I believe there are 2 AOA sensors/vanes (left and right), with multiple sources of input data. Still, only one side/FCC is "active" at a time, and it switches sides for each flight.

There have been other instances of MCAS-related issues on MAX A/C as well, including the previous flight on the ill-fated Lion Air MAX-8. That crew experienced virtually the same thing and dealt with the problem properly by initiating runaway trim procedures (activating stab. trim cut out switches). They flew the remainder of the flight with manual trim and had no further issues (why it was not grounded after that flight is another matter/question).

So, while I think there is little question that the MCAS system needs to be reexamined and scrutinized/tested further, there is still an element of adequate experience and adequate training that also needs to be addressed, IMO.

For instance, there are systems/procedures on that aircraft that were required to be memory-items previously, that are no longer requirements today, primarily due to increasing complexity. Over the years, there have been a number of items added to what amounts to a troubleshooting "quick reference guide". That's all well and good if you have an issue at FL30, but at the more critical phases of flight (take-off & landing), you probably don't have time to be digging for a guide. You'd better have the experience and the applicable procedure should be a second-nature memory item, IMO.

I think there are already 2 on the MAX (left and right)?
Not only that, but I believe it's only "active" when flying manually, and/or with flaps up, and/or with extreme pitch/bank angles. It can also be temporarily overridden via elec. trim switches on the yoke, or manual trim wheels.
Further, it would seem that the standard procedure for runaway trim is applicable to faulty MCAS, albeit a bit updated now.

I can't imagine how/why a pilot would attempt to "fight" a problem like that for any lengthy period of time before initiating runaway trim procedures, all the way to stab. trim cut-out. However, that appears to be a possibility with the Lion Air crew, and maybe even the Ethiopian flight (alt. oscillations noted). As mentioned, the previous crew on the Lion Air A/C had essentially the exact same problem. They dealt with it appropriately and continued their flight without issue.

That said, I still think the big problem is the lack of training/awareness of the new system, and the differences in the initial runaway trim procedure.
As I mentioned previously, one could halt runaway trim on the "old" 737 by simply pulling back on the column (break-away). That won't work on an MCAS equipped A/C. You have to disable the trim altogether (cut-out).
While that was always the final step in the "old" 737 runaway trim procedure, the initial step of pulling back on the yoke no longer works with a faulty MCAS system. Sort of counter-intuitive, IMO.

Yep. Probably just waiting for prelim. info as they had to have help with the data gathering.

The same prelim info from the Lion Air crash is already out there.

I saw on the news tonight (ABC World News) that the Ethiopians wouldn't be doing any examination of the data recorders until the crash site was cleaned up. Sounds pretty flaky to me.

The 737 Max8 Type has been grounded in China, India, Indonesia, United Kingdom, the EU, Australia, New Zealand....about two thirds of the Max8 fleet worldwide is not flying. North American airlines and regulators have declined to ground the aeroplanes.


Several Pilots repeatedly warned federal authorities of safety concerns over the now-grounded Boeing 737 Max 8 for months leading up to the second deadly disaster involving the plane, according to an investigation by the Dallas Morning News. One captain even called the Max 8's flight manual "inadequate and almost criminally insufficient," according to the report.

https://www.zerohedge.com/news/2019-03-12/pilots-complained-about-boeing-737-max-8-months-deadly-crash

Didn't see/hear that. Only that one of the boxes was damaged.
Both Boeing and NTSB go-teams are en-route (or already there) to assist, so I am sure info will come out as soon as humanly possible.

Eric, you could be right. I did not work on 737's, so I'm really not sure. Looking at photos, it does appear to have a pair of pitot tubes and an AOA sensor on both sides.

A lot of what ATC says is repetitive and most of it can be anticipated. You should know what to expect especially if you have been to that airport in the past. My favorite airport to fly into was O'Hare in Chicago. It was the busiest but everyone there was professional and knew where they were, where they were going and what do to when they got there. I use to hear this a lot, "keep 'em spooled up UPS 'cause your next". (for take off) LOL And you had better be ready to go.

The original 737-100 had a long narrow "low bypass ratio" engine that was mounted almost directly under the wing. The newer versions of the 737 had an engine (CFM56) with a very high bypass ratio with a huge fan in front. The diameter of the large fan increased the over all diameter of the engine cowl that wouldn't fit directly under the wing and had to be mounted further forward to clear the ground. The CFM56 accessory package was moved from the bottom of the engine to the side and if you look carefully, you can see the bottom of the engine cowl looks somewhat flat. Here are some pics that might help.
http://forums.pelicanparts.com/uploa...1552454106.jpg
http://forums.pelicanparts.com/uploa...1552454135.jpg
http://forums.pelicanparts.com/uploa...1552454161.jpg
http://forums.pelicanparts.com/uploa...1552454179.jpg

Here's a better side view. http://forums.pelicanparts.com/uploa...1552454356.jpg

I am amazed at the breath of experience we have here on PPOT. If you want to know something, this is the place to come.

