Bohemian1

Maybe. But that requires a lot of insight into the actual design parameters which most of us do not have.

But keep in mind that older and "inherently unstable" planes like the F-117 and B-2 fly just fine (and fast) because of sophisticated fly by wire systems. Aircraft stopped being analog a long time ago.

5mm

Stranger

Of course no conspiracy, more like bean counters indulging in wishful thinking and insisting in pushing the limits of an antiquated frame beyond its limits, too quick and too cheap. But widhing thinking only will do until things happen. As to competitiveness, the point remains that the competitive strength of the Max was that it was cheap. But the past tense may end up sticking. Noe it is becoming clear that they bought cheap and the indeed got cheap. In some ways this reminds me of the competition between the DC-10 and the L1011. Former was rushed to market with major issues and turned out to be a poorly desgined lemon while the L1011 was a good design. Except of course the Max is not going to kill the 320Neo. Might kill itself instead as you say when comparing with the E90.

ffsim

Presumably it would be up to TC to collect that data, analyze it, and make that decision.

My opinion on airlines that have already voluntarily grounded their fleets is that they're doing so not out of "an abundance of caution" but rather because they're placating their customers' (possibly irrational / premature / unwarranted / unjustified) fears. Basically, it's a marketing decision rather than an engineering one. And, as such, there's no right or wrong answer -- maybe it's the right call for their customer base, maybe it isn't.

taupo

My understanding of the Max issue it is with regard to the AOA and the autopilot. The aircraft thinks it is entering a stall so creates a nose down attitude to prevent the stall.

Boeing issued bulletins about this and enhanced training was put onto the airlines and pilots for awareness of this, disengage AP and carry on.

Problems as I see them, the aircraft shouldn't behave this way to begin with and some airlines training is better than others.

I wouldn't hesitate to fly an AC, WJ, BA Max

Stranger

More a basic philosophical design issue than a complex dynamics one though. Stability. Coming to that:

The fly by wire thing is merely an enabling thing, otherwise orthogonal to the issue of stability. As you point out, indeed military planes are unstable by design, which increases their agility. Because the airbus design was based from scratch to rely on computes for envelope protection etc., they are closer to the stability limit than previous designs. For instance you notice that their empennage looks small. But still they are within the stability limit. As I mentioned previously, the BAC-111 tuned out to have a stability problem, the deep stall situation, but that was discovered after it was already in service, and it took one crash to have it dealt with, although also as a bit of a bandaid thing. But the Boeing folks knew the new engines on the Max could lead to a pitch up situation that could increase the angle of attack to the point where the wings would stall, and that the horizontal stabilizer, the small wing in the tail, was too small to be able to counterbalance. They instead decided to keep the old tail that was too small and instead implemented in software a fix whereby if the angle of attack would become too large, hence risking an uncontrollable stall, the nose would be pushed down, I believe using the trim. To add insult to injury, the based this only upon the signal from a single angle of attack probe. Disregarding that these primary devices (including pitot probes) are invariably the weakest link. One has to scratch one's head, wondering where their engineers were.

smallmj

AC Website is now showing AC860 cancelled tonight.

BOH

IIRC, only one prior incident over Windsor ON in 1972 of the cargo door opening in flight. Plus I don't recall the DC10 was grounded post the TK crash in 1974. It was after the AA crash in 1979 at ORD that grounded it for a while. Whilst the cause of the engine separation was blamed on faulty AA maintenance, this should not in itself have caused the aircraft to crash.

It was the uncommanded (and un-indicated in the cockpit) leading edge slat retraction on the wing (due to severed hydraulic lines) that had lost the engine that caused the wing to stall and subsequent crash. Despite AA being blamed for the original engine separation issue, mandatory changes were also issued to McD-D to install one-way (no return) valves in the slat hydraulic lines to prevent uncommanded retraction in the event of pressure loss. IIRC, both L1011 and 747 already had these.

CZAMFlyer

I know nothing about the stability or lack thereof of the horizontal stab. I was referring to the MCAS issue that is being blamed for the Lion Air crash, and the subsequent issuing of the procedures in how to negate it. If the software fix is to address horizontal stab concerns, then I've got my Max issues conflated.

Maybe it's as simplistic as soothing the cattle. But I'd expect those fears extend into the boardrooms, and some executives are thinking three steps ahead and wondering about their own liabilities in the event they face blowback from continuing to operate the aircraft beyond the point where suspicions were raised. Those suspicions gain credibility when shared by the regulators in the UK, Australia, Singapore and South Korea. There's also the possibility that some regulatory agencies are making a political statement (China?).

Simon

German, French, Irish, Omani airspace are now closed to the 737MAX.

Stranger

The MCAS thing was implemented as a cheap fix to a major stability issue. True that most of the talk focuses on how poorly it was implemented, not so much on how it should never have been there in the first place.

chebert999

SWA just decided to let passengers change their flight for free if they are worried on flying the MAX but not grounding them (yet). Maybe AC should do the same. It would be a good PR move.

cairo604

ffsim

AA's cabin crew union told its members yesterday that they're allowed to opt out of working the 7M8 if they want without penalty. All airlines should offer that tho their crews and customers. As you say, it's a solid PR move.

skybluesea

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