此时,由于空速过低(三根皮托管测出的空速数据都小于60 kt),飞机认为这是电脑出了故障而抑制了失速警告,随后飞行员曾多次尝试推杆降低攻角,这使得空速回升,虽然还是失速但电脑认为这个值是有效的,再次触发了失速警告,这使得飞行员更加困惑;而如此重要的信息该片里竟然一句都没提。
调查报告原文:
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At around 2 h 11 min 42, the Captain re-entered the cockpit. During the following seconds, all of the recorded speeds became invalid and the stall warning stopped, after having sounded continuously for 54 seconds.
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At 2 h 12 min 02, the PF said, “I have no more displays”, and the PNF “we have no valid indications”. At that moment, the thrust levers were in the IDLE detent and the engines’ N1’s were at 55%. Around fifteen seconds later, the PF made pitch-down inputs. In the following moments, the angle of attack decreased, the speeds became valid again and the stall warning triggered again.
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If the CAS measurements for the three ADR are lower than 60 kt, the angle of attack values of the three ADR are invalid and the stall warning is then inoperative. This results from a logic stating that the airflow must be sufficient to ensure a valid measurement by the angle of attack sensors, especially to prevent spurious warnings.
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在这种情况下,飞行员不会相信失速警告因为它表现得和以前他们所学到的内容完全相反;飞行员会本能地拉着杆让失速警告停止,殊不知这样会让情况更加恶化。