TOLD Definitions Flashcards
Critical Engine Failure Speed
(Vcef)
Critical engine failure speed is defined as the speed at which one engine can fail and the same distance is required to either continue to lift-off speed, or to abort and decelerate to a full stop.
Critical Field Length
(CFL)
The critical field length is the total length of runway required to accelerate on all engines to critical engine failure speed, experience an engine failure, then continue to lift-off or stop. It is used during take-off planning together with the climbout data to determine maximum gross weight for a safe takeoff and climbout. For a safe takeoff, the critical field length must be no greater than the runway available.
Minimum Control Speed Ground
(Vmcg)
Ground minimum control speed, Vmcg (88 KIAS), is the minimum controllable speed during the take-off run, at which, when an engine is failed, it is possible to maintain directional control using only primary aerodynamic controls without deviating more than 25 feet laterally with all three wheels on the runway. The speed is established with the remaining engine at the take-off thrust setting, the aircraft loaded at the most unfavorable weight and center of gravity and the aircraft trimmed for takeoff, without exceeding 180 pounds of rudder control force by the pilot with the rudder boost system operating. Conditions of crosswind and RCR may increase Vmcg.
Minimum Control Speed Air
(Vmca)
Air minimum control speed, Vmca (89 KIAS), is the minimum controllable speed in the take-off configuration out of ground effect with one engine inoperative and the remaining engine at take-off rated thrust. Vmca is determined at the most critical combination of asymmetric thrust, light weight, and aft center of gravity. The speed is established with the aircraft trimmed for takeoff, 5 degrees angle of bank into the operating engine and no more than 180 pounds of rudder control force by the pilot with the rudder boost system operating. Vmca is always less than take-off speed and is not considered in take-off planning.
Refusal Speed
(Vr)
Refusal speed, Vr, is the maximum speed that can be attained, with normal acceleration, from which a stop may be completed within the available runway length. Refusal speed is compared with ground minimum control speed and rotation speed in determining S1.
Maximum Braking Speed
(Vb)
Maximum braking speed, is the maximum speed from which the aircraft can be brought to a stop without exceeding the maximum brake energy limit (14.8 Million Foot-Pounds Total). When setting up the take-off acceleration check, care should be taken to choose the checkpoint such that the resulting speed is below Vb.
Go/No-Go Speed
(S1)
The takeoff is committed at indicated airspeeds at or above S1. If an engine failure occurs prior to obtaining S1 and action is taken to stop the aircraft before obtaining S1 , take-off abort capability is assured. In take-off planning, S1 is equal to or greater than the higher of ground minimum control speed or critical engine failure speed. However, S1 must not be higher than the lowest of refusal speed, rotation speed, or maximum braking speed. If it is higher, the take-off weight must be reduced until this requirement is met.
Rotation Speed
(Vrot)
Rotation speed is defined as the speed at which the aircraft attitude is increased from the ground run (taxi) attitude to the lift-off attitude. This speed is greater than the ground minimum control speed (Vmcg).
Reference Zero
The point in space at the end of the takeoff flare distance at which the aircraft reaches 50 feet above the runway elevation. Reference zero will occur no later than the departure end of the runway.
