Without having a chance to fully do the math, how does the 737 do per flight hour? I'd expect it to be marginally higher than the bigger jets on a per flight hour basis, too, given the 737 will have far more take off and landings.
There's a whole lot of 737s out there through the decades, so it's easy to make them look unsafe depending on how you count.
"The following airliner models are ranked by the rate of fatal passenger events per million flights.":
Plane crash rates by model
Slightly old data, but....
No, they didn't.
Quite likely it's the AOA splits.
The stabilizer trim IS what reinstates the center, giving a neutral stick in whatever flight regime - high or low speed, flaps up or down, forward CG or aft CG. It has significantly more force available than the elevator itself.
It has? I haven't seen that yet.
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Thanks, Graham, interesting in both pointing in the same direction as my point and how much safer modern aircraft are.
Yes - I've seen the 737 described as a plane to avoid - which totally ignores the simple massive amount of flight time it's had...
This is an interesting analysis:
Bjorn’s Corner: ET302 crash report, the first analysis - Leeham News and Analysis
This is an interesting analysis:
Bjorn’s Corner: ET302 crash report, the first analysis - Leeham News and Analysis
C Darwin - I was commenting on your comment, "the Ethiopian pilots followed the correct prescribed procedure repeatedly." The part "repeatedly" is not correct.
The link gpauk provides in post #546 is fantastic, and also look at this - Satcom Guru: What happened on ET302?
Do understand that the Flight recorder traces in these analyses are what's been provided by the investigating authority, do have tons of good information, but are by no means complete. They are wanting to show a very specific narrative. There's also no complete cockpit voice recorder transcript. You are welcome to assume what you like with this incomplete information.
The link gpauk provides in post #546 is fantastic, and also look at this - Satcom Guru: What happened on ET302?
Do understand that the Flight recorder traces in these analyses are what's been provided by the investigating authority, do have tons of good information, but are by no means complete. They are wanting to show a very specific narrative. There's also no complete cockpit voice recorder transcript. You are welcome to assume what you like with this incomplete information.
Two very interesting articles thank you both for posting them. I know a lot more now and also know a bit more about how little I actually do know 
Interesting that in previous versions of the 737 You could switch out autopilot control of the trim motors and keep manual control from the yoke, but not in the max. To the uninitiated that seems an odd decision.
The bit I am still slightly confused over that I have to go research is that which AoA sensor to be used changes each time the plane powers up. I haven't worked out if this is just the sensor or the whole 'side' that is selected. And would one normally expect there to be a manual over ride to swap over. This is just interest from my Satcom days where you designed something to keep working until the last part died by switching stuff around and bypassing broken things. Vital where things go up and don't come down ever.
Interesting that in previous versions of the 737 You could switch out autopilot control of the trim motors and keep manual control from the yoke, but not in the max. To the uninitiated that seems an odd decision.
The bit I am still slightly confused over that I have to go research is that which AoA sensor to be used changes each time the plane powers up. I haven't worked out if this is just the sensor or the whole 'side' that is selected. And would one normally expect there to be a manual over ride to swap over. This is just interest from my Satcom days where you designed something to keep working until the last part died by switching stuff around and bypassing broken things. Vital where things go up and don't come down ever.
A reasonable place to start would be that we don't have a full voice recorder transcript, and the flight recorder info that's been released is seemingly good information, but by no means complete...
That's not phrased very well, so I'm a bit muddy on what your are getting at, but I don't think that's correct...
The FCC changes sides either 1) every flight, or 2) with whichever Autopilot is selected. Gary would know better than I.
When the s**t hits the fan big time there are a lot of discussions that are not shared with the general public. In the case of Boeing we have national pride issues as well so I would be willing to bet good money that the US govt have been in touch and have steered some of Boeings responses.
I would also not expect a lot of the discussions with airlines on this to be shared. The NDAs in aerospace are many and long.
Also lawsuits are starting to fly and first thing Lawyers like to do is limit what is said.
All adds up.
From satcom guru article
"The cutout switch function was changed with the 737MAX from all prior 737 models. The legacy switch combination was one switch to cutout electric trim altogether, the other to cutout the autopilot trim commands. MCAS and Speed Trim System are both commands from the “autopilot”. With the legacy switch configuration, the flight crew can disable the autopilot commands and retain electric trim. With the 737MAX, the flight crew lose both electric trim and autopilot trim with the cutout switch.". Article has pictures to show this.
Thanks. It would (to a non-pilot) make sense that if one autopilot dropped out you would try the other.
Begin Rant.
I find it hard to believe that the 737 max was even certified with what I consider an incomplete system. An optional AoA disagree alert is available. What a joke!!!!
Why on earth would you have an optional monitoring/ warning function?
From my humble experience with aircraft autopilot systems and their failures and most recently,10 years on the AW139, which suffers autopilot failures on a day to day basis…A failure or disagree/ miscompare in the system ALWAYS results in the AP either going off line or failing to come on line, with a resulting warning for the crew, who then fly manually. The aircraft does not try to dive into the ground. I must add that the AW139 has had its fare share of accidents and fatalities but not because of the AFCS.
Most AFCS systems have command inputs and independent monitors, such that at any time part of the AFCS does not agree with what its sensors are saying, the system shuts down. It cannot tell which sensor is telling the truth and thus distrusts both sensors. That is how the 737 max MCAS system should have been as standard!
