[External] Re: What do you think about this airline vs 5G brouhaha?

Thu Jan 20 18:45:20 UTC 2022

On 2022-01-20 00:49, Mark Tinka wrote:
> Furthermore, the AoA "Disagree Alert" message that would need to 
> appear on the pilot's display in the case of an AoA sensor failure, 
> was an "optional extra", which most airlines elected not to add to the 
> purchase order, e.g., Air Canada, American Airlines and Westjet all 
> bought the extra feature, but Lion Air didn't.

There were a huge number of failures at Boeing in the MAX/MCAS program; 
it's clear the program if not the whole company was rotten to the core; 
but this isn't quite an accurate characterization of that particular 
failure.

The AOA DISAGREE alert was never intended as an optional feature. 
However either due to a software bug or miscommunication between Boeing 
and their contractor for the avionics package (Collins?), it got tied to 
the optional AoA (value) indicator. This was caught *by Boeing* and 
reported to the contractor, but Boeing instructed them not to fix the 
problem and defer it to a later software update 3 years later, and never 
bothered to notify operators or the FAA about the problem.

Somehow it's even worse this way. I don't think a working DISAGREE alarm 
would have saved the flights, though.

Keenan