4 ms·
The problem is largely fixable. Interconnect the two AoA sensors so they can validate each other and add some logic to detect failures like we've seen where the
by rtkwe 8y ago
The problem is largely fixable. Interconnect the two AoA sensors so they can validate each other and add some logic to detect failures like we've seen where the AoA suddenly jumps to an extreme position and add an indicator or audio alert for that situation. Also modify the cutout to only disable the MCAS inputs so pilots can fix the MCAS trim adjustments using the electronic trim instead of having to use the manual wheels. Finally limit the total trim amount like they originally had in the FAA approval process.
Those together should prevent more crashes. It doesn't fix the underlying problem that the MAX8 has fundamentally different handling properties during climbs that were papered over by a black box but they should prevent it from causing crashes with training.
- salawat 8y agoYou're assuming that MCAS has physically/logically discriminated inputs, and that the electric motor driver is capable of filtering which ones to acknowledge based on a switch that no one knew would need to exist at design time. Odds are, when looking at the avionics network traffic, signals from the trim switches and MCAS are indistinguishable. Running an extra wire to represent the input to the microcontroller would also be a hardware change, which likely means swapping out hardware boards, and running new cable/wire/etc, which will require new schemata, new boards to be sourced from the manufacturer, more paperwork and testing, more maintenance install/refurb procedures, so on and so forth. From my understanding, Boeing is desperately trying to squeak by with just a software change to avoid all that. Personally, I'd prefer they take the time to do it right and change the hardware. It's what should have been done in the first place.
- rtkwe 8y agoI didn't mean run a switch to the motors but either to the MCAS itself or whatever does the mixing between the MCAS and the other trim adjustment sources. Is the MCAS system even a separate box or just a software routine running on the main flight computers taking the AoA data?
- salawat 8y agoMost likely a software routine, which is why I don't think there's any way to disable MCAS without running a new input to the microcontroller board. Not close enough, but my mental engineering department simulator suggests a monolithic approach seeing as it would be cheaper hardwarewise. Wild ass guess mind, to the point of being useless. I couldn't give any concrete insights without access to design docs and specs.