AW139 Autopilot…
Each AIOP Channel A module (AIOP-A1 and AIOP-A2) provide:
- Command function for the trim actuators and
- Monitoring function for the associated linear actuators.
Each AIOP Channel B module (AIOP-B1 and AIOP-B2) provide:
- Command function for the associated Linear Actuators
- Monitoring function for the Trim Actuators.
Basically, do as your told. If I see otherwise we're not going anywhere and the real Boss has control.
This IMHO is the way the 737 max MCAS system should have been set up. Quote from Agusta A139 training manual…
“The AFCS is designed to be fail-safe because autopilot malfunctions are demonstrated to be safely recoverable by the pilot flying the helicopter manually.
The pilot can override the AFCS at any time by manually operating the flight controls. The system gives the pilot full authority over flight controls regardless of whether the autopilot is engaged or disengaged.”
On the 737 MAX, Boeing removed the “yoke jerk” function that enabled pilots to disable the automated trim system with a hard pull on the control column rather than hitting two cut-out switches on the center console. WTF!!!! You're not even going to tell them that the switches exist? If the crew touch the controls, the aircraft should respond immediately and the AFCS gives up command until the crew lets go of the controls and then resume as before. If the crew use the trim release switches, the aircraft gives up control until the trim is released and then resume in the newly trimmed attitude etc. Not if its a 737 max!
Quote “The Ethiopian Airlines pilots completed the Boeing recommended and FAA approved differences training from the B-737 NG aircraft to the B-737 MAX aircraft before the phase in of the B-737-8 MAX fleet to the Ethiopian operation and before they start flying the B-737-8 MAX.” This training did not include how to deal with the MCAS problem they encountered.
Yared Getachew at 29 years of age had 8100 flying hours. With that sort of experience, how was it possible for the 737 max AFCS to win against his experience unless it was seriously flawed? With so many hours of experience at 29 years old, he was a sky god. Due to inadequate, money scrimping training, he is now with God!
Bless Yared Getachew and his family and all the victims and their surviving families. Screw Boeing and the FAA!!!
If any of my 737 max info is incorrect. Sorry for that!
I could also rant about my dislike for very very large passenger aircraft but that is another rant entirely.
End Rant.
I find it hard to believe that the 737 max was even certified with what I consider an incomplete system. An optional AoA disagree alert is available. What a joke!!!!
Why on earth would you have an optional monitoring/ warning function?
From my humble experience with aircraft autopilot systems and their failures and most recently,10 years on the AW139, which suffers autopilot failures on a day to day basis…A failure or disagree/ miscompare in the system ALWAYS results in the AP either going off line or failing to come on line, with a resulting warning for the crew, who then fly manually. The aircraft does not try to dive into the ground. I must add that the AW139 has had its fare share of accidents and fatalities but not because of the AFCS.
Most AFCS systems have command inputs and independent monitors, such that at any time part of the AFCS does not agree with what its sensors are saying, the system shuts down. It cannot tell which sensor is telling the truth and thus distrusts both sensors. That is how the 737 max MCAS system should have been as standard!
AW139 Autopilot…
Each AIOP Channel A module (AIOP-A1 and AIOP-A2) provide:
- Command function for the trim actuators and
- Monitoring function for the associated linear actuators.
Each AIOP Channel B module (AIOP-B1 and AIOP-B2) provide:
- Command function for the associated Linear Actuators
- Monitoring function for the Trim Actuators.
Basically, do as your told. If I see otherwise we're not going anywhere and the real Boss has control.
This IMHO is the way the 737 max MCAS system should have been set up. Quote from Agusta A139 training manual…
“The AFCS is designed to be fail-safe because autopilot malfunctions are demonstrated to be safely recoverable by the pilot flying the helicopter manually.
The pilot can override the AFCS at any time by manually operating the flight controls. The system gives the pilot full authority over flight controls regardless of whether the autopilot is engaged or disengaged.”
On the 737 MAX, Boeing removed the “yoke jerk” function that enabled pilots to disable the automated trim system with a hard pull on the control column rather than hitting two cut-out switches on the center console. WTF!!!! You're not even going to tell them that the switches exist? If the crew touch the controls, the aircraft should respond immediately and the AFCS gives up command until the crew lets go of the controls and then resume as before. If the crew use the trim release switches, the aircraft gives up control until the trim is released and then resume in the newly trimmed attitude etc. Not if its a 737 max!
Quote “The Ethiopian Airlines pilots completed the Boeing recommended and FAA approved differences training from the B-737 NG aircraft to the B-737 MAX aircraft before the phase in of the B-737-8 MAX fleet to the Ethiopian operation and before they start flying the B-737-8 MAX.” This training did not include how to deal with the MCAS problem they encountered.
Yared Getachew at 29 years of age had 8100 flying hours. With that sort of experience, how was it possible for the 737 max AFCS to win against his experience unless it was seriously flawed? With so many hours of experience at 29 years old, he was a sky god. Due to inadequate, money scrimping training, he is now with God!
Bless Yared Getachew and his family and all the victims and their surviving families. Screw Boeing and the FAA!!!
If any of my 737 max info is incorrect. Sorry for that!
I could also rant about my dislike for very very large passenger aircraft but that is another rant entirely.
End Rant.
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