mph (ca. 161 km/h)+ winds. Aircraft route planners and airline pilots, seek these winds — known as jet steams — to help push the aircraft towards their destination.
How Fast Do Planes Land? (By Aircraft Type)
An airliner will typically begin its descent at a cruising altitude of 30,000 feet at 3,000 feet per minute. As it reaches 10,000 feet and below, a speed restriction of 250 knots is enforced, reducing the descent to a speed of approximately 1,500 feet per minute. When 10-15 miles from the destination, the airliner will slow to landing speed.
KTAS: Knots True Airspeed and What It Means
The knots true airspeed tells pilots how fast the plane is going in relation to the air around it. The speed changes based on air pressure, temperature, and weather. Pilots use knots true airspeed to calculate flight plans, fuel costs and needs, and navigation. In the private plane industry, it's a factor in calculating flight price.
Knot (unit)
The knot (/ n ɒ t /) is a unit of speed equal to one nautical mile per hour, exactly 1.852 km/h (approximately 1.151 mph or 0.514 m/s). The ISO standard symbol for the knot is kn. The same symbol is preferred by the Institute of Electrical and Electronics Engineers (), while kt is also common, especially in aviation, where it is the form recommended by the International Civil Aviation ...
How Fast Do Commercial Aeroplanes Fly?
A typical commercial passenger jet flies at a speed of about 400 - 500 knots which is around 460 - 575 mph when cruising at about 36,000ft. This is about Mach 0.75 - 0.85 or in other words, about 75-85% of the speed of sound. Generally speaking, the higher the aircraft flies, the faster it can travel.
True Airspeed Calculator
The second true airspeed formula used makes this a true airspeed to the ground speed calculator: GS = TAS + W * cos θ. where: GS - Ground speed; W - Wind speed; and. θ - Angle between the wind direction and aircraft's motion. The third method uses the values of altimeter setting, altitude, and calibrated airspeed (CAS) or indicated airspeed ...
Looking For 200 Knots
Two hundred knots has become the new improbable dream that 200 mph used to be. Range, payload, climb, endurance and all the other parameters shrink to relative insignificance compared to pure, unbridled speed. Advertisement. That's not to demean 200 mph (or if you'd rather, the less numerically significant 174 knots).
How Windy Does It Have to Be Before Planes Can't Take Off?
Accordingly, the maximum acceptable crosswind component is 25 knots. "These calculations are performed on the airplane in our flight management system," a commercial pilot for a US carrier told TPG in an email. "We have limitations on the aircraft that can't be exceeded. For instance, we have a limitation on my airplane that our maximum takeoff ...
Why Do Boats & Planes Use Knots? You Won't Leave Confused!
The same goes for the kilometer. Traveling 20 kmh means you will travel 20 kilometers in one hour, if you are going 20 kmh. Nautical miles, on the other hand, is still based on the per hour system, but is calculated in knots. Traveling one nautical mile means that your speed is one "knot" per hour. As time continues to go on.
How Fast A Plane Do You Need?
If your prime travel distance is, for the sake of choosing a round number, 500 nautical miles, then one could make a compelling argument that you don't need a 175-knot cruiser to make that trip reliably and regularly. ... For a trip of 1,000 miles, a 700-nm-range, 175-knot plane looks great. Adding in that fuel stop on a long mission is a ...
Flight Time Calculator
Flying time between cities. Travelmath provides an online flight time calculator for all types of travel routes. You can enter airports, cities, states, countries, or zip codes to find the flying time between any two points. The database uses the great circle distance and the average airspeed of a commercial airliner to figure out how long a ...
Convert Knots to Miles per Hour
Something traveling at one knot is going about 1.151 land miles per hour. Common abbreviations: kn, kt. Miles per Hour. A mile per hour is a unit of speed commonly used in the United States. It is equal to exactly 1.609344 kilometers per hour. Common abbreviations: mph, mi/h. Knots to Miles per Hour Conversion Table.
Time from Speed and Distance
Calculate the time in hours by dividing the nautical miles by the knots; 4325 ÷ 45 = 96.1. It will take 96.1 hours to travel the 4325 nautical miles at a speed of 45 knots. 96 hr - 6 min - 40 sec.
Beriev Be-2500: What Should You Know About The Proposed Super ...
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Principles of Flight

Introduction:

Bernoulli's Principle:

Newton's Laws of Motion:

Newton's second law:

Newton's Third Law:

Lift as an Equation:

Coefficient of Lift:

Air Density:

Controlling Lift:

Angle of Attack:

Velocity/Airspeed:

Lift/Drag Ratio:

Airfoil Design:

Airfoil Construction:

Chord Line:

High Pressure Below:

Low Pressure Above:

Pressure Distribution:

Airfoil Behavior:

Wingtip Vortices & Lift:

Measuring Thrust:

Thrust During Acceleration: