The Armory - Guns, Knives, and Axes

[heydaralon]

They figured out what happened to the Lion Air 737 Max.

https://www.bloomberg.com/news/articles ... -e0dbq22Rc

AOA probe was repaired by a contractor in Florida. Installed on the aircraft in Bali. Never worked from the time it was installed. Faulty AOA probe sent false signal to, I suppose, whatever you call an Air Data Computer on that thing. ADC would have sent bad angle of attack data to whatever they call a Flight Control Computer on the 737 Max. FCC then realizes (falsely) this thing is in trouble and took control, trying to correct for an angle of attack that was not the actual situation.

AOA probe should have been bench checked at the depot that allegedly repaired it. Looks like they did not. Maintenance guys in Bali should have ops checked it after they installed it. They obviously did not. Aircrew failed to realize what was happening in time when the automated flight control system kicked in and pitched down. Three fuck ups lead to a crash.

This is why I refuse to fly commercial. It's a terrible industry.

I’d check the records and see if the same Bali crew authorized flight of the other crashed plane too.

Here is the problem, if what you say is accurate, and Bloomberg isn’t just trying to make news without having all the facts... it’s still human error that caused this.

It may have been mechanical in nature per sey, but it was overlooked or ignored due to humans.

Why the Auto Pilot couldn’t be turned off while in flight still has not been answered either.

They would be different crews. It is not known yet for certain if the Ethiopia aircraft crashed due to a bad AOA probe, since they have not yet found one of the two on the Ethiopian aircraft (each aircraft has two on each side of the forward fuselage).

Nor have they yet connected the Ethiopian AOA probes to the same Florida repair shop. It is possible the AOA probe went bad on its own, or a different repair shop essentially CnD'd an AOA probe without fixing it and shipped it off to the Ethiopian airline.

It is also quite plausible to me that maintenance crews installed bad AOA probes and ran an improper ops check, assuming they just work (I never saw an AOA probe go bad and the ops check for that sucks almost as much as testing the pitot probes).

The MCAS system is not autopilot in the sense that you are thinking (flying to waypoints), but an automated system that kicks in to save the plane before it is about to stall. This airframe is inherently unstable and needs CAS system to augment manual flight controls. Because this thing can potentially pitch up and stall, this MCAS system was designed to detect that high angle of attack and automatically pitch the nose down.

But if the AOA probe gives the Air Data Computer bad data, then the Air Data Computer sends the wrong angle of attack to the flight control computer. When the flight control computer thinks the plane will stall, it engages MCAS, which pitches the nose down. Since the aircraft was in a level flight, MCAS pitches the plane straight towards the ground.

Aside from the terrible maintenance failures, there are two obvious design failures here:

1) They did not account for the condition of a bad AOA probe when designing this "feature" (rather than a feature, it is a workaround for a poor design decision to make this aircraft unstable) in design. The air data computer must have received two different angle of attack readings from its two probes, and the flight control computer should not have automatically nose dived the jet when it should have had the conflicting data and known that pitching down could endanger the flight.

2) We now know that when MCAS pitches the nose down, it can be impossible for the crew to recover no matter what they do. This is perhaps the most frightening fact that has come out, since it indicates this entire airframe is inherently dangerous. There is no fixing that in an adequate way. Just more MCAS solutions like the one that just crashed two jets. This could be one of the biggest aerospace engineering fumbles if all time if the FAA declares that airframe inherently unsafe.


I could add a third meta design problem:

3) Do not fucking design passenger airliners like they are fighter jets, for fuck sake. An airliner should be stable. It should just want to fly in a straight line and not need complex technical solutions to maintain level flight.

taking out combat, are fighter jets more unsafe to fly then passenger ones?

[Speaker to Animals]

I’d check the records and see if the same Bali crew authorized flight of the other crashed plane too.

Here is the problem, if what you say is accurate, and Bloomberg isn’t just trying to make news without having all the facts... it’s still human error that caused this.

It may have been mechanical in nature per sey, but it was overlooked or ignored due to humans.

Why the Auto Pilot couldn’t be turned off while in flight still has not been answered either.

