Slashdot Mirror
Boeing Unveils 737 Max Software Fixes (cnbc.com)
hcs_$reboot shares a report from CNBC: Boeing previewed its software fix, cockpit alerts and additional pilot training for its 737 Max planes on Wednesday, saying the changes improve the safety of the aircraft which has been involved in two deadly crashes since October. By the end of this week, Boeing plans to send the software updates and plan for enhanced pilot training to the FAA for certification approval. After the FAA approves the fix, Boeing said it will send the software update to customers.
Among the notable changes to the MAX flight controls:
- The plane's Maneuvering Characteristics Augmentation System, or MCAS, automated flight control system, will now receive data from both "angle of attack" sensors, instead of just one.
- If those disagree by more than 5.5 degrees, the MCAS system will be disabled and will not push the nose of the plane lower.
- Boeing will be adding an indicator to the flight control display so pilots are aware of when the angle of attack sensors disagree.
- There will also be enhanced training required for all 737 pilots so they are more fully aware of how the MCAS system works and how to disable it if they encounter an issue.
if (crashing() && uncrashFeatureEnabled()) {
uncrash();
}
Before engaging MCAS the control software will display an animated dialog:
Clippy: It looks like you're plane may stall. Would you like help?
It must have been something you assimilated. . . .
Because the sensors are physical devices, and are this subject to all physical device problems. They can break, corrode, be bent by a physical impact, etc...
They're regularly inspected, which is about the best you can do.
I don't read AC A human right
As someone that has worked in both functional safety and off-highway vehicles.
How the fuck did this ever make it into production. Why is a 'second sensor' an upsell?
When given the option to completely update the cockpit to the latest and greatest with digital displays.
They chose to replicate the old mechanical dials so the pilots couldn't be retrained.
The entire thing from start to finish was rushed. Mechanical design comes first. There is no 'try and develop software in parallel'. A clean software design depends on a good mechanical design.
The plane should have been a white board redesign, it should have been balanced such that a pilot could fly it stable with no avionics. This isn't a jet fighter.
But it was rushed because Europe invested in R&D and beat them to economy routes. How much money did Boeing C-suites make before 2011? During the 2009 crash there was a hiring spree by some companies because the market was flooded with cheap, good engineers that just got laid off. Companies invested in talent. Did Boeing?
People died because... Boeing sat on R&D from post WWII while making a ton of money so when Airbus released a good plane they scrambled to retrofit an old design by putting huge engines on an airframe causing it to pitch up but to appease its clients it added software to mimic the old plane behavior and tested it themselves and told the FAA they promise they did it right.
More or less.
MCAS wasn't *supposed* to be life critical. Quite the opposite, the Pilots where supposed to be able to override it by grabbing the controls. The problem was that it *became* life critical over time and nobody properly noted the design change's impact and then they failed to see (or just flat ignored) this fact.
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
Why wasn't this done in the first place!? It is an industry standard to use redundancy for life critical applications. They have redundancy already, why didn't they use it?
Also: Applying the patch creates TWO single points of failure for the system. If EITHER of the angle of attack sensors fails, goes off-calibration by more than 5 1/2 degrees, or angle of attack at the two sensors differs by more than that small amount, the MCAS will shut down.
The MCAS is there to bring the nose down if the aircraft is about to stall, which it is prone to do because of the relocation of the engines (relative to the previous model) forward and up, along with the reshaping of their nacelles. With the MCAS shut down the aircraft is back to having a risk of a sudden stall, which can ALSO cause it to have an "uncontrolled flight into ground" if it's too low for the pilots to recover (which is pretty darned high).
As with aircraft carrier naval groups, continents also ALWAYS have the right-of-way over airliners.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
The amount of pitch up with the newer more powerful engines got to a point where when the plane is already at a high angle of attack, the elevator don't have enough authority to counter act it. The entire rear stabilizer needs to be moved using the stabilizer trim.
Other planes have larger elevators or less pitch-up under full thrust.
The MAX 8 will be one of the safest planes in the sky after this design review is done and the software gets updated.
A plane where the engines have to much power and push the nose so far up that the plane can stall: does not sound safe to me.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Actually, it's more confusing, and that's the problem.
If the pilot manually re-trims, MCAS is overridden for 5 seconds, then it adjusts the trim again. It's not hard to see how the pilot might mis-identify the ongoing problem as a recurrent momentary problem.
Per recent reports, the cockpit voice recorder shows that they were in the middle of it.
And according to Boeing's simulations, they only had forty seconds between stick shaker activation and a rapid unplanned deceleration, so...
The depressing (or incriminating?) part here is that the fix didn't require any hardware modifications, as I would have expected. I assumed that there was some cost/weight issue to having the MCAS have access to the left and right sensors. But nope, it could have compared both.
If it can be fixed with a software fix, then it could have been done right from the start without any extra hardware costs of production.
Very damning.
I get so tired of the reports calling clear software/algorithm bugs "computer glitches."
It's akin to blaming every pilot error situation on the plane.
Just as with hardware design flaws, software design flaws should have repercussions for the manufacturer, and not written off as "oh, one of those computer glitches!" If your computers are glitchy, don't put them on my plane, thanks.
Love many, trust a few, do harm to none.