Deciding whether to reject a take-off at high speed is a very demanding situation accompanied by startle and surprise.
There are numerous possible reasons to consider a high speed RTO. The information available may be ambiguous, and the effect on stop margin uncertain.
This decision is time critical, irreversible, and it is virtually the only situation where it is impossible to get a second opinion.
Even if a second after quickly pulling back on the thrust lever, the realization sets in that the RTO was not the safest course of action, we are now commited to stop.
We train the drill, but we do not practice the decision making!
Virtually all simulator exercises have the goal to establish and check the RTO drill. We tell pilots to be go-minded, but in the sim, any irregularity during the take-off run inevitably requires a STOP decision – because that is what is required for the completion of the mission or check event.
If we train like this for years, a strong mental connection, almost a reflex, is established: When something unusual happens, do the drill and stop.
If you are unsure if this is an issue in your operation, try it out in the simulator. With no prior briefing, give a few crews a decision making challenge at 120 knots: a red EGT indication, a tire failure or an electrical bus failure, where some effects show. Record the rate of unwarranted RTOs.
“Many high speed rejected takeoffs (44%) should not have been conducted.“
NLR Air Transport Safety Institute, 2010
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