ian-380

Ah, ok! Makes more sense now. But you could also just increase the speed in the MCP right? haha. That and or selecting v/s seem like better options. Thank you very much guys.

Exactly! That's why i was confused with this mode. But don't FLCH and LVL CH control speed with pitch? If the IAS dropped, the aircraft would maintain idle thrust and pitch down, wouldn't it?

Oh ok. But why is this mode also engaged when the aircraft is descending in FLCH or LVL CHG mode? Couldn't the a/t just stay at IDLE, RETARD? Thank you very much for the response! Oh ok. But why is this mode also engaged when the aircraft is descending in FLCH or LVL CHG mode? Couldn't the a/t just stay at IDLE, RETARD? Sorry i'm posting it again, I forgot to choose "quote"

I can't understand a part of boeing's autothrottle system. Apparently the Asiana pilots couldn't as well, considering the 777 crash was caused by this misunderstanding. The problem lies in the 777's a/t HOLD mode, which is followed by IDLE mode. The 737 has the similar ARM, THR HLD, and RETARD modes. In these modes the servos are disconnected from the engines and the pilot can manually set thrust. Why? What is the purpose of disconnecting the servos? Thank you.