Ethiopian Airlines ET 302 Boeing 737 Max 8

Ethiopian Airlines ET 302 Boeing 737 Max 8

It has happened again. Another catastrophic crash of a Boeing 737 Max 8 albeit with a different airline.

The MCAS feature is like those garage door sensors. Trying to mitigate a scenario that is possible but not likely (stall). However, it has lot of false positives. Detects obstructions all the time and kicks back the garage door for no reason. Unintended consequences.Β Assuming that what this is. Another false trigger of stall logic triggering MCAS steep dive.

The previous incident with Lion Air Flight 610 is detailed here:

Lion Air Flight 610 Boeing 737 MAX 8

New York Times is reporting that there were changes made to the control algorithm. Not sure what the reference is to. Original MCAS algorithm or some changes since the Lion Air Crash?

I sure hope the MCAS algorithm was turned off at the least.

Updated Statement by Boeing:

Reuters article on this:

Flight Radar 24 Tweet/blog info:

Stakes are high here for Boeing, the Airlines and passengers.

New York Times is reporting that all Chinese Airlines have stopped using the Boeing Max 8 effective immediately.

Confirmation from WSJ that China is grounding all Boeing 737 Max 8.

What is SouthWest Airlines in the US going to do? Can they turn off the MCAS algorithm effective immediately?

Something to think about though. Given service bulletin’s were sent to all Boeing 737 Max 8 pilots with details on how to override the MCAS.

Indonesia follows China and grounds Boeing 737 Max 8 fleet. More to follow?

Just came across this interesting Seattle Times article. Concurs with my thesis.

FAA will not ground the Boeing 737 Max in the US. Mandates software fix to MCAS by end of April. However,

FAA statement and Continued Airworthiness notification to international community (CANIC). Design change is three pronged for MCAS algorithm.

  1. Activation enhancement
  2. Signal strengthening, and
  3. command limit.

The activation enhancement and command limit can and should be Engineering calibrations.

Signal strengthening requirement implies this is believed to be S/N deterioration issue.

It appears the signal enhancement/strengthening might be requirement to use inputs from both AOA sensors in tandem and modify the algorithm to accommodate all inputs to arrive at a best best possible value for AOA instead of just assuming the worst input as true. This is my educated guess. Since I do not have any inside information.

Updated statement from FAA below. Might revisit the Boeing 737 Max decision if Ethiopan Airlines flight ET302 data shows anything new.

Few questions to consider:

1) Did ET302 have the AOA sensor light? Did it ever come on?

2) JT610 did not have the light.

3) It appears SouthWest and American Airlines have the light

4) what are the airlines doing differently?

5) MCAS does not need the light. It knows there is a mismatch between the two AOA sensors. Needs to figure out the best possible course of action. Being addressed via the Software update in April (see above CANIC)

Grounded!

Ethiopian Airlines has chosen to send the black boxes to BEA in France. Interesting development given that Air France Flight 447 crash investigation by BEA led to the following Β fixes in Airbus:

 

  1. Stall “Alarm” algorithm logic redesign and new software
  2. Pitot tubes redesign and new supplier
  3. Cockpit protocol changes
  4. Pilot training

The Boeing 787Max issue is now linked to its MCAS algorithm which is an anti stall system!!

To be continued…

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