PhilosopherPilot
Well-Known Member
The issue with Boeing FLCH inside the FAF is that FLCH deactivates the autothrottle servos (THR HOLD). Unlike VNAV where the TLs will come back alive if you get slow, they won't do it in FLCH. As one poster mentioned, if you're hand flying, you need to be aware that the autothrottles would be providing no protection. Best to just turn everything off at that point and fly errplanes.
It's essentially the same for the E190. For a descent the thrust levers will either go to idle, or to a reduced power setting for shorter descents. They aren't technically deactivated, but they are fixed, and will not wake up no matter how slow you go, even if you get a shaker. In fact, that's one of the demos we do in the sim, a stick shaker with the AP off and AT on, with the pilot looking outside during a visual. The plane will happily let you stall in FLCH with the AT engaged.
We don't turn the ATs off, but we do not use FLCH on approaches for that reason. If the flight directors are off, the auto thrust mode becomes speed on thrust, so once you aren't using the flight directors anymore, they are mandated to be turned off. That provides an additional level of protection.
I have flown with handful of guys that click off the auto thrust when the AP is off, but that's fairly rare. Most, including myself, just keep a hand on the thrust levers and override it as necessary.