This is getting curiouser and curiosuer. It seems every day we're getting another data point from the mishap investigation board. What is it, with all these "daily" "leaks"?
Re-posting:
Say what? Boeing didn't advise airlines or the FAA
that it shut off the warning system. Acident investigators have linked
bad data the system is designed to detect to the deadly Ethiopian
Airlines and Lion Air crashes. Color me perplexed.
Boeing Co. didn’t tell Southwest Airlines Co. and other carriers when
they began flying its 737 MAX jets that a safety feature found on
earlier models that warns pilots about malfunctioning sensors had been
deactivated, according to government and industry officials.
Federal Aviation Administration safety inspectors and supervisors
responsible for monitoring Southwest, the largest 737 MAX customer, also
were unaware of the change, the officials said.
The alerts inform pilots whether a sensor known as an “angle-of-attack
vane” is transmitting errant data about the pitch of a plane’s nose.
Accident investigators have linked such bad data to the deadly Ethiopian
Airlines crash in March and the Lion Air crash last year; both planes
lacked the alert system.
Now we learn that even the Boeing 737 Max 8
test pilots were not brought into the loop regarding the new flight control system.
And this: Boeing did not build the "standard" redundancy" into this system.
Links: multiple sources,
including The WSJ yesterday.
So, from my perspective, and I could be really, really wrong, but this is the timeline at which I am looking:
- airlines looking for more fuel-efficient aircraft
- Airbus and Boeing in a huge race; perhaps an existential race
- Airbus takes early lead; in fact, it looks dire for Boeing
- Boeing's hardware design -- overpowered engines on an older fuselage
- the hardware cannot be fixed without huge economic, time loss
- solution: a software fix
- requires a sensor
- instead of "standard" redundancy, uses only one sensor
- one sensor not likely to be the problem but raises questions
- how many pitot tubes does a 737 have? five sets organized into two groups, one group for the pilot and co-pilot and one as a backup; link here;
- problem likely to be with software: system received "correct" information from sensor but interpretation / solution incorrect
- test pilots not involved in significant portion of MCAS development to fix the hardware problem
- on-off switch in hard-to-reach cockpit location
- system turned to "off" without pilot/co-pilot's knowledge
- lack of training at time aircraft put into service
My question: under what conditions do the planes on take-off go ballistic? Cross winds? Tail winds? Head winds? Overweight? Underweight? Unbalanced cargo? Why did two planes crash and thousands (?) did not.
August 19, 2019: expected date for Boeing to place the 737 Max 8 back into service.
