INTERMEDIATE FLIGHT PREPARATION WORKBOOK
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. VR is compared with VMCG
and VROT in determining S1.
Maximum Braking Speed
Maximum Braking Speed (VB) is the maximum speed from which the aircraft can be brought to a
stop without exceeding the maximum brake energy limit (14.8 million ft-lbs total). When setting
up the Takeoff Acceleration Check, care should be taken to choose the checkpoint such that the
resulting speed is below VB.
Takeoff Acceleration Check
A Takeoff Acceleration Check provides a speed for a given distance during takeoff ground roll.
This speed can be checked against aircraft IAS at that distance point to ensure the takeoff is
proceeding normally. Takeoff Acceleration Check speed should be adjusted to be at least 10
KIAS less than S1. Compute Takeoff Acceleration Check whenever S1 is less than VROT.
The takeoff is committed at IASs above Go/No-Go Speed (S1). If an engine failure occurs prior
to obtaining S1, takeoff abort capability is assured. In takeoff planning, S1 is equal to or greater
than the higher of VMCG or VCEF. However S1 must not be higher than the lowest of VR, VROT, or
VB. If it is higher, the takeoff weight must be reduced until this requirement is met.
Rotation Speed (VROT) 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 VMCG.
Lift-off is the moment at which the main gear lifts off the runway.
Lift-Off Speed (VLOF) is the speed at which lift-off occurs.
Takeoff flare is the ground distance covered between lift-off and the 50-foot obstacle height.