They would be different crews. It is not known yet for certain if the Ethiopia aircraft crashed due to a bad AOA probe, since they have not yet found one of the two on the Ethiopian aircraft (each aircraft has two on each side of the forward fuselage).

Nor have they yet connected the Ethiopian AOA probes to the same Florida repair shop. It is possible the AOA probe went bad on its own, or a different repair shop essentially CnD'd an AOA probe without fixing it and shipped it off to the Ethiopian airline.

It is also quite plausible to me that maintenance crews installed bad AOA probes and ran an improper ops check, assuming they just work (I never saw an AOA probe go bad and the ops check for that sucks almost as much as testing the pitot probes).

The MCAS system is not autopilot in the sense that you are thinking (flying to waypoints), but an automated system that kicks in to save the plane before it is about to stall. This airframe is inherently unstable and needs CAS system to augment manual flight controls. Because this thing can potentially pitch up and stall, this MCAS system was designed to detect that high angle of attack and automatically pitch the nose down.

But if the AOA probe gives the Air Data Computer bad data, then the Air Data Computer sends the wrong angle of attack to the flight control computer. When the flight control computer thinks the plane will stall, it engages MCAS, which pitches the nose down. Since the aircraft was in a level flight, MCAS pitches the plane straight towards the ground.

Aside from the terrible maintenance failures, there are two obvious design failures here:

1) They did not account for the condition of a bad AOA probe when designing this "feature" (rather than a feature, it is a workaround for a poor design decision to make this aircraft unstable) in design. The air data computer must have received two different angle of attack readings from its two probes, and the flight control computer should not have automatically nose dived the jet when it should have had the conflicting data and known that pitching down could endanger the flight.

2) We now know that when MCAS pitches the nose down, it can be impossible for the crew to recover no matter what they do. This is perhaps the most frightening fact that has come out, since it indicates this entire airframe is inherently dangerous. There is no fixing that in an adequate way. Just more MCAS solutions like the one that just crashed two jets. This could be one of the biggest aerospace engineering fumbles if all time if the FAA declares that airframe inherently unsafe.


I could add a third meta design problem:

3) Do not fucking design passenger airliners like they are fighter jets, for fuck sake. An airliner should be stable. It should just want to fly in a straight line and not need complex technical solutions to maintain level flight.

taking out combat, are fighter jets more unsafe to fly then passenger ones?

Yeah, they are much more complicated and there is a lot more pressure and combustion packed inside those engines.

Fighters do not have much lift without a lot of thrust, so if your engines cut out you have much less time to sort shit out.

[heydaralon]

They would be different crews. It is not known yet for certain if the Ethiopia aircraft crashed due to a bad AOA probe, since they have not yet found one of the two on the Ethiopian aircraft (each aircraft has two on each side of the forward fuselage).

Nor have they yet connected the Ethiopian AOA probes to the same Florida repair shop. It is possible the AOA probe went bad on its own, or a different repair shop essentially CnD'd an AOA probe without fixing it and shipped it off to the Ethiopian airline.

It is also quite plausible to me that maintenance crews installed bad AOA probes and ran an improper ops check, assuming they just work (I never saw an AOA probe go bad and the ops check for that sucks almost as much as testing the pitot probes).

The MCAS system is not autopilot in the sense that you are thinking (flying to waypoints), but an automated system that kicks in to save the plane before it is about to stall. This airframe is inherently unstable and needs CAS system to augment manual flight controls. Because this thing can potentially pitch up and stall, this MCAS system was designed to detect that high angle of attack and automatically pitch the nose down.

But if the AOA probe gives the Air Data Computer bad data, then the Air Data Computer sends the wrong angle of attack to the flight control computer. When the flight control computer thinks the plane will stall, it engages MCAS, which pitches the nose down. Since the aircraft was in a level flight, MCAS pitches the plane straight towards the ground.

