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General - Definitions

  1. Critical engine - The engine that, upon failure, would most adversely affect the performance or handling qualities of an aeroplane.

  2. Design Flap Speed (VF) - the maximum speed at which wing flaps may be extended.

  3. Intentional One Engine Inoperative Speed (VSSE) - a speed above both (VMC) and stall speed, selected to provide a margin of lateral and directional control when one engine is suddenly rendered inoperative.  Intentional failing of one engine below this speed is not recommended.  In the event that the POH/AFM does not state a VSSE, use a speed equal to VMC +10 knots.

  4. Manoeuvring Speed (VA) - the maximum speed at which the application of full available aerodynamic control will not overstress the aeroplane.

  5. Maximum Flap Extended Speed (VFE) - the maximum speed permissible with the wing flaps in a prescribed extended position.

  6. Maximum Landing Gear Extended Speed (VLE) - the maximum speed permissible with the landing gear extended.

  7. Maximum Landing Gear Operating Speed (VLO) – the maximum speed permissible for operating the landing gear.

  8. Minimum Control Speed (VMC) - the minimum flight speed at which it is possible to retain control of the aeroplane and maintain straight flight, with maximum rudder deflection and not more than 5 degrees of bank, following sudden failure of the critical engine.

    NOTE: (VMC) for an aeroplane type is generally determined under the following conditions:

    1. all engines developing maximum rated power at the time of critical engine failure;

    2. the aeroplane is at a minimum practical test weight with a rearmost centre of gravity;

    3. landing gear retracted, flaps in take-off position and the propeller of the failed critical engine windmilling.

    At speeds below (VMC), the aeroplane will yaw and roll towards the failed engine.  It cannot be too strongly emphasized that control will be regained only by a reduction in power of the good engine or by increasing airspeed through a change in pitch attitude, or both.

  9. One Engine Inoperative Best Angle-of-Climb Speed (VXSE) - the speed that provides the maximum altitude gain for the horizontal distance travelled with one engine inoperative.

  10. One Engine Inoperative Best Rate-of-Climb Speed (VYSE) - the speed that provides the maximum altitude gain per minute with one engine inoperative.

  11. Stalling Speed (VSO) - the minimum steady flight speed at which the aeroplane is controllable in the landing configuration.
Date modified:
2010-05-20