In retrospect, after posting, I was afraid that the 'other' considerations of a second press of the TOGA switches was going to raise it's head. I was thinking of the airborne engine failure case (comes from doing too much work on engine failure after Takeoff cases), rather than the 'On the grounf all engines operating case'. I should have read the original post more carefully
To qualify my 'second press of TOGA' remarks, the first is the application of Takeoff thrust at the commencement of Takeoff, the second is the next one. There is a significant difference between the on ground and in flight cases.
Wizofoz, you are absolutely correct in stating "
On the take-off roll, above 80kts, all that does is disarm LNAV and VNAV- you need to advance the thrust levers manually to get any more grunt. Yes, full Thrust lever position ONLY will give you FULL Un-Derated Takeoff thrust.
King on a Wing, with respect, for the in flight case, you're incorrect, but I wish that you were correct!
.1. On the ground, pushing the Thrust Levers to the fire-wall will give you Maximum Takeoff Thrust, and
.2. In flight, following engine failure, pressing the TOGA switches OR pushing the Thrust Levers to the fire-wall will give you Maximum Takeoff Thrust. Pressing the TOGA switches removes the derates, and this is where I wish you were correct...... more on this -
V1, Vr and V2 are based upon Vmcg and Vmca for the Derated Thrust. The problem arises after engine failure that if, for example the V speeds were based upon TO-2 (20% De-Rate), full Takeoff thrust might put you into a severe and unrecoverable directional control situation, yet, some people will do it. I wish you were correct in stating that pressing TOGA 'only' removed the Assumed Temp and gave you full De-Rated thrust, that could be highly desirable, but it is not so, you get the full works. The only way to obtain the De-Rated thrust is to obtain the value from the FMC, and manually push the Thrust Levers to that value.
In our company we were concerned that on short flights where TO-2 was used with a large Assumed Temperature, pilots might press TOGA to obtain Full Thrust, and lose control. Our solution, as imperfect as it may be, was to determine the minimum weight at which the V Speeds provided VMC protection, and to NOT advance to TOGA following engine failure below those weights. (It's a low weight Takeoff problem).
NO, I'm not going to quote the weights as there are numerous varients out there, so look up the numbers for your own Aircraft / Engine combination.
Next time, I promise to thoroughly read the OP's text fully, as I've started an inadvertant thread drift. Sorry about that.
Regards,
Old Smokey