And that difference led to two crashes?

Garry - I suggest you re-read those specs.
The fuselage height & width have remained constant since "day 1" on the 737 at 4.01m & 3.76m respectively.

English units are quoted differently 13Ft 2In height vs 12Ft 2In.

No. That's US units. England doesn't measure length in feet and inches anymore in design.
The US together with Liberia and Myanmar are countries that have not declared the metric system to be official:)

English units are quoted differently 13Ft 2In height vs 12Ft 2In.

Didn't NASA lose something pretty critical because they couldn't handle units conversion?

Regardless of height & width of the sensors, they did not disable the power to the trim controls!

English units are quoted differently 13Ft 2In height vs 12Ft 2In.

Didn't NASA lose something pretty critical because they couldn't handle units conversion?

And didn't an aircraft crew turn turn a cruising passenger jet suddenly into a glider for that same reason with their fuel?

Cheers.

Yep & thankfully, one of the flight crew was ex air force & knew of an airfield that would enable them to land safely. There have been numerous incidents over the years where ex Forces personnel were flying the aircraft concerned, used both their training & knowledge to put those aircraft on the ground safely.

Further confirmation that profits 1st holds sway in the matter of civilian training.
iirc 22,000lbs should have been put in but instead it was 22,000 litres which equals 38,938.96 lbs.
Sorry about the changes, conversion gets me at times (had it near enough right the 1st time).

I cannot understand what the difference in measurements have to do with MCAS & the other issues surrounding 2 fatal crashes. Unless anyone can provide evidence that those differences were part & parcel of those crashes, desist in discussing them.

Regardless of height & width of the sensors, they did not disable the power to the trim controls!

Quite correct. The crew in the second did and then against the book put the power back!

BTW did anyone notice that the MCAS system would not activate if the aircraft was dirty?* So just when was that first pitch down commanded? Most pilots like to clean up the airplane once positive rate of climb is established and there isn't any more runway under them. That is within a couple hundred feet of the ground. If I'm reading the reports right the system did not activate then. It only activated after the plane had gained some altitude. Begins to make me wonder because if the AOA sensor was bad, why wasn't it bad as soon as data was being taken when the gear came up and the flaps were retracted? I suppose it is possible it did, but the pilot flying was using the electric trim in small bursts at the time so the delay timer prevented MCAS from activating. A good long hard look at the raw FDR data is needed to really understand this.

I don't know if the AOA sensors survived the crashes in good enough shape to be tested. Was it a mechanical failure, sticky, or a electric failure, bad connection? Unless this root cause is found, then there is no fix. Making MCAS not respond isn't a fix for bad sensor design or construction. It just might crash a plane for the very reason MCAS was put on the airframe.

Oh and didn't the crew on the Lionair flight before flag the AOA sensor for mechanics to look at? Did they? What if anything did the find?


*dirty, flaps and/or landing gear deployed.

AOA sensors are "very exposed" by design, and on (older) b737 are not very easy to clean properly, but can be damaged during cleaning (I would assume that using a long brush on a stick would be a "bad idea", and that an access ladder (or cherry picker) would be needed.
Generally pilots will use the trim controls in bursts of a few seconds, and allow the aircraft to settle before trying again.
Given both the LionAir & Ethiopean aircraft were in very steep dives I doubt that the AOA sensors have survived in any meaningful states.
Good question about when the AOA mismatch (duff sensor) was first detected on either flight - the FDR should show that.
With only two sensors the failure of one is a bad situation, how do you know which one is right - even if one is end-stopped how do you know if that is the right one or the wrong one?
The initial concept was that MCAS would only ASSIST pilots, by making the b737Max fly with the same handling as the older b737 generations and in no way to prevent a stall, just make a stall "feel" the same as it did - stall prevention would have made MCAS a "safety" system from the out.


BTW - Has anyone else noticed similarities between the Grenfell Tower fire and the b737Max crashes? OK, the obvious one is that too many people died, but the one I'm talking about is that "design corners" were cut to save money (cladding that was not up to the job, an aid that went wrong in a bad way)

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

BTW - Has anyone else noticed similarities between the Grenfell Tower fire and the b737Max crashes? OK, the obvious one is that too many people died, but the one I'm talking about is that "design corners" were cut to save money (cladding that was not up to the job, an aid that went wrong in a bad way)

Yes.

And both were changes to working, fully "designed", systems. The corners could be cut because changes were not given the same level of scrutiny as brand new designs.

BTW - Has anyone else noticed similarities between the Grenfell Tower fire and the b737Max crashes? OK, the obvious one is that too many people died, but the one I'm talking about is that "design corners" were cut to save money (cladding that was not up to the job, an aid that went wrong in a bad way)

Yes.

MCAS was introduced by Boeing on the 737 Max 8 because its heavier, more fuel-efficient engines changed the aerodynamic qualities of the workhorse aircraft and can cause the plane's nose to pitch up in certain conditions during manual flight.