When I was an engineer our lab was tasked with investigating material failures on aircraft. There was also an electronics support lab in our building, but no big lab to investigate software failures. I'll bet there is now!

About 40 countries' civil aviation authorities disagree with you.

That may be, although I think the effective number is higher than that, but that doesn’t make them right. We don’t know what brought down the second jet; as for the first one, I think you’d have a hard time blaming Boeing. There were mechanical problems that were not properly fixed, I suspect you’ll find that the pilot training was inadequate and I think you will also find that these Third World Airlines don’t spend the money that the US airlines do, to outfit the jets with the options that would make this problem fairly moot.

Boeing is happy to supply these jets with the angle of attack indication in both the captains’ and first officers’ displays, as well as the HUDS unit. Companies like SW Airlines avail themselves of these options. They also spend quite a bit more money on pilot training, which produces more competent pilots.

I'm not sure this came out all that well in the news coverage, but Lion Air is notorious within the industry for their shoddy maintenance practices. They have been caught on many occasions with "aftermarket" parts on their aircraft. Cheap ass, Chinese made knock-off parts of vastly inferior quality that are not certified by any major regulatory agency, like our FAA. As a matter of fact, their aircraft have, at times, been barred from certain airspaces. The whispered, behind the scenes consensus is that that practice is what led to their crash.

I'm not sure that any avionics, particularly safety of flight type stuff, or pilot aids, are "optional" in any way. They save money with cheaper interior components, like lavs, galleys, and seats, I have seen that. But as far as a downgraded cockpit or pilot/copilot interfaces, that I'm not so sure about. I would be surprised to learn any such equipment is "optional".

https://www.reuters.com/article/us-indonesia-crash-boeing-aoa/optional-warning-light-could-have-aided-lion-air-engineers-before-crash-experts-idUSKCN1NZ0QL

https://theaircurrent.com/aviation-safety/southwest-airlines-is-adding-new-angle-of-attack-indicators-to-its-737-max-fleet/

As for the fake parts, that's been an issue for a while. Hopefully the manufacturers do a good job of weeding those out before they make it onto a plane. What's worse to me is that some airlines outsource their maintenance to companies operating in what I'd call third world countries and I see no way to keep that crap off of those planes.

I'm getting to the point that I pick the carriers I use as much as I pick the planes I fly on.

Thanks for the links. I have to say, even having been around this stuff for awhile, I am surprised to learn something like this "warning light" is optional. Of course it is not the only warning system, but more of a feature to bring your attention to the real warning system, but still...

Looking at the cost of one of these aircraft, I cannot believe this was a financial decision. In other words, its omission was not to "save money" on the purchase of the aircraft. That, and the articles kind of overstate its importance, I'm sure. If properly trained pilots are monitoring systems as they should be, this additional warning feature becomes redundant and unnecessary.

There is a PR angle to this as well. We all know that. Southwest, for example, is not going to ground its fleet and immediately retrofit every one of their Maxes. I would be willing to bet they are still flying many of these aircraft years from now sans this retrofit. This modification will likely be performed "while they are in there" at some upcoming major service interval. Kind of like we would do on our cars.

Let's make sure we are clear about one thing - the manufacturers are not the ones installing "fake parts". That is happening in service, and it's the airlines along with the MRO's (Maintenance, Repair, Overhaul) facilities that are installing them.

And yes, the Third World carriers and MRO's are the culprits here. I would go so far as to say that anything that does not fall under FAA, EASA (Europe), JTSB (Japan), CASA (Australia), and similar First World regulatory bodies are suspect.

I spent most of my time in the field in the Third World. It's the nature of the business - they are the ones least likely to have their own engineering and mechanics staffs. This is all maintenance and what we call "Service Bulletin" (equivalent to automotive "recalls") work. We were obligated, if our mechanics or inspectors found non-OEM parts during the course of their work, to effectively ground the aircraft until replacement OEM parts could be obtained and installed. It got pretty testy at times, to say the least. Lots of money at stake...

Me too, those threads are very interesting (though I regret they exist at all, very sad) and I am impressed by the collective knowledge.

However, having followed all aviation threads and more recently the AF447 threads, the malaysian airlines flight, the "head fake A380" fight thing and this, it's kinda interesting to me from a somewhat impartial distance how the "if it ain't boeing I ain't going" crowd is playing defense this time around, when Boeing is most likely going to be called for the exact same thing that Airbus has been panned for on these pages (computers taking over, based on erroneous sensor readings or not, software fix making up from a questionable design change, not enough training for pilots to override computers, etc)... Hmm...
Kinda silly of the FAA not to ground the plane too (though I understand there needs to be an "ungrounding" criteria and it's hard to see what that will be yet) but travellers are voting with their feet big time at the moment, so they might as well.

