Just a quick question from a ‘Bus’ driver for you NG guys.
Can you put a fixed derate into the perf page of the MCDU?
If you can, then I would be surprised if you were able to achieve the normal max thrust by ‘firewalling’ the thrust lever. If you did firewall the donk with an engine failure on the runway above V1 when using T/O figures for a fixed derate, and did actually achieve the full thrust, then you would be in danger of losing control of the aircraft because it could well be below the VMCG for full thrust.