Capn. B
Asiana 214 is hardly an appropriate case to respond to my question.
“If you are aware of a circumstance where an A/T will not/has not woken up, having followed FCOM procedure and approved SOP’s, please enlighten us.”
(following in itallics, extracts from NTSB AAR 14/01 with my bolding and underlining).
You stated;
“You are defending the Boeing design feature that allows the ATS to stay asleep as the aircraft stalls.”
The aircraft did not stall, but anyway;
Note: When the pitch mode is FLCH or TOGA, or the airplane is below 400 feet above the airport on takeoff, or below 100 feet radio altitude on approach, the autothrottle will not automatically activate.
They were in FLCH and below 100 feet. The auto thrust behaved as advised.
The same student stated that another instructor had provided similar information during another 777 ground school class attended by the PF and advised students that they should not use FLCH to descend after crossing the FAF.
Refer to the underlined part of my question.
Having failed to follow SOP, the bigger question is “why did the crew not intervene to avoid”?
The flight crew's difficulty in managing the airplane's descent continued as the approach continued. In an attempt to increase the airplane's descent rate and capture the desired glidepath, the pilot flying (PF) selected an autopilot (A/P) mode (flight level change speed [FLCH SPD]) that instead resulted in the autoflight system initiating a climb because the airplane was below the selected altitude. The PF disconnected the A/P and moved the thrust levers to idle, which caused the autothrottle (A/T) to change to the HOLD mode, a mode in which the A/T does not control airspeed. {But the elevators do} The PF then pitched the airplane down and increased the descent rate. Neither the PF, the pilot monitoring (PM), nor the observer noted the change in A/T mode to HOLD.
Mode awareness anyone!
The FLCH SPD pitch mode is used to change flight level, and, just as with the V/S mode, the pilot may use this mode to climb or descend to the altitude set in the MCP. However, in this mode, the elevator commands from the AFDS maintain the MCP target speed, while the climb or descent rate (vertical speed) is controlled by an increase or decrease in thrust through A/T control or manual pilot control.
The flight crew did not consistently adhere to Asiana's SOPs involving selections and callouts pertaining to the autoflight system's mode control panel. This lack of adherence is likely the reason that the PF did not call out "flight level change" when he selected FLCH SPD. As a result, and because the PM's attention was likely on changing the flap setting at that time, the PM did not notice that FLCH SPD was engaged.
During the accident flight, after the A/P was disconnected, the PM loosely followed Asiana's informal practice, which was to turn both flight directors (F/Ds) off and then turn the PM's F/D back on when conducting a visual approach. However, the two F/D switches were not both in the off position at the same time. If they had been, the A/T mode would have changed to speed mode and maintained the approach speed of 137 knots. In addition, during a visual approach, F/D pitch and roll guidance is not needed and can be a distraction.
The PF's faulty mental model of the airplane's automation logic led to his inadvertent deactivation of automatic airspeed control.
More manual flight for Asiana pilots. Asiana's automation policy emphasized the full use of all automation and did not encourage manual flight during line operations. . If the PF had been provided with more opportunity to manually fly the 777 during training, he would most likely have better used pitch trim, recognized that the airspeed was decaying, and taken the appropriate corrective action of adding power.
The National Transportation Safety Board (NTSB) determined that the probable cause of this accident was the flight crew's mismanagement of the airplane's descent during the visual approach, the PF's unintended deactivation of automatic airspeed control, the flight crew's inadequate monitoring of airspeed, and the flight crew's delayed execution of a go-around after they became aware that the airplane was below acceptable glidepath and airspeed tolerances. Contributing to the accident were (1) the complexities of the autothrottle and autopilot flight director systems that were inadequately described in Boeing's documentation and Asiana's pilot training, which increased the likelihood of mode error;……….
Three factors any of which, would probably have averted the incident viz. Inappropriate mode selection, unstable approach procedure, and proper recycling of the F/D switches.
None of these were in Boeings control.
The aeroplane didn’t do anything that wasn’t documented, or should be unexpected.
I reiterate my previous statement:
if you want to venture into test pilot territory, be aware of the risks, and it’s all on your head when it bites you.
In the meantime;
“
If you are aware of a circumstance where an A/T will not/has not woken up, having followed FCOM procedure and approved SOP’s, please enlighten us."
Maui