I wasn’t saying that they were intentionally using fake parts, as the dirtbags in Third World countries will do, I was saying that it’s becoming more difficult to keep them out of the supply chain. It does happen.

https://www.washingtonexaminer.com/chinese-counterfeit-parts-found-on-raytheon-boeing-systems

March 12, 2019
Mitt Romney joins Democrats urging FAA to ground Boeing's 737-8 MAX
https://www.washingtonexaminer.com/business/mitt-romney-joins-democrats-urging-faa-to-ground-boeings-737-8-max

I did not realize this got into the political mainstream.

The vultures are circling.

Justt announced that the US is grounding them immediately

Apparently, Trump ordered the grounding. This is O level, "I'll stop the oceans from rising" idiocy.

Again, I have been the President of two military aircraft accident boards: data, not speculation is king....and I grounded the entire USMC CH-53E fleet based on data, not what I think happened. The Marines were pissed but we were right, which they acknowledged when the dust settled.

How many flight hours on the 737 Max between the two accidents - pilot reports, MAFs, etc.?

What a world.

Once Canada buckled we didn't have much choice.

Grounding an aircraft type should not be decided by the President or any politician. It should be a FAA technical decision.

I've not gotten involved in the debate here about cause etc. I have my opinions but no relevant expertise/data so best to stay quiet.

BA looks v interesting here, though.

^^^ But our president has the most bigly ...... bestest ....... stable genius brain there is and probably knows more than the Boeing engineers :rolleyes: Sorry couldn't resist . I do agree this is not a political issue , the data/facts have to be gathered by the experts . That data has to be analyzed to come up with the likely cause of these two crashes . At this point NO ONE knows what the cause is or if they are similar causes . RIP to all that lost their lives and to their surviving loved ones .

Yup. Sadly when aerospace incidents bubble into the public eye they quickly cease to be rational data-driven discussions and immediately become emotional and irrational. Political affiliation aside, watching our political leaders fumble to even describe why the airplane should be grounded was painful.

Is Trump's involvement unprecedented?

I agree this should be an FAA decision.

Is one of the short comings of a "point to point" air traffic system where soft hubs are possibly denying aircraft full and proper servicing and by using second tier pilots (in foreign countries) a factor?

Western Europe because of population densities and limited land is projected to remain Hub & Spoke, while growth markets such as Africa and Asia (5-6 percent growth annually) and the North America (lower projected growth) will be going to "point to point" in the next decade. Hence economy airlines like Southwestern's use of the 737 Max in less popular routes with smaller aircraft.

Boeing 737 Max: How many of those planes fly for Southwest, American, United, and where?
https://www.usatoday.com/story/travel/flights/2019/03/12/boeing-737-max-how-many-fly-southwest-america-united-and-where/3143113002/

Air route maps and aircraft count in link above.

I'm just saying that the more out of the way places that use high technology aircraft, the more one would expect to see these type of events playing out over and over again - sadly.

Interesting article.

Regarding the bolded above:

Agree, and it appears to not even be a question on this latest crash, IMO. The FO on that A/C is reported to have +/- 200 hours TOTAL. If that's true, it is rather scary.
You would not be allowed to fly right seat (SIC/FO) of any commercial airline in the US with only 200 hrs. That is WAY below even the lowest "restricted" ATP requirements.

I agree it should have been a data driven decision and not political...but what the #$%$ was the FAA waiting for ?

That specific airplane is a very small % of the overall jetliner fleet, is it such a terrible thing to err on the side of safety, instead of waiting for a non-third-world flown one to crash to prove or disprove it was pilot error/insufficient training? Money vs lives... Would you have sent your family on one ?

BA dropped 3-4% intraday on news of Trump ban, immediately recovered to close flat, investors are betting this will be resolved soonish w/o signif consequence to the company.

"Boeing continues to have full confidence in the safety of the 737 Max. However, after consultation with the US Federal Aviation Administration (FAA), the US National Transportation Safety Board (NTSB), and aviation authorities and its customers around the world, Boeing has determined -- out of an abundance of caution and in order to reassure the flying public of the aircraft's safety -- to recommend to the FAA the temporary suspension of operations of the entire global fleet of 371 737 Max aircraft."

I guess that clarifies who wears the pants in that relationship...

To say it shouldn’t be a political decision is just naive. Sorry, it’s not a perfect world. Imagine if God-Forbid another one crashed in the US and DT didnt take a