August 22, 2019 by Leonardo Brum Fornasier in Studying

What are the Take-Off Speed Definitions?

The best way for a pilot start a day is being on the runway ready to Take-Off but before we apply the Take-Off thrust let´s study today the Take-Off Speed Definitions to be ready to answer any question from your Flight Instructor.

What is Critical Speed?

Critical Speed is the lowest speed possible for a Multi-Engine Aircraft which the pilot with constant power can maintain heading after an engine failure.

What is Velocity Minimum Control Ground (VMCG)?

Velocity Minimum Control Ground (VMCG) is the speed at the pilot can maintain directional control of the aircraft around the normal vertical axis using the rudder control to keep runway heading.

What is Decision Speed (V1)?

Decision Speed (V1) is the speed at is possible to the pilot abort the Take-off and stop the aircraft until the end of the ASDA or continue the take-off in the case of engine failure and achieve
the Screen Height at the end of TODA.

The range of the Decision Speed (V1), needs to be higher or equal than VMCG and less or equal than VMBE (Velocity Maximum Brake Energy).


How does Aircraft Weight affect V1?

When the field length is limiting, with greater weight, lower is the V1 to assure sufficient stop distance available to stop the aircraft in case an aborted take-off. If the field is not limiting, with greater weight, higher is the V1 speed.

What is wet V1?

Wet V1 is a reduced normal V1, this speed is used to improve the stop distance available in case of an aborted take-off on a wet or slippery runway but it can´t be used as a normal V1 because it degrades the aircraft chances to the aircraft reaches Screen Height at the final of TODA in case of an engine lost.

What is Velocity Maximum Brake Energy (VMBE)?

Velocity Maximum Brake Energy (VMBE) is the speed at the aircraft can reject a take-off and remain within the heat limitations of the brake system.

What is Velocity Minimum Unstick (VMU)?

Velocity Minimum Unstick (VMU) is the lowest tested speed which it is possible to the aircraft get airborne with all engines without any hazard.

What is Velocity Minimum Control Air (VMCA)?

Velocity Minimum Control Air (VMCA) is the lowest speed possible for a multi-engine aircraft, in case of an engine failure to maintain heading and five degrees bank towards the good engine.

What is Stall Speed (Vs)?

Stall Speed (Vs) is the minimum speed which is the aircraft is controllable. Aircraft weight and configuration can change the Stall Speed.

What is Rotation Speed (VR)?

Rotation Speed (VR) is the speed where the pilot initiates the rotation to get airborne to reach Screen Height at the end of the Take-off Distance Available.

VR will never be less than:

1.05 * VMCA

1.1 or 1.05 VMCU

VR will never be less than V1

VR > = V1

What is Take-Off Safety Speed (V2)?

Take Off Safety Speed (V2) is the speed achieved at the Screen Height which is possible for a multi-engine aircraft climb and maintains directional control in case of an engine lost.

V2 will never be less than:

Vs * 1.2

VMCA * 1.1

Have Safe Flights!

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