British Ban the 737 Max

[GRG55]

Re: British Ban the 737 Max

some american pilots were quoted this morning as saying they'd had incidents of the nose suddenly going down on takeoff, and they had to disable the autopilot to correct it. it might be a software problem.

Entirely possible.

"...The anti-stall system on the Max 8 uses payload weight, center of gravity location and airspeed, and under certain combinations of those conditions will modify the pitch trim under high angle of attack conditions (e.g. low stall margin) to modify (increase) the stick force feedback to the pilot, to signal the pitch down..."

Takeoff involves high weight (max fuel quantity), high angle of attack, low airspeeds at minimum altitude. Exactly the situation where one most wants to avoid an excessive angle of attack approaching a stall. Maybe certain configurations on takeoff invoke the anti-stall pitch down, in accordance with whatever "laws" the MCAS is programmed to execute. Perhaps that is a software error. I'm sure it will eventually come out.

But once again, if the behavior of the aircraft under the influence of the computers is inappropriate the pilots should be disengaging/disabling them because the 737 can be flown without them by any competent pilot.

One of my brothers is a Boeing 787 pilot. He has flown a lot Boeing/McDonnell Douglas aircraft, including the 737, 767, MD-11 and the F-18 Hornet. He made the observation that many of the Airbus pilots had difficulty transitioning to the Boeing systems when in the 787 simulator. These two families of airplanes have completely different philosophies as to the pilot's role and interactions in the airplane. Boeing expects the pilot to be an integral part of the entire aircraft systems architecture. Airbus expects the computers to protect the airplane from the pilot doing stupid things. There's no finer example of that philosophy difference that examining what happened to AF447.

[GRG55]

Re: British Ban the 737 Max

It's likely more nuanced and subtle than that. That nose-down MCAS system only actuates on rare occasions, and there are some claims that it's not obvious to the pilots when the system has engaged and how it might be working against their commands.

Mike's original post about the flight properties is based on facts. When Boeing designed this version of the 737, to get a valuable fuel economy improvement they accepted a tradeoff -the aircraft does have some tendency to pitch nose up due to the reasons Mike mentioned, engines of larger diameter mounted further forward and higher up. The nose down MCAS system was designed and installed to counteract this new handling tendency on those unusual occasions when the aircraft gets near stall. The whole situation seems like a tangled set of issues involving handling characteristics, the human factors of cockpit workload and awareness, and training and communications. Most modern air disaster require a few unusual things to happen all at the same time.

Although right now the spotlight is on that nose-down MCAS system, the investigation is not complete and we could be wildly incorrect about about what really caused this crash. That MCAS system might not have played a role at all.

This.

It's never "one thing". It's always a confluence of factors that conspire to create the outcome.

[touchring]

Re: British Ban the 737 Max

This.

It's never "one thing". It's always a confluence of factors that conspire to create the outcome.

Might be component failure. Could be unintentional or possible even sabotage by a state actor. I won't discount that. Nowadays the parts are really bad. Or the manufacturing supply chain might have been compromised.

[Mega]

Re: British Ban the 737 Max

Grounded till May/June

[jk]

Re: British Ban the 737 Max

https://twitter.com/trevorsumner/sta...34362531155974

[Thailandnotes]

Re: British Ban the 737 Max

https://twitter.com/trevorsumner/sta...34362531155974

If this analysis is correct, Boeing is in for more than a 12 percent stock slide. It is borderline criminal and there must be potential whistle-blowers who knew it was not possible.

[GRG55]

Re: British Ban the 737 Max

https://twitter.com/trevorsumner/sta...34362531155974

From my earlier post:

...The anti-stall system on the Max 8 uses payload weight, center of gravity location and airspeed, and under certain combinations of those conditions will modify the pitch trim under high angle of attack conditions (e.g. low stall margin) to modify (increase) the stick force feedback to the pilot, to signal the pitch down.
There's nothing new or untested about the system. However, it is not triple redundant. The 737 remains an airplane that still depends on the pilot, not banks of computers, to fly it. Apparently a radical approach these days, given my reading of some of the news reports.
In the event of a trim run-away or other similar system failure, it actually requires the pilot to recognize and disable the system (remember this is not a fly-by-wire airplane with computers, instead of humans, running the show)...

In the case of Air France 447 the Airbus A330 triple redundant heated pitot tubes all failed.
In the case of Turkish Airlines 1951 the Boeing 737-800NG dual radio altimeters did not resolve and the crew failed to maintain airspeed after the autothrottles retarded a second time.
In the case of Ethiopian Airlines 302 it may turn out the B737 Max 8 single MCAS angle of attack sensor failed.

The point is the technology is remarkably reliable, even without redundancy. The number of commercial airline flights that daily deliver passengers safely to their destination attests to that.

But the technology is not absolutely reliable, even with triple redundancy. And it never will be. That is why we still have pilots in the airplane. Perhap the recurrent simulator emergency training excludes the failure of systems that the engineers think "can't possibly fail", or "can't possibly fail that way"? In all three of these cases the pilots never figured out what had gone wrong, and in every instance they will never have another chance to.

[Techdread]

Re: British Ban the 737 Max

From my earlier post:

But the technology is not absolutely reliable, even with triple redundancy. And it never will be. That is why we still have pilots in the airplane. Perhap the recurrent simulator emergency training excludes the failure of systems that the engineers think "can't possibly fail", or "can't possibly fail that way"? In all three of these cases the pilots never figured out what had gone wrong, and in every instance they will never have another chance to.

This seems like an optimising problem, with computers both in the design phase and implementation phase you can make a plane that would not normally be flyable, flyable.
Boeing went a bit too far on this plane, without the proper re-training of the pilots which they also tried to optimise away.

All in the name of fuel efficiency.

[Mega]

Re: British Ban the 737 Max

Well, Airbus use "Fly be wire" & the F16 has had a long service record with this system.

Talk round the camp fire is FAA is looking at 2 things:-
Pilot Training:- Lack of, rushed or incomplete
The Plane itself:- Boeing has it is said document produced by the themselves for private use that questions the saftly of the plane.............if true then its a BOMBSHELL.........."Ford Pinto" monment.

Mike