PPRuNe Forums - View Single Post - Autothrust behaviour with corrupted airspeeds
Old 20th July 2009 | 16:14
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Hyperveloce
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Autothrust behaviour, Declining Airspeeds & SOPs

The following Air Safety Report (sorry, in French) shows that
1) the airspeed was underestimated to 100 kts instead of 280 kts during numerous seconds before the A/THR and A/P were automatically put off like in the AF 447 case: these "numerous seconds" would largely be enought in managed speed for the A/THR to augment the thrust level to max thrust ? (and to initiate an overspeed, to reduce the upper aerodynamic margin)
2) the pilot himself reacts to the stall alarms by pulling down the nose (and initiating a slight turn to get out from these bad conditions).
The corrupted airspeed event duration is, like in other cases, a few minutes (typically 3 or 4 mn). This enabled the crews the regain rapidly airspeeds and a normal law, but what if the AF 447 corrupted airspeed event has lasted 5, 6 or 7 minutes ?

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Last edited by Hyperveloce; 20th July 2009 at 17:35.
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