Boeing 737 Max Crashes 'Linked' By Satellite Track Data, FAA Says (arstechnica.com)

An anonymous reader quotes a report from Ars Technica: The Federal Aviation Administration issued an emergency order grounding all Boeing 737 MAX aircraft on March 13, citing new data that showed a possible link between the March 10 crash of an Ethiopian Airlines flight and the crash of a Lion Air flight off the coast of Indonesia last October. In an interview with NPR's David Greene this morning, acting FAA Director Dan Ewell said that "newly refined satellite data" from a flight telemetry system had led the agency to make the move. Both Ethiopian Airlines Flight 302 (ET302) and Lion Air Flight 610 (JT610) were recently acquired 737 MAX 8 aircraft, and both were lost with all aboard just minutes after take-off. According to the emergency order issued by the FAA, "new information from the wreckage concerning the aircraft's configuration just after takeoff that, taken together with newly refined data from satellite-based tracking of the aircraft's flight path, indicates some similarities between the ET302 JT610 accidents that warrant further investigation of the possibility of a shared cause for the two incidents that needs to be better understood and addressed."

The source of the data in question is a combination of telemetry feeds from the flights' Automatic Dependent Surveillance(ADS) system. Introduced in the US in 2001 and more widely worldwide in the wake of the crash of Malaysian Airlines flight 370 in 2014, Europe has required most aircraft to carry the UHF-band ADS-Broadcast (ADS-B) system since 2017, and the FAA has mandated ADS-B for most aircraft by 2020. While ADS-B data was initially meant to be picked up by other aircraft and ground stations, it is also tracked by satellites. Other, less-granular telemetry data sent in the subscription-based ADS-addressed/Contract (ADS-A/ADS-C) format, the Future Air Navigation System(FANS), and the Aircraft Communications Addressing and Reporting System (ACARS) are also picked up by satellite.

Comments

FAA is implicated too

[tinkerton]

This was published in november: https://christinenegroni.com/7...
By then it was already clear that Boeing had quietly added a new MCAS antistall mechanism to make the new plane somewhat act like the old plane and in this way allow pilots to switch from the old plane to the new plane without costs of retraining, and the FAA had let it pass.
Since then the MCAS documentation has been made available to the pilots but that is not enough. MCAS has been badly implemented.

737 Max is a frankenstein's monster

[ghoul]

It has fuselage from the 737, Engines from the 787, flight controls from the A320 (the famous plane where the automation led to crashes. Now 737 Max has taken that mantle)

Boeing should have done a clean sheet design as a replacement of 737 instead of putting engines so big on an airframe meant for much smaller engine.

They created and unstable plane and tried to fix it in software.

While this is an approach often used in fighter jets which are deliberately made unstable so that they can change directions easily its not something you do on a civilian airplane. A civilian pilot does not have the reflexes of a fighter pilot to fix things if the computer is misbehaving

To recap the plane was too small for the engines they wanted to put on it. So they put the engines in a cantilevered position so now the center of thrust was significantly away from the centre of gravity and the plane had a tendency to pitch up and stall. To avoid this they added MCAS which would pitch the nose down in case of a stall detection. To detect the stall they used the AoA sensor and in a freshman Fault Tolerant Computing bug depended on only one sensor when they had 2. They made the warning light showing the AoA sensor is broken an option (only American signed up for this option which is probably why American hasnt had a crash). Then to make things worse they didnt tell the pilots. Also in the NG if the auto trim was runaway pulling back on the yoke would disengage the auto trim. With MCAS they changed this. The auto trim would only disengage for 10 seconds and then MCAS would add more trim and it would keep adding more and more trim till the pilots could not counter even if they pulled the yoke all the way back. Again a software bug. Further to make things worse THEY DID NOT TELL THE PILOTS ABOUT THIS CHANGE. So the yoke maneouver does not work so the only maneovour that works is disengaing the trim using the 2 cutoff switches but this only disengages the Auto trim. If the plane is already nose down it doesnt go back to normal trim. Now you have to pull back on the yoke which was not working till a moment ago or spin two manual trim wheels to get the trim back. All this is happening close to ground as MCAS only engages at low speeds found at takeoff.

Boeing could have avoided this in many ways

1) Build a clean sheet design which is stable with the larger engines
2) Failing that build a MCAS which is fault tolerant with multiple sensors or can be countermanded by the pilot by pulling back on the yoke (This is what they are doing now with the software fix). Not ideal for if the pilot is really flying badly now he can stall the plane
3) Failing that tell the pilots about the MCAS system, the change in the yoke behaviour and have them go through difference training.

They did not do 1 as it would cost too much money
They did not do 3 as they wanted to avoid airlines having to train pilots making the plane easier to sell. One of the reasons there are 5000 737 Max orders is that it needs no crosstraining to fly (officially)
They did not do 2 because of sheer laziness or stupidity in the engineering team

So the Engineering team is now fixing their error No 2. But the Exec team's error No 1 and the Marketing team's error no 3 are still not fixed.

Re:737 Max is a frankenstein's monster

[LinuxIsGarbage]

flight controls from the A320 (the famous plane where the automation led to crashes.

Which famous crashes? I only quickly browsed through the List on Wikipedia and the only one that stood out was Lufthansa Flight 1829, that due to TWO faults AoA sensors (unlike 737-MAX's 1 faulty AoA sensor), commanded a nose down stall recovery. Pilots disconnected the system and recovered.

There is Air France 447, on an Airbus A330. There was a sensor malfunction which led to a sensor discrepancy. The plane detected this, deactivated Auto pilot, and switched to Alternate law. Allowing the pilot to operate outside the protected operating envelope that people blame fly by wire on. They pulled the nose up, the plane responded to the command, told them they were going to enter a stall, then let them enter a stall, and the plane continued to respond to their command for nose up elevator, with 100% thrust, in a stall, all the way from 38,000 ft to the ground. You also had poor crew management where they were both trying to fly the plane with opposing commands on the controls. How should the plane know how to react to such poor crew resource management?

You do also have the A320 that successfully ditched on the Hudson. One of the only cases of a commercial jet successfully ditching.