[dingaling]

I have less ire for Boeing than I do the FAA.

There was an interesting comment on airliners.net that the USSR operated new airliners on freight services for several years before putting them on passenger services. So far I've confirmed that for the Tu-154 trijet, for example, which flew freight for two years before taking a revenue passenger.

But in the West there has always been a tension between certificating for safety versus commercial imperative. Why hasn't the 737Max been grounded pending investigation? Because that would lead to companies losing money. Why would the FAA care about that? Because it considers manufacturers and airlines as 'stakeholders'.

[matt4077]

They have grounded aircraft before, so we know they aren't inherently opposed to that.

I would tend to trust the FAA, given the rather impressive track record of aviation. The difference from "Oh, the humanity!" to today, where North America and Europe have entire years without fatalities is astonishing. It's even more impressive considering passenger-miles/p.a. increased by something like 3 or 4 orders of magnitude.

So it would seem that the FAA is doing a rather good job with these decisions. And "not considering airlines as stakeholders" may sound sensible, but is actually a phrase devoid of meaning: If you want to consider safety only, you or I or the Russians could come up with the trivial (and only correct) solution, which is to ban air travel.

Having flown with regional carriers in Russia during my (and their) wild times in the 90s also makes your praise of their processes suspicious of being parody. I personally saw a pilot take a sip from a suspiciously small bottle of clear liquid. But my seat neighbour reassured me: If you think it's dangerous to fly with a drunk pilot, you should see the way he flies when he's sober!

[sokoloff]

> If you want to consider safety only, you or I or the Russians could come up with the trivial (and only correct) solution, which is to ban air travel.

This would be a safety failure. Banning air travel is overwhelmingly likely to increase transport fatalities. It would decrease air travel fatalities, but would not represent an increase in safety.

"The National Highway Traffic Safety Administration (NHTSA) supported the FAA's decision [to not require tickets for pax under 2 years old] based on current FAA and NHTSA studies that show a mandate could result in another 13 to 42 added family member fatalities over 10 years in highway accidents." - [0]

[0] - https://www.faa.gov/news/press_releases/news_story.cfm?conte...

[WalterBright]

> Why hasn't the 737Max been grounded pending investigation?

Because jumping to conclusions is not helpful. Let the NTSB do their job and find out what went wrong.

[simion314]

>Because jumping to conclusions is not helpful. Let the NTSB do their job and find out what went wrong

We are used from previous cases that aircrafts will get grounded until we are sure the airplane is not at fault. So why in the past this happened before the investigation was complete but in this case the risk is considered t be minimal? I am not saying that it is right or wrong but I want to understand the algorithm that is used to decide what to do in this cases.

[ubernostrum]

We are used from previous cases that aircrafts will get grounded until we are sure the airplane is not at fault.

To be clear: you're suggesting that grounding an entire type of aircraft, either worldwide or even just within US airspace, is a common response to accidents?

I ask because the last general grounding of a type was in 2013 to remedy the 787 battery issues. Prior to that, the last such grounding was the DC-10 in 1979.

[simion314]

Sorry, my experience was with incidents in my country and my memory could also play tricks on my.

Anyway the question still stands, who and how decides if we should ground some airplanes?

[ubernostrum]

Airlines can voluntarily ground their planes. Manufacturers can recommend it. Generally, only a government agency can force it and they only do so in truly extreme circumstances (often requiring multiple serious incidents). More commonly in the US, a directive will be issued to airlines telling them to carry out some remedy (fix/replace a part, change a procedure, etc.) and a window of time in which to complete it. They don't speculatively ground entire air fleets every time there's a potential problem.

For example, in 1991 a Boeing 737-200 crashed in Colorado with the loss of all lives on board. In 1994 there was another crash of a 737, in Pennsylvania, again killing everyone on board. In both accidents the investigation pointed to unexpected movement of the rudder.

Several other cases were identified where pilots claimed the rudder was moving unexpectedly, but they were able to land safely.

The follow-up took several years of investigative work, and eventually identified a situation where a servo could jam and deflect the rudder.

Despite two severe crashes and many other suspected non-fatal incidents, that generation of 737s was not grounded; the remedy, once the cause had been determined, was an order from the FAA to replace the servos, with a timeline by which the replacement had to be completed.

[WalterBright]

The Smithsonian channel runs a weekly show "Aviation Disasters" which shows in detail how this is done.

[VBprogrammer]

I'm almost certain that the solution in this case will be training. Almost exactly as you've said in another comment. The correct response to an commanded stabiliser movement is to set the stab trim switch to cutoff. Pilots will probably experience this failure mode in their next recurrent training.

The accident is more than likely to be attributed to a system being added without sufficient guidance being added to the PoH, some degree of maintenance failing on behalf of the airline and finally a failure of the pilots to identify an issue and take appropriate action.

It's unlikely that those particular holes in the cheese will line up again in the near term given the emergency AD. No reason to ground the fleet.

[WalterBright]

That does seem likely, but very often the eventual cause discovered by the NTSB was not what people initially thought it was.

It's still worthwhile to warn the pilots about uncommanded movement and reiterate what to do about it. At this point I doubt any 737 pilot doesn't know about this.

To add to your summation, I'd expect the mechanism's inability to detect a faulty angle-of-attack sensor needs addressing.

[gpm]

Exactly, jumping to the conclusion that it is safe is not helpful.

Grounding the plane is exactly the opposite of jumping to a conclusion. It's declaring "we can't conclude that this plane is safe".