The majority of the following terms are used in this instructor guide. Others may be encountered in flying various aeroplane types.
VA — Manoeuvring Speed - the maximum speed at which the application of full available aerodynamic control will not overstress the aeroplane.
VF — Design Flap Speed - the maximum speed at which wing flaps may be actuated.
VFE — Maximum Flap Extended Speed - the maximum speed permissible with the wing flaps in a prescribed extended position.
VLE — Maximum Landing Gear Extended Speed - the maximum speed permissible with the landing gear extended.
VLO — Maximum Landing Gear Operating Speed - the maximum speed permissible for the extension or retraction of the landing gear.
VMC — Minimum Control Speed - the minimum flight speed at which it is possible to retain control of the aeroplane and maintain straight flight, through the use of maximum rudder defection and not more than 5 degrees of bank, following sudden failure of the critical engine.
NOTE 1: VMC for an aeroplane type is generally determined under the following conditions:
- all engines developing maximum rated power at the time of critical engine failure
- the aeroplane at a minimum practical weight and with a rearmost centre of gravity; and
- landing gear retracted, flaps in take-off position and the propeller of the critical engine windmilling.
NOTE 2: 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.
Refer to AC 23-8B – Flight Test Guide for Certification of Part 23 Airplanes at the following website: http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/
VSO — Stalling Speed - the minimum steady flight speed at which the aeroplane is controllable in the landing configuration.
VSSE — Intentional One Engine Inoperative Speed - a speed above both VMC and the stall speed, selected to provide a margin of lateral and directional control when one engine is suddenly rendered inoperative. An intentional failing of one engine below this speed in not recommended.
VX — Best Angle-of-Climb Speed - the speed that provides the maximum altitude gain for the horizontal distance travelled.
VXSE — One Engine Inoperative Best Angle-of-Climb Speed - the speed that provides the maximum altitude gain for the horizontal distance travelled with one engine inoperative.
VY — Best Rate-of-Climb Speed -- the speed that provides the maximum foot-per-minute altitude gain.
VYSE — One Engine Inoperative Best Rate-of-Climb Speed - the speed that provides the maximum foot-per-minute altitude gain with one engine inoperative.
Accelerate/Stop Distance - distance required to accelerate the aeroplane to lift-off speed, and on experiencing an engine failure or emergency at that point, immediately discontinue the take-off, and stop the aeroplane on the remaining runway.
Accelerate Stop Distance Available (ASDA) - the length of the take-off run available plus the length of the stopway, if provided.
Critical Engine - the engine that, if inoperative, would most adversely affect the performance or handling qualities of an aeroplane.
Drift-Down Altitude - the altitude to which, following the failure of an engine above the one engine inoperative absolute ceiling, an aeroplane will descend to and maintain, while using maximum available power on the operating engine and maintaining the one engine inoperative best rate of climb speed.
Imminent Stall - thecondition in which an aeroplane exhibits symptoms of an approaching stall.
Landing Distance Available (LDA) - thelength of runway declared available and suitable for the ground run of an aeroplane landing.
One Engine Inoperative Absolute Ceiling - maximum density altitude that an aeroplane is capable of attaining, at gross weight, clean configuration while using maximum available power on the operating engine and maintaining the one engine inoperative best rate of climb speed.
One Engine Inoperative Service Ceiling - maximum density altitude at which an aeroplane is capable of climbing at 50 feet per minute, at gross weight, clean configuration, while using maximum available power on the operating engine and maintaining the one engine inoperative best rate of climb speed.
Pilot Operating Handbook (POH) - Manufacturer's operating manual for a particular make and model of aeroplane. POH is a generic term applying to publications that manufacturers have designated as containing operating information relevant to a particular aeroplane type.
Take-off Distance Available (TODA) -the length of the take-off run available plus the length of the clearway, if provided.
Take-off Run Available (TORA) - the length of runway declared available and suitable for the ground run of an aeroplane taking off.
Take-off Safety Briefing - the briefing in which, prior to take-off the pilot reviews his intentions regarding the procedure for take-off and departure, including plans for actions to be taken in the event of an emergency.
Zero-Fuel Weight - theweight of the aeroplane with passengers and baggage, but without usable fuel. All weight in excess of a published maximum zero fuel weight must be in the form of fuel.
Zero-Thrust Power Setting - manifold pressure and RPM setting used to simulate a failed engine with the propeller feathered.