Within the context of aviation, my confidence in regulators is less than complete. Having said that, I do place complete trust in the professional aviators in command of aircraft operated by the likes of UA - in particular UA an other such legacy carriers. If there's a problem in which they perceive to fall outside of their own ability to safely manage, I expect they'll make that known in some fashion or other, and much sooner rather than later at this point...

What's most likely to me, at this point, is a potential emergency AD to inspect AOA sensors. FAA won't ground a type on speculation and public sentiment (can't speak to other regulators) but to the extent deeper parallels are found with the JT610 crash, I think it's likely urgent action will be taken. Still, the FAA needs to be accountable for any action up to and including grounding a type, so there needs to be some evidence to support their decision(s). Today (and the next few) is a big day for that, IMO.

People are free to make their own risk assessments in the meantime, naturally, and I am by no means concluding that the 737MAX is, without doubt, an acceptably safe airplane. But it's going to take some more evidence-gathering to credibly answer the questions the traveling public has about the safety of the type.

150+ deaths, to be precise. This is not like calculating the risk of a misconnect, where the worst-case scenario involves a forced overnight at FRA. That risk I'm willing to accept. Plunging into the ground at 600+ mph because the pilots can't control the aircraft, on the other hand, is not a risk I am inclined to voluntarily undertake. I think we will see more carriers pulling these aircraft until there are more definitive answers.

Any issue would still need to be sorted out and investigated on. The postponement is about optics.

Yes. It's a very quick and easy procedure. It is a procedure that has existed in every transport jet that I've ever flown and is practiced in simulator training.

By whom? You can't establish anything without applicable data.

An MCAS event will provide ten-seconds of nose-down trim input at half-speed followed by a five-second pause. This cycle will repeat until the condition triggering MCAS is resolved. The result of a nose-down trim input is that it makes the aircraft's nose "heavier" requiring increased back-pressure on the control yoke to hold the nose in its current position. The reason for MCAS is to bias the nose down in situations where the airplane is dangerously slow and in danger of an inflight upset.

When you are hand-flying a 737 it frequently rolling in trim without your input. There are various systems that are doing this for various reasons. MCAS is a new system which can also run the trim when you are hand-flying the airplane. The pilot has no way of knowing which system is responsible for any particular trim input. All we know is that the trim is moving. If the trim is moving in a direction that we do not want we use the trim switches (thumb switches on the control yoke) to correct the mistrim condition which immediately stops any of these inputs and retrims the aircraft toward the desired trim state. Those switches are being used frequently while hand-flying the airplane in normal operations. In the case of MCAS, this starts the five-second pause and will be followed by another MCAS event if the underlying cause of the MCAS activation has not been corrected.

In the first accident flight (Malaysia) the accident crew, according to the released DFDR data, had 26 MCAS events and stopped 25 of them with opposite trim input. What they apparently failed to do was to complete the runaway stabilizer procedure which would have led them to throw the two stabilizer trim cutout switches which are within easy reach of either pilot. This would have stopped all electric trim inputs and left them with manual trim with which they could have completed the flight safely. We don't yet know why they didn't complete the procedure. We also don't know why the airplane was dispatched several times after similar stab trim events without the underlying problem being fixed.

There has not been any information released about this new accident that can either confirm or rule out a stabilizer runaway situation but that is something that will be known quite quickly once the DFDR is found and the data analysed.

I'm uncertain how useful it will be to anyone else, but I found the explanations about the following two incidents provided me good context in which to think about air safety:
1. Birgenair Flight 301 - https://en.wikipedia.org/wiki/Birgenair_Flight_301
2. XL Airways Germany Flight 888T - https://en.wikipedia.org/wiki/XL_Air...ny_Flight_888T

In both cases, instrumentation gave the pilots incorrect information which resulted in a loss of control of the aircraft and the tragic loss of all aboard.

Previous to watching the Air Disasters shows on these crashes, I would have discounted erroneous reporting from any single instrument to cause an experienced commercial airline pilot to lose control of his/her aircraft, but afterwards I feel more aware of how important correct instrumentation is to flying.

I am confident, but not recklessly overconfident, about the expertise, experience, and training of mainline pilots at major U.S. carriers. I'd have no problem with riding a MAX with one of them at the stick. Has any of them chimed in on airliners.net? I'm sure they've been discussing the incidents.

I don't think how they manage their FFP has much to do with their aircraft maintenance record or pilot training. FFP is not a big thing outside of the "first world".

The flight data recorder has been located as of early this morning and some actionable data will be available in short order... that will be the point at which a grounding or emergency inspection/AD can be implemented.

https://onemileatatime.com/airlines-ground-737-max/

Cayman Airlines and Indonesia ground the plane as well. As Lucky says, I'd expect more to come out. Especially if the black boxes show issues similar to the LionAir crash.

Interesting quote from American Airlines in there:

It is premature to call for a fleet grounding or FAA cert revocation (although China has ordered all MAX examples grounded, and ET has parked all theirs). It is quite right to be concerned about the possibility of intrinsic design flaws in the planform, engine config, or software. Too early to tell what's up but you'd be foolish to ignore the data we've got, which is: two similar-profile new aircraft hull losses on climbout in less than five months, nearly 350 dead.

Hark back to the first version of the deHavilland Comet: two hull losses four months apart (in October and March, oddly enough: 1952-53, with a third two months later. The aircraft structure was fundamentally flawed but the Comet remained in service, with two further hull losses in 1954. More aggressive action would have prevented at least the latter three incidents. Hopefully we are a little smarter about risk response nearly 70 years later.

- Mine too. As others have observed, its been enough for China to ground all 97 of its 737-MAX800 fleet. (For those who care, I read it on MSN). I was within hours of booking a flight on one of these, but not anymore. Its been interesting and informative to read the differing views on this thread from those who have more technical expertise on the topic than I do.

I found the response (#2 in the thread) from [MENTION=574963]cmd320[/MENTION] far more helpful than your comment. I obviously did not know the answer else I would not have posted the question. I learn news things in FT all the time.

Down -12% on the open. ~$30B in equity cap gone.

Not gone, unless you are selling shares. the stock market in the short term is not a good yardstick of the value of a company.