It seems MCAS is also good at producing kinetic energy.
With the world heading towards more & more automation, what would have been the results if both those flights were under automatic control? How would MCAS have operated?

what would have been the results if both those flights were under automatic control? How would MCAS have operated?

IIRC, MCAS is deactivated in auto-pilot modes. So unless you want to count the weight of the software and manual pages ...

The failed AOA may or may not have activated the stick shaker. Different software, fly by wire system.

BTW, MCAS isn't the only stick pusher, BAC-111's have such a system as well as do most T-tail jobs.

...and the Airbus A32x family, which is due to the very high AoA these can safely achieve in "normal" flight situations. Just don't exceed the limits as they did at Paris where Airbus learnt a very painful lesson....

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

IIRC, MCAS is deactivated in auto-pilot modes.

Understood. However, does that mean the AoA sensors are ineffective in auto mode? If not, how does auto mode deal with AoA sensor failures?

IIRC, MCAS is deactivated in auto-pilot modes.

Understood. However, does that mean the AoA sensors are ineffective in auto mode? If not, how does auto mode deal with AoA sensor failures?

I'm not sure the auto-pilot uses input from the AoA sensor. In a lot of aircraft they only turn on the stick shaker and the warning horn. In small aircraft they are just a switch, on or off. Too high or not too high. Wouldn't surprise me to find out they are just a switch on the Max.

Yes. There is a switch. But...
Citing Boeing’s Bulletin, “On the outside of the yoke in front of both the pilot and the first officer, there is a switch for electrically controlling the trim – the angle of the stabilizers. If the pilot understood what was happening, he could have used that switch for a few seconds at a time to counteract what the M.C.A.S. was doing to the stabilizers. But that would have been only a temporary solution: the pilot has to release the switch or the nose could go too high. But if he releases the switch, the anti-stall system would reactivate a few seconds later”…..
http://newsinflight.com/2018/11/18/mcas-boeing-737max8-stall-recovery-system/

apparently they aren't just a switch on the 737 but input is fed into the SMYD (stall management yaw dampener) computer.
https://aviation.stackexchange.com/questions/31882/how-does-one-test-a-stall-warning-during-pre-flight/31883
Also they have been redesigned over the years as their heaters have been subject to unexpected and undetected failure and subject to AD's.

A brief update on the news for the Boeing 737 MAX:


Even if the FAA clears Boeing 737 Max jets to fly, Americans may not get on board

... As Elwell makes his case for the rest of the aviation world to trust the FAA when the agency is ready to deem the 737 Max ready to fly again, new research shows Americans are leery about setting foot on the Max – even when it's cleared to fly....

... Boeing has hired a PR firm to help restore trust in the Max and plans to rely heavily on pilots as a show of confidence in the plane but some pilots are saying they're not interested in being arm candy.


The Boeing 737 Max's return to the air has reportedly been delayed by regulators looking into emergency procedures on older Boeing jets

... the FAA is evaluating the emergency procedures for not only the Max but also the older generations of the 737, including the hot-selling Boeing 737 NG.

According to the officials, the broadened evaluation will take a look at how pilots of all 737 variants are instructed to respond to emergency situations...


FAA will move first to approve the Boeing 737 MAX to fly again, possibly within weeks

... the head of the Federal Aviation Administration (FAA) made clear Thursday that his agency will move first to lift the order grounding Boeing’s 737 MAX. While he steered clear of specifying a timetable, his comments suggested such clearance could come as early as late June...

... Safety regulators elsewhere will make their own decisions after looking at the FAA’s data, he said. Some will accept it, while “other countries have already decided they will not only review our work but look at some other things of interest to them.”...

... it’s possible that Transport Canada will require simulator training for the MAX changes...



Read into that what you will...

All in our only one world,
Martin

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See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

To me, this reads like there is no safety culture after Management pressure and interference has pushed people around:


Engineers say Boeing pushed to limit safety testing in race to certify planes, including 737 MAX

... The removal from the MAX program of the FAA’s Authorized Rep who insisted upon stricter engine fire-suppression testing is briefly summarized in a February 2017 report...

... The engineer removed from the program had more than two decades of experience at Boeing doing certification work on behalf of the FAA. Managers transferred him to Boeing’s “Central Engineering” unit, with no particular job description, and appointed as his replacement on the MAX team an engineer with relatively little experience in certification.

Four additional concerns specific to the 737 MAX were listed in the 2017 report. All were related to certification of legacy systems inherited from the earliest 737 models that were found by FAA technical staff to be noncompliant with the latest safety regulations...



All a game to rush and push to boost bonuses and safety be damned?

All in our only one world,
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

My answer to that is: Has the MCAS "patch" been tested in real time on a real aircraft or on a simulator?