Hi,
First of all, the performance calculated are catered for OEI. Therfore, if you are allowed" to takeoff by the software, therotically, it is safe to continue on CLB thrust.
However, at the extreme end of the performance, we definitely wants to get away from ground as soon as possible.
Here's what I used to do on the 777,
- Engine Fire at 400ft AGL ....
- Engaged AP if allowed !!
- Carried out the drill ! Once we retard the thrust lever on fire, we TOGA the other one immediately if we feel that additional power is needed. (It takes less than 2 sec to push the TOGA button while the PM is reading the next step of the EICAS.)
-accerlaration comes in ONLY we have secured the engine( that is put out the fire and we have a 10min allowance on TOGA power in case of OEI.
Noise abatment and all other regular ATC requirements are thrown out of the window once you have an emergency.
By exercising good airmenship, should the need of TOGA power be needed, just use it. We can't put a blanket on this, for example, a very light 772Er might have VMCA issue. Further more, since you are on very heavy weight T/O, your thrust might be very close to TOGA power as well.
Just my 2 cents worth, haven't flown the 777 for a year or so, do correct me if I am wrong.
Cheers,
lion-g