Your point highlighted here was a design flaw & 'expression of it' in the functioning of the A/thr system. Regardless of how one reaches in HOLD-MODE, the point was the a/thr won't wake up in FLCH. And that is a dangerous situation because a pilot expects the A/THR to guard for speed.
Interestingly if you read the entire ASIANA 214 crash report (207 pages) following is CLOSE to what HOUBA is highlighting (BOEING received some flak as well) -
FINDINGS/CONCLUSIONS (apart from other factors)
Point 10. As a result of complexities in the 777 automatic flight control system and inadequacies in related training and documentation, the pilot flying had an inaccurate understanding of how the autopilot flight director system and autothrottle interacted to control airspeed, which led to his inadvertent deactivation of automatic airspeed control.
12. A review of the design of the 777 automatic flight control system, with special attention given to the issues identified in this accident investigation and the issues identified by the Federal Aviation Administration and European Aviation Safety Agency during the 787 certification program, could yield insights about how to improve the intuitiveness of the 777 and 787 flight crew interfaces as well as those incorporated into future designs.
RECOMMENDATIONS -
Require Boeing to revise its 777 Flight Crew Training Manual stall protection demonstration to include an explanation and demonstration of the circumstances in which the autothrottle does not provide low speed protection. (A-14-39)
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Infact many pilots were unaware prior to this incident 2013 that such a loophole exists in automation. To such a level where FCOMs & FCTMs lacked the exclusive info.
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Words by the author of the report -
Boeing issued a statement saying that it “respectfully disagrees with the NTSB's statement that the 777's auto-flight system contributed to this accident, a finding that [Boeing does] not believe is supported by the evidence.” Denial is the enemy of change. Such statements are perhaps issued by public relations personnel intent on protecting their brand.
However, this accident demonstrates that existing low airspeed alert systems that are designed to provide pilots with redundant aural and visual warning of an impending hazard due to low airspeed may not be adequately tailored to alert pilots to an impending hazard due to a combination of conditions (i.e., low airspeed combined with low altitude.
Yours was a great post HOUBA
just finished reading it.
