Interesting comments, for the B737's that I'm familiar with the envelope went to ISA +39.4C. In this part of the world, ISA+35 isnt sufficient, we just had the E170 recertified to ISA+39! IF his analysis stops at 50C, it sounds like an input limitation rather than a program limitation.
In this case the FMC speeds become invalid, and the Airport Analysis speeds must be used (FMC and QRH usually stop at the environmental limit).
We dont carry V-speeds nor are they published on the analysis, the FMC provides them right up to the maximum thrust reduction temperature which is generally about the environmental envelope.
Am I correct in saying that in this case I can use the QRH speeds for the actual weight of 42 tonnes - based on the advice provided in the QRH? After all, V speeds are based on actual weight - not a fictitious weight for convenience.
I would say that the answer is YES, you are correct. Using the FMC and runway analyis, we check for the highest assumed temperature and limiting weight. This temperature is entered into the FMC with the ACTUAL weight, V-speeds are for the actual weight and not the limiting weight (unless of course they are equal.)
Mutt