Friday, 2 June 2017

Some reflections on 'Sully'

The movie 'Sully' received some criticism for taking artistic licence with the NTSB inquiry, and the NTSB complained about how they were portrayed. Additionally, some of the cockpit actions were criticised as incorrect - not according to procedure. This note rebuts such complaints and criticisms.
When I hear 'failed to follow procedures' this is the picture that comes to mind.

It is as important to examine appropriateness of the procedures as it is to examine the appropriateness of the crew behaviour.
There were no procedures for the situation they faced (See Airbus report here), so criticism of flap selection seems more than niggardly hindsight. This article has the following:
"The NTSB recommended changing the location of the rafts to ensure capacity for all passengers, since it's unlikely the rear rafts would be available. The FAA rejected that, saying that if Sullenberger had followed Airbus' directions on descent speeds for ditching, the rear rafts would have been usable. The NTSB said the ability of pilots to achieve those descent speeds has never been tested and can't be relied on. "
There are also questions as to the extent the investigation recommendations have been acted on.
As regards the NTSB moaning about being seen as adversarial, this from the scriptwriter has the ring of truth to it.
The key was, I had to do three layers of research," he says. "One was everything about the NTSB investigation, two was Sully's book...but then really the third level was memorizing Sully and Sully's willingness to share the stuff that he had not shared before - what he went through that was behind the scenes, that's was the wrenching and crushing investigation, the attempt, not out of ill will, but the honest attempt to try and find something that would affix blame. That’s really what they were looking for. You know, you look at 99 percent of these cases, the investigation, it always says at end, ‘pilot error.’ That’s the expectation even if someone is not going to speak that that's somewhere in the bloodstream of the investigation - pilot error. There was no pilot error to find. But it didn’t keep them from looking.”
Recall the press release for the incident report on Flight 447; it put 'human error' on the front pages of newspapers round the world (or at best 'pilot and technical error'). If you read this compelling analysis of the incident, a different picture emerges:
  • Two co-pilots flying rather than pilot/co-pilot, with #3 pilot as Flying Pilot.
  • The Air Data System froze (a known problem). Type Approval for Air Data Systems had not changed since the days of propellor aircraft flying at half the height and half the speed. This caused the Flight Computer to go into some sort of emergency mode.
  • None of this had been in the training and simulation for the pilots.
  • The Flying Pilot held the joystick right back; the other pilot would not have been aware of this, since the joysticks weren't coupled.
  • The hindsight interpretation of the stall warning appears to be controversial. It would appear that the manufacturer was keen to state that the situation facing the pilots was straightforward (i.e. human error) "The situation was not ambiguous and the stall was obvious,". The BEA investigators did not think matters were so straightforward, see here and here. Not surprisingly, there were 66 pages of discussion at PPRuNe
A remarkable incident of pilots vs. automation, where the pilots survived to tell their side of the story, can be found here.
To quote Sidney Deker 'Human error is a symptom of trouble deeper inside a system' - a consequence not a cause of accidents.

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