Here's a scenario - We are departing off a contaminated runway where the contaminant is standing water and it's reported on the ATIS as a wet runway, there's been windshear reports (PIREPS) and the winds are gusting, say 15G25 or stronger.
What takes priority now in deciding what thrust setting is to be determined? The PIRPES or the runway status?
Well, if your take off performance doesn't allow you to take off with full thrust, that kind of settles it?
The scenario is a short, contaminated runway. With full thrust you will have a high VMCG. Hence, a high V1 and performance-wise it won't give you enough space to stop from the high V1.
With reduced thrust, your VMCG gets lower and subsequently the V1 can be lowered too, allowing more space to stop.
Combined with wind sheer it all get's a bit theoretical! Perhaps wait for the runway to be cleared?
