G/S beam capture at hard constraint at high OAT

[Hardy Heinlin]

Generally no; we want to follow FD commands.  If it's not doing what we want it to do, then the solution is to correct it with an appropriate mode such as V/S (unless it's obvious that manual flight is a safer option).  Disconnecting to ignore the FD would otherwise increase workload, as the PF will not only have to then fly manually, but should also direct the PM into the correct mode settings to refollow the FD.

The solution is to be aware of the ISA deviation and have a shallow descent segment perhaps a few nm long prior to the FAP where you'll be below the projected glideslope, so that a capture from below is assured.  That won't occur in VNAV; active intervention with another mode is required.

Thank you. So, when you're aware of the ISA deviation, you anticipate it indeed. But instead of ignoring the running VNAV guidance in manual flight, you will change to the V/S mode. That sounds more elegant, yes ...