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FutureStarrBoeing Take Off Speed
A plane's take off speed is determined by several factors, including its weight, weather conditions, runway length and more.
Under standard conditions, a Boeing 747 requires a ground speed of 296kph (184 mph) in order to take off. A headwind may decrease this requirement for speed.
V1 is the speed required for takeoff that pilots must reach in order to safely reject or abort it if an engine failure occurs. This speed is calculated before each flight using performance figures determined by the airplane manufacturer and tested during flight testing.
This formula accounts for runway length, obstacles, temperature, slope, weight and any other variables that could impact takeoff performance. Despite these variables, this single speed guarantees pilots will reach their required screen height (35ft dry and 15ft wet for FAR 25 aircraft) within the remaining take-off distance even if an engine fails.
Pilots can safely stop on the runway if their aircraft experiences any major issue before reaching V1 as long as they apply the necessary means to bring it to a safe halt. It also serves as an important speed for performing RTO maneuvers.
Pilots used to be taught that V1 was the "decision speed." This meant they could accelerate until they reached that speed and then make their decision whether or not to continue with takeoff. Unfortunately, this approach had its drawbacks; pilots couldn't always tell whether they had reached the required speed or rejected it altogether.
The new approach was to teach pilots to consider other conditions that could cause rejections, such as noncritical alerts, tire failures or systems issues that did not directly threaten safety during takeoff. This made RTO more realistic.
Take for instance the scenario: you were ready for takeoff when an engine failure occurred at 50 knots. Thanks to its low speed, however, you were still able to cover a short distance before reaching V1 and initiating the reject take-off maneuver.
Accelerate-Stop Distance (ASC) is the distance between two points that must be covered to complete an RTO. Therefore, it's essential that you calculate this value accurately.
One of the most intimidating parts of flying for many pilots is the potential engine failure during takeoff. Thankfully, engineers and manufacturers have done extensive calculations to guarantee that passengers remain secure even if something does go awry.
If you've ever waited on an airplane for takeoff, chances are you heard the pilot speaking about V1 and V2. This is usually just a way of reminding the flight crew that they need to accelerate and begin taking off.
Before taking off, there are a few things you should understand about these two speeds and what they signify. Most importantly, both are essential for successful take off.
Before a flight takes off, two speeds are calculated that are unique to each aircraft. They take into account factors like runway length, temperature, obstacles, slope, weight and more when making these calculations.
Pilots must reach V1 during takeoff to enable the plane to lift off and begin its flight. Additionally, they need to reach V2 so that their aircraft can climb safely without engine failure.
Once a pilot reaches V1, they should move their hand away from the throttle in case they need to abort the flight. After that, they are ready to begin moving their hand back towards the throttle in order to restart the plane if required.
Another important point to remember is that if a pilot reaches V2 after an engine failure, they must continue climbing until they reach an acceleration altitude. This allows them to stay in the air until their engines can be recovered.
A flight director can be invaluable in such instances, providing pilots with guidance on what to do when their engines malfunction. They'll have an angle of attack bar which indicates what pitch attitude is optimal for the plane in such cases.
Take off speed is one of the most critical elements in an aircraft flight, as it determines available margin for maneuvering during critical moments in flight and allows pilots to make informed GO/NOGO decisions. To guarantee a thorough briefing for take off, including all slat and flap configurations, weight, and take off speeds (especially those changed during taxi as per SOP), all relevant information should always be shared.
V3 refers to a single takeoff speed, known as the "decision speed" or "balanced field V1", that is determined by TODN-1 and ASDN-1 and depends on how far an aircraft covers with one engine disabled.
For takeoff to be successful, the TODN-1 must equal or surpass ASDN-1. This is because if a failure occurs late in the takeoff, more time must pass before both engines can accelerate together - meaning more kinetic energy is gained before impact, making stopping distance longer; thus requiring pilot to reduce engine thrust at precisely the right time.
Another consideration is the maximum speed at which brakes can absorb the most brake energy. This limit speed is defined during Airbus flight tests as "maximum brake energy speed" or "VMBE".
Crew must understand this speed, since that is when they must decide to accept take off or reject it before the aircraft reaches V1! If they fail to make this decision, the aircraft could run off the runway; alternatively, if rejected after reaching V1, it could remain airborne with burning brakes.
Crews should also be mindful of two additional take off speeds - V2 and Vr (V rotate) - which aren't mandated by regulations but must still be taken into account during flight preparation.
Have you ever sat on the plane, waiting to take off, and considered what might happen if your engine failed as you started accelerating? Well, Boeing engineers and pilots have done extensive calculations and come up with a series of safe speeds designed to help avoid this possibility.
The initial speed is V1, which is the maximum speed at which a rejected take-off can be initiated in an emergency. This ensures you can abort safely within the remaining runway if an engine malfunctions.
Speed can vary depending on a variety of factors, including aircraft type, wing flap settings, weather conditions and more. On average though, most commercial airliners have a V1 of around 140 knots; larger aircraft have higher V1s of about 150 knots to account for additional weight carried.
Another speed that should be considered during takeoff is V2 (also known as the safe take off speed). This speed is used during the second segment of take-off, when one engine has failed and another begins to take off. It is entered by the crew during flight preparation and represented by a magenta triangle on the PFD speed scale (fig.2).
V2 has more thrust than VMCA, which helps control the aircraft during flight and promotes safe takeoff. Furthermore, it eliminates ground effect and allows you to escape if an engine fails during take off roll.
V2 can be so safe that it may even be reduced below VMCA for certain flights and take-offs - especially wet runways. But doing this increases your ASDN-1, so be mindful of how it may impact flight performance.
You can reduce V1 in order to lower your ASDN-1 if you are accelerating with two engines and are able to gain kinetic energy before the critical engine fails on takeoff. In this case, you will have more runway distance to slow down or stop the airplane.