Thank you guys for all the answers.
Here is the scenario:
The following data is set into the FMS:
Acceleration height : 3,000
Thrust reduction height: 800
E/O acceleration height: 1,500
D-TO-2 (the highest Derate available)
FMS recommends CLB-2 but we take CLB-1 (it saves fuel since you reach cruising alt. faster). Lufthansa once checked it and came up with that conclusion. We just follow them on that.
Assumed temp. : 50 degrees
Plane is light (~250 tons)
I don't have the numbers for D-TO-2 power or CLB-1 power but this scenario happens often and N1 (or EPR) for CLB-1 is higher than D-TO-2 power.
Performing a VNAV takeoff.
Rotating at Vr
climbing at V2+10
While crossing height 800' VNAV changes from D-TO-2 power to CLB-1 power and increases thrust (thus creating a new and higher Vmca).
So far so good since we didn't loose any engine yet.
But Murphy (or the sim TRI) now takes one engine (or 2 on the same side if he didn't drink his coffee that morning).
Now what?
Did someone check wether in that scenario the new Vmca is still higher than V2 (+10)?
And what if we now encounter a windshear and need more power, or let's take a more probable scenario - our E/O recovery wasn't perfect and we didn't meet the planned performance calculation and now our new flight path is lower than the calculated one, and we also deviated 10 degrees off course, and up ahead there are some obstacles or terrain, and the next thing we hear is the GPWS going off and we must add power. Now what?
Ok I know I got carried out with my second scenario with the GPWS but the First scenario with the higher CLB power definately happens on a daily or weekly basis.
Does the performance calculations take that scenario into consideration?
* also, in the meanwhile, I asked around and found out that Lufthansa used to take these scenarios into consideration back in the days before EFB was available and they used to check for every debated takeoff the Vmca for full thrust for that takeoff, and they used to write it on the takeoff card, and in that case they had an available reference in case they HAD to add power.
But nowadays when we use EFB that is no longer possible since the OPT (the performance calculations app) does not provide any data for Vmca...