7 ms·
Yeah, I've seen examples of that in the past. The 737 Max incidents were fertile ground... However, to come at it from the other side. If we assume the RAT did
by VBprogrammer 1y ago
Yeah, I've seen examples of that in the past. The 737 Max incidents were fertile ground...
However, to come at it from the other side. If we assume the RAT didn't deploy, and by implication there was no loss of engine thrust. What could have brought the airplane down? Certainly it wasn't a loss of control incident.
This AAIB conclusion makes interesting reading:
> The operator realised that the flap mis-selection event to G-EZEW was not an isolated
event and carried out a study into similar incidents with assistance from the manufacturer.
The operator was concerned about the risk associated with aircraft being in a low energy
state near to the ground, including performance risks and the possibility that crew members
would become confused leading to a loss of situational awareness.
> Information from the manufacturer indicated that properly-computed takeoff performance
calculations, combined with the aircraft’s Alpha/Speed Lock and Alpha Floor protection
functions, would allow the aircraft to climb safely following a flap mis-selection event, even
when combined with other, adverse, factors. Aircraft climb performance following early flap
retraction would exceed one engine inoperative climb performance.
To be clear, that is a conclusion reached on the smaller A319/A320 Airbus aircraft but I'd be surprised if the conclusion was not similar on the 787.
- foldr 1y agoMy wild guess (which, to be clear, is no better than all the uninformed speculation that I’m complaining about) is that (i) some kind of software fault caused both engines to throttle back to idle and that (ii) the RAT didn’t actually deploy and all the RAT commentary is a red herring. Otherwise I don’t see how to explain the fact that thrust (or lack thereof) appears to have been symmetrical throughout the flight. Both engines failing is already unlikely, but both failing at exactly the same moment? It seems incredible that any kind of failure internal to each engine could be the cause. Surely in that case we’d observe at least a momentary rudder deflection, if not a visible yawing motion of the aircraft itself.
- VBprogrammer 1y agoYeah, I initially wondered about a botched single engine failure. It's not uncommon in twin piston and turboprop aircraft for someone to shutdown the good engine. It is less common in turbofan aircraft because their performance is typically pretty good, even one engine out, and there is no immediate need to manage the dead engine. As you say, the complete lack of any unintended yaw motion and lack of any evidence of failure of either engine in the videos make it seem less likely. An auto-thottle cock up does seem like a likely, if scary, scenario. Two competent pilots on a CAVOK day losing a plane under complete control just by failing to advance the throttles manually. I'd prefer a mechanical fault.
- foldr 1y agoI see that the WSJ now claim to have a source inside the accident investigation for deployment of the RAT: https://www.wsj.com/business/airlines/boeing-787s-emergency-power-system-likely-active-before-air-india-crash-148b7e02 https://www.wsj.com/business/airlines/boeing-787s-emergency-... Looks like dual engine failure really is the most likely scenario.
- VBprogrammer 1y agoGlad I don't own any Boeing shares at the moment...