Aside from the terrible maintenance failures, there are two obvious design failures here:

1) They did not account for the condition of a bad AOA probe when designing this "feature" (rather than a feature, it is a workaround for a poor design decision to make this aircraft unstable) in design. The air data computer must have received two different angle of attack readings from its two probes, and the flight control computer should not have automatically nose dived the jet when it should have had the conflicting data and known that pitching down could endanger the flight.

2) We now know that when MCAS pitches the nose down, it can be impossible for the crew to recover no matter what they do. This is perhaps the most frightening fact that has come out, since it indicates this entire airframe is inherently dangerous. There is no fixing that in an adequate way. Just more MCAS solutions like the one that just crashed two jets. This could be one of the biggest aerospace engineering fumbles if all time if the FAA declares that airframe inherently unsafe.


I could add a third meta design problem:

3) Do not fucking design passenger airliners like they are fighter jets, for fuck sake. An airliner should be stable. It should just want to fly in a straight line and not need complex technical solutions to maintain level flight.

taking out combat, are fighter jets more unsafe to fly then passenger ones?

Yeah, they are much more complicated and there is a lot more pressure and combustion packed inside those engines.

Did you ever get to ride in any of the planes you worked on? My buddy worked on the KC 135 (the refueling plane for fighters in the air) and he got to ride in it. there was a window and a spot where you could lay on your stomach and watch the fighters in formation refueling behind the plane. One would refuel why the others were like guarding it, then it would roll out and the next one comes in. I have seen youtube vids and it is pretty fucking awesome.

[Speaker to Animals]

Not an F-15. But I was in a KC-135 and C-5.

[heydaralon]

Not an F-15. But I was in a KC-135 and C-5.

Those C-5's are pretty awesome too. Where the cockpit folds up and you can drive a tank in there. I've always wanted to ride in one of those. Are military planes more turbulent than civilian 747s?

[Speaker to Animals]

Not an F-15. But I was in a KC-135 and C-5.

Those C-5's are pretty awesome too. Where the cockpit folds up and you can drive a tank in there. I've always wanted to ride in one of those. Are military planes more turbulent than civilian 747s?

the C-5 was. You have to walk around with oxygen bottles.

[heydaralon]

Not an F-15. But I was in a KC-135 and C-5.

Those C-5's are pretty awesome too. Where the cockpit folds up and you can drive a tank in there. I've always wanted to ride in one of those. Are military planes more turbulent than civilian 747s?

the C-5 was. You have to walk around with oxygen bottles.

Was it cold? I've heard the cargo holds of military planes get pretty cold.

[Speaker to Animals]

Those C-5's are pretty awesome too. Where the cockpit folds up and you can drive a tank in there. I've always wanted to ride in one of those. Are military planes more turbulent than civilian 747s?

the C-5 was. You have to walk around with oxygen bottles.

Was it cold? I've heard the cargo holds of military planes get pretty cold.

There is a pod up at the top of the C-5 for people that is pressurized a little and heated. If you climb down the stairs to the main cargo arra it is cold, but you go down there at your own risk during flight. If the plane hits turbulence you could fall two stories onto a cargo pallet or something.

[heydaralon]

the C-5 was. You have to walk around with oxygen bottles.

Was it cold? I've heard the cargo holds of military planes get pretty cold.

There is a pod up at the top of the C-5 for people that is pressurized a little and heated. If you climb down the stairs to the main cargo arra it is cold, but you go down there at your own risk during flight. If the plane hits turbulence you could fall two stories onto a cargo pallet or something.

Riding in one of those planes is badass as fuck. Overall, taking out the health problems that you experienced later, did you enjoy your time in the military?

[Speaker to Animals]

Was it cold? I've heard the cargo holds of military planes get pretty cold.

There is a pod up at the top of the C-5 for people that is pressurized a little and heated. If you climb down the stairs to the main cargo arra it is cold, but you go down there at your own risk during flight. If the plane hits turbulence you could fall two stories onto a cargo pallet or something.

Riding in one of those planes is badass as fuck. Overall, taking out the health problems that you experienced later, did you enjoy your time in the military?

A lot of fun and a lot of bullshit at the same time. The flight line is soul crushing in the long run.

Just saw this in an aircraft maintenance group. It's similar shit in the USAF.