Boeing 737 Max Software Fixes Due to Lion Air Crash Delayed
I'm not a pilot in any shape or form but just watched Simon Calder on Sky News tell the world about what the software should do. So why didn't the software cut in on this demo flight at Farnborough or for that matter on the Lion Air and Ethopian flights?
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I'm not a pilot in any shape or form but just watched Simon Calder on Sky News tell the world about what the software should do. So why didn't the software cut in on this demo flight at Farnborough or for that matter on the Lion Air and Ethopian flights?
737 Max demo
737 Max demo
Pegase Driver
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, Yes the shot is taken from behind with a strong zoom distorting the angle. , plus the aircraft is empty with little fuel, so acceleration must be phenomenal . I wonder what is the thrust-to-weight ratio in this configuration compared to a first generation 1950-60 military jet ?
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, Yes the shot is taken from behind with a strong zoom distorting the angle. , plus the aircraft is empty with little fuel, so acceleration must be phenomenal . I wonder what is the thrust-to-weight ratio in this configuration compared to a first generation 1950-60 military jet ?
In this case, the MCAS may or may not have been in operation, it’s not an anti stall device, it just adjusts the handling characteristics in pitch to match that of the earlier models by subtly repositioning the stab as needed during high AoA manoevres.
The accident aircraft were suffering from erroneous AoA input which moved the stab continuously Airplane Nose Down. It would be safe to assume that the demo aircraft was fully serviceable and the MCAS if in operation was operating correctly.
The accident aircraft were suffering from erroneous AoA input which moved the stab continuously Airplane Nose Down. It would be safe to assume that the demo aircraft was fully serviceable and the MCAS if in operation was operating correctly.
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BREAKING: A Boeing-led review of a stall-prevention system suspected in the deadly crashes of two of the company’s new 737 Max jetliners has detected an additional software problem that the FAA has ordered fixed before the planes are cleared to fly again, the company acknowledged Thursday.
Additional software problem detected in Boeing 737 Max flight control system
the most concerning this from my perspective is the way Boeing is playing down the issues....
Boeing called the additional problem, which is unrelated to the stall-prevention system,“relatively minor.”
Two officials familiar with the FAA investigation said the issue is nonetheless classified as critical to flight safety.
Additional software problem detected in Boeing 737 Max flight control system
the most concerning this from my perspective is the way Boeing is playing down the issues....
Boeing called the additional problem, which is unrelated to the stall-prevention system,“relatively minor.”
Two officials familiar with the FAA investigation said the issue is nonetheless classified as critical to flight safety.
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Because they were flying with flaps extended. MCAS does not engage with flaps extended.
Take a glider pilot and put her/him into light single, stall it and their reaction will always be to point the nose at the ground before reaching for the throttle lever.
MCAS has probably activated multiple times already, but with a working AoA sensor. It would have trimmed down once then gone back to sleep.
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I am a glider pilot and we never use the spoilers in a stall. Point the nose down and then rase it before the airspeed increases excessively. You really need to anticipate the increased air speed. On landing yes the spoilers do behave like a throttle. They can give us a lot more range if it is needed.
At least that is what we do in a Schweitzer 2-33A.
At least that is what we do in a Schweitzer 2-33A.
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I am a glider pilot and we never use the spoilers in a stall. Point the nose down and then rase it before the airspeed increases excessively. You really need to anticipate the increased air speed. On landing yes the spoilers do behave like a throttle. They can give us a lot more range if it is needed.
At least that is what we do in a Schweitzer 2-33A.
At least that is what we do in a Schweitzer 2-33A.
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Unbelievably shocking information drip feeding out now. Lawyers for the families of the deceased are going to have a field day, several different groups of defendants potentially emerging:
https://www.reuters.com/article/us-e...-idUSKCN1RA0DP
https://www.reuters.com/article/us-e...-idUSKCN1RA0DP
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Is there any way to bring the "yoke jerk" back to the Max? Maybe with a harder pull, so normal MCAS response isn't affected?
AoA vanes keep failing, https://www.heraldnet.com/nation-wor...-had-problems/ Got to handle that in Fault Detection & Isolation software well. Even when 2 AoA vanes freeze up to about the same AoA reading! --> 2014 Lufthansa 1829 - Bilbao.
Looking at several accidents like these Max ones, incidents including Qantas 72 ( https://www.youtube.com/watch?v=H3q5S9PCoJA ), etc., what's needed is an easy, quick, one-button (shielded) way to tell the airplane: Turn off all automatic movements of any aero control surface and throttles. Pilot only, proportional control, direct and quickly done.
AoA vanes keep failing, https://www.heraldnet.com/nation-wor...-had-problems/ Got to handle that in Fault Detection & Isolation software well. Even when 2 AoA vanes freeze up to about the same AoA reading! --> 2014 Lufthansa 1829 - Bilbao.
