Fiordland

Here is a write up on some of testing they are planning to do with less experience pilots at the US airlines. https://www.reuters.com/article/us-e...-idUSKCN1VC28R

canopus27

For those who are just skimming the news .... the latest failures that the FAA found (a few weeks ago), do go pretty deep into the rabbit hole of possible problems.

ref: https://www.seattletimes.com/busines...ight-controls/
Obviously this should all have been discovered long before now ... but credit where it's due, that's a pretty significant test.

RangerNS

It's a significant test,and a normal one that they had previously decided to skip. You don't get credit for doing normal after several hundred people died.

As to the TC peeps aboard the flight today, maybe they were testing wifi bandwidth.

bimmerdriver

I don't recall where I read it, but in a further description about this particular type of test, the article said there are no recorded instances where a bit has randomly flipped in the manner the scenarios are testing.

canopus27

Did they actually skip that test before? Don't get me wrong, I'm not defending Boeing, nor am I disputing you ... but my read was just that the new variation here was not that the "bit flipped" test was new for the MAX, but rather that this time they had specifically selected bits to flip based on the new understanding of the MCAS. Which, obviously, they didn't realize before was going to be a problem.

canopus27

Yes, I read the same. Which is, I think, as it should be -- you test to more extreme conditions that you ever expect to see in real life.

I don't believe that extreme turbulence actually rips the wings off planes, either .... but they still test wings to the point of failure.

jaysona

Unable to say, but FTPs are being performed.

TCCA is responsible for certification Canadian registered operators, and since this 737-8 issue has resulted in mass hysteria of the plebs, this has gone from a minor safety issue to a major political issue. As such, TCCA is being sure to appear to be in the lead for Canadian related certification activities, as various news outlets are filing FOIA requests on a regular basis.

"No fix yet" is a pretty bold assertion to make by someone not working for Boeing. Just because another useless web forum filled with misinformation - written by people who do not even know what it is they do not know - does not mean work is not actively being performed. There is a lot of being done on this issue, and Boeing is under no obligation to satisfy the idle curiosity of a few plebs that think they are more knowledgeable about a topic than they actually are.

The only people Boeing need to communicate with at this point in time are the various regulatory agencies and various operators, and quite frankly, the less that is disclosed publicly at this point, the better. There are far too many ignorant vulturous media personnel ready to print exaggerative & sensationalist drivel just to get a few more eyeballs.

Bit flipping (as well as fuzzing) tests are extensively performed, however humans can only anticipate so many scenarios, now that a new scenario has been identified, a specific bit flipping series of tests has been designed to address the previously unidentified scenario.


No, wings are tested 150% of maximum load, if the wings do not break at 155% of maximum load, people get fired (I unfortunately heard the screaming sessions by VPs as people were being stripped alive and summarily escorted out of the building) and the wings get redesigned such that they break at 150% of maximum load.

canopus27

So noted - although that's still consistent with the core of my comment, which was that testing is done to levels that exceed what is expected to be encountered in real life.

bimmerdriver

As far as I recall, the test was performed, but I don't think it was performed during a phase of flight where MCAS was operational. That's the difference in the new test.

codfather

I would say MCAS was not looked at any more closely than any other system on the plane during initial tests. Only after the crashes did they decide to really scrutinize the system, too little too late!

jaysona

PeterK

I wouldn't be surprised if a failure rate for the AOA vane was used which turned out to be not statistically accurate in an operational context vs. the lab/analysis environment where it was likely generated, but that's probably not going to turn out to be the overriding issue. My guess is that Boeing assumed pilot recognition of a trim runaway as the mitigation for an MCAS fault. Unfortunately (and especially in the Lion Air crash where MCAS information was not circulated) this presented differently enough from trim runaways in training that the crews were not able to:

1) Recognize it as an intermittent trim runaway and
2) Properly, under stress, execute the proper trim runaway procedure

The assumptions the airframers make of flight crew's ability to accurately and quickly diagnose rare and unusual signals, even with training, may just be overly optimistic. We saw that with AF447 and even in a more simple situation with Colgan Air 3407. Human factors is definitely a still-evolving science.

RangerNS

There is also 3) (after knowing about the procedure, and correctly trying to implement the procedure)

3) Being physically able to manipulate the controls.

CZAMFlyer

"Minor safety issue"? "Mass hysteria"? Anyway...

These statements are not at all in tune with the public expectations of businesses - large or small. If corporations think that being honest, transparent, and up-front is somehow not in the public interest, they need to step up to the current century of public relations. If Boeing believes that the flying public doesn't need to be satisfied their new airplanes won't porpoise into the ground, then all hope for the company is indeed lost. If the aviation experts consider their customers as plebs, that in itself speaks volumes about a broken culture.

We've all seen the tendencies of many media outlets to sensationalize, and the primary reason they do so is because of an information vacuum: the affected company hasn't been willing or smart enough to get out ahead of the issue and present the facts as known. There may be legal ramifications of presenting too much information, but a competent media relations team working in conjunction with the legal team, should be able to craft a worthwhile update to the public. I think sometimes they forget it's the public who are riding in these things.

Boeing and its so-called experts have utterly failed on delivering a safe product in the Max, and more than a few VPs and above need to be stripped down and escorted from the building.

PeterK

True. Though it may be rightly argued that Boeing expected the crews to continue applying other normal procedures to maintain control of the aircraft during execution of an emergency procedure. The crew leveling off at low altitude with the throttles firewalled and the overspeed clacker sounding away may not be something that was anticipated, and perhaps rightly so, since the crew would be expected to take action to keep the aircraft below Vmo whenever they are flying.

Now I don't think the blame lies with the crew in the second crash, but I'm pointing that out to say that it was a convergence of events. The normal trim runaway emergency procedure SHOULD have worked in this case, just as it SHOULD work properly for a more 'normal' trim runaway. The fact that it didn't is due to aircraft AND crew/training AND human factors.