av8a
Assumed Temperature Thrust Reduction.
A way of reducing T/O thrust to acceptable limits, within Perf A, by taking your TOW and calculating the maximum temperature that you could T/O at that weight using full T/O thrust.
A natural product of the above is, given the actual temp at T/O, is how much thrust is actually needed to T/O off at this weight.
The result is a reduced T/O thrust for a given weight and temp (and wind of course) that was calculated using the ASSUMED max temp.
A simplistic explanation but I hope it helps.