Looking at several accidents like these Max ones, incidents including Qantas 72 ( https://www.youtube.com/watch?v=H3q5S9PCoJA ), etc., what's needed is an easy, quick, one-button (shielded) way to tell the airplane: Turn off all automatic movements of any aero control surface and throttles. Pilot only, proportional control, direct and quickly done.
Ttfn
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Surely not! Glider stall recovery requires the pilot to simultaneusly push forward on the spoiler lever while pitching nose down. The glider pilot - any pilot - in a light aircraft should be flying manoeuvres with one hand on the throttle - which works in exactly the same sense as the spoiler on a glider - and vv.
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Ralph Nader calls for an appliance style total product recall. His logic is effectively that an undesired byproduct of the plane's design (over pitch up) should've never left the design sheet. I.e. if a kitchen appliance had a tendency to over-heat, the manufacturer wouldn't be able to get away with installing fire-protection material to combat a fire, but would be forced to redesign the appliance to not over-heat in the first place.
https://www.npr.org/2019/04/04/70999...=1554469797383
https://www.npr.org/2019/04/04/70999...=1554469797383
A second software problem
But later Thursday, Boeing confirmed to The Washington Post that it had found a second software problem that the Federal Aviation Administration has ordered fixed —
One of the officials familiar with the investigation said that everyone wants a thorough review now, as the worst outcome would be to have another problem emerge later. “You don’t want to be in a situation where there was one contributing factor to an accident, and then three weeks later you find another” problem that could impact a flight.
In a statement, Boeing called the additional problem “relatively minor” but did not offer details of how it affects the plane’s flight-control system. “We are taking steps to thoroughly address this relatively minor issue and already have the solution in work to do that,” it said. Washington Post.
Whatever this problem is, it does not improve confidence in the design and certification checking process, and probably indicates limitations in system simulation and evaluation, which apart from flight testing ‘real’ failure conditions and validating crew procedures may leave gaps in the understanding.
One speculative item is slat signalling / inhibition, which diagrammatically appears related to AoA. This was identified in Pprune threads (tech log?) in the technical discussions after the Lion accident (FDR evidence).
If so, then the new problem could be how to limit the extent of AoA failure for some systems, but not others.
MCAS (and slats) to be limited, but the full (failed) range of AoA used in ‘the highest one wins’ logic required to meet ‘fail safe’ (misnomer) approval in other systems such as stick shake - and the interaction with low seed awareness etc.
This again identifies the inherent problems of only having two sensors.
One of the officials familiar with the investigation said that everyone wants a thorough review now, as the worst outcome would be to have another problem emerge later. “You don’t want to be in a situation where there was one contributing factor to an accident, and then three weeks later you find another” problem that could impact a flight.
In a statement, Boeing called the additional problem “relatively minor” but did not offer details of how it affects the plane’s flight-control system. “We are taking steps to thoroughly address this relatively minor issue and already have the solution in work to do that,” it said. Washington Post.
Whatever this problem is, it does not improve confidence in the design and certification checking process, and probably indicates limitations in system simulation and evaluation, which apart from flight testing ‘real’ failure conditions and validating crew procedures may leave gaps in the understanding.
One speculative item is slat signalling / inhibition, which diagrammatically appears related to AoA. This was identified in Pprune threads (tech log?) in the technical discussions after the Lion accident (FDR evidence).
If so, then the new problem could be how to limit the extent of AoA failure for some systems, but not others.
MCAS (and slats) to be limited, but the full (failed) range of AoA used in ‘the highest one wins’ logic required to meet ‘fail safe’ (misnomer) approval in other systems such as stick shake - and the interaction with low seed awareness etc.
This again identifies the inherent problems of only having two sensors.
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Ralph Nader calls for an appliance style total product recall. His logic is effectively that an undesired byproduct of the plane's design (over pitch up) should've never left the design sheet. I.e. if a kitchen appliance had a tendency to over-heat, the manufacturer wouldn't be able to get away with installing fire-protection material to combat a fire, but would be forced to redesign the appliance to not over-heat in the first place.
https://www.npr.org/2019/04/04/70999...=1554469797383
https://www.npr.org/2019/04/04/70999...=1554469797383
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CW427's point re adding fire protection material to to flaky kitchen appliance is spot on. However, it seems not to apply to Boeing. Batteries overheating/bursting into flames? No problem. Put them in a fire resistant box. Job jobbed! Never mind fixing the bursting into flames issue!
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Boeing boss: http://news.sky.com/video/share-11684695
Trust is broken. CEOs legally crafted statement rings too little too late.
Need to get back to how they conducted initial testing, and it's thoroughness, and how this airframe received it's CoA. A lot of key questions need investigation.
Trust is broken. CEOs legally crafted statement rings too little too late.
Need to get back to how they conducted initial testing, and it's thoroughness, and how this airframe received it's CoA. A lot of key questions need investigation.