The Seattle Times report reminds me of typical IT projects resulting in a super-GAU (German slang for catastrophe or worst-case scenario) due to management placing higher priority on meeting arbitrary or competition-based timelines than functional objectives, and accepting the potential risks and consequences, which then of course transpire. The difference being that rarely do failed IT projects result in lives lost…. although given the discussion here around MCAS software one could argue that this is/was actually an IT project.
It is rather ironic that this should happen to Boeing, given the way Boeing has always brought forward the pro’s of continuing the use of “manual” or “direct” controls in their aircraft over the fly-by-wire that Airbus migrated to over 20 years ago. In my recollection, the closest Airbus has come to a software-based accident was Air France over the south Atlantic, and that could have been avoided if the pilots were less dependent on the automation (sorry, thread creep).
chflyer wrote:
Articles today on Avweb and The Seattle Times.
That seattle time article is amazing…
It does sound like a bad cockup, although the bit about the FAA delegating certification authority to Boeing is nothing new. It is after all why Garmin bought UPSAT.
So one needs to read a bit between the lines of the journalism. The other day I spent an hour and a half on the phone to the BBC who contacted me re some GA crash, and I carefully explained to them the N-reg angles – and they still got it wrong in their article.
I kind of do not believe that the trim cutout switches actually did something on both Lion Air and Ethiopian crashes. I do not believe that the pilots would not switch the cutout switches and instead of it manually fought turning trim wheels 21 times (in case of Lion Air crash where we already know this information)!!! The cutout switches are so easily reachable. I suspect that the MCAS system was wired in a way that enabled it to turn the trim even though the cutout switches were switched off because it seems too absurd that someone would fight the trim wheel manually so many times instead of flipping the two switches nearby and than moving the trim wheels manually without a need to overcome the electric motors that were moving the wheels in the opposite direction. I am quite curious what kind of information is the accident investigation going to reveal.
Pytlak wrote:
it seems too absurd that someone would fight the trim wheel manually so many times instead of flipping the two switches nearby and than moving the trim wheels manually without a need to overcome the electric motors that were moving the wheels in the opposite direction
We all did it even against spring/aerodynamic trims (go-around or forget to take flaps up) 
My understanding it does not take much too to loose stability on a heavy loaded B737Max/A320Neo while on climb and full power, so you don’t get that much chances to correct for mistakes, by looking at vertical profiles it is hard to decouple aircraft oscillations from pilot/mcas inputs but for sure it did not take too many iterations to dive and crash, but will see what gets revealed by investigators…
Also the fact that aircraft can’t fly (up to certification standard) without MCAS means disabling the thing is not a good idea as the kind of flying you get after belong to test pilots with no pax
The real question do you need normal checklist or the red section 
?
Peter wrote:
So one needs to read a bit between the lines of the journalism. The other day I spent an hour and a half on the phone to the BBC who contacted me re some GA crash, and I carefully explained to them the N-reg angles – and they still got it wrong in their article.
Yes that article could be biased, journalists may pick dramatic wording on internal/external memos/emails between constructors & regulators out of context (I bet you can find similar “catch phrases” if you read communications regarding B787, A320, A380 flying today… )
chflyer wrote:
In my recollection, the closest Airbus has come to a software-based accident was Air France over the south Atlantic,
Not quite. Lufthansa nearly lost a 321 due to – wait for it – faulty AoA readings and the software pitching the plane down. AFAIK there were several incidents like that which led to the replacement of AoA sensors on many Airbusses.
Blimey. One might have expected a gentler ride from Boeing’s hometown newspaper. That article reads as though it was written by someone who understands system safety analysis (or was very well briefed by someone who does) and generally feels as though it could be accurate. It also confirms that while there may be two sensors, only one is used while the other is dormant which is what matters in the safety analysis. We are going through this safety analysis for our new aircraft design at the moment and it is no easy task to understand the design thoroughly, think about all the failure scenarios then classify them. It takes the synthesis of many people’s inputs; deep, honest thinking; training; experience; and a lot of hours in the flight simulator.
Food for thought indeeed.
BTW, the trim cutout switches are just switches. Not a properly rated circuit breakers. I do not have B737 MAX electrical schematic at hand but can imagine that due to the size of motor(s) to move the big trapezoidal rod, which moves the elevator, it is likely that there are relays connected to the switches and those relays than open/close the circuit to the motors. Relays can fail. Relay contacts can weld together (if not silver/carbon combination). The only safe solution to disconnect something is a proper circuit breaker. I can still imagine situation when MCAS kept turning the trim wheels even after the cutout switches were moved to off position.
Can one overpower the servo driving the trim, by grabbing the trim wheel?
In most GA planes you should be able to do that, even if the servo doesn’t have a slipping clutch (the King ones usually have that).
Many years ago I got a cockpit visit in a DC10 (pre 9/11 obviously) and they said you can overpower the servos but it takes a lot of force.
What ever happened to “look at the instruments (gyro horizon) and fly the plane”?
