Autopilot engagement and disengagement
Stabilise first
Establish a controlled attitude, speed and climb or descent. Check that the intended lateral and vertical modes are active.
Engage
Press AP on the guidance panel when the conditions are suitable. FSS says engagement is inhibited on the ground and lists a 400 ft minimum engagement height. Check the applicable height reference and aircraft limitations.
Confirm on both PFDs
Look for the AP indication on the FMA and verify the aircraft follows the intended guidance.
Monitor the flight
Continue checking speed, thrust, path, altitude and mode transitions. The yaw damper is a separate function: FSS says it engages automatically after power-up of hydraulic system 1 or 3 and can also be engaged or disengaged with the YD button. Check its status when required for the approach.
Disconnect normally
FSS describes the control-wheel quick-disconnect button as the normal method. The first press disconnects and triggers indications; a second press acknowledges them. TCS is different: FSS says holding it temporarily overrides the AP, which resumes control when TCS is released.
Investigate an unexpected disconnect
FSS lists manual pitch-trim input, stick-shaker activation and windshear escape guidance among the disconnect conditions. Its vertical-modes page says the windshear mode is not simulated; check your installed version. For a non-normal disconnect, FSS says one press of a control-wheel AP disconnect button cancels the flashing AP indication and silences the warning. The AP page also describes a disconnect after sustained light or brief stronger opposing control input, but gives no measurable force or time threshold. Record the flight mode and hardware state before changing settings. [166] [38] [10]
FSS says the autopilot remains engaged after an engine failure. Check the AP indication and the aircraft response, then use the applicable non-normal procedure; do not assume the autopilot has disconnected. FSS FMA [167].
FSS says the yaw damper automatically disengages when both hydraulic systems 1 and 3 are shut down. The YD button can also engage or disengage it; confirm the indication after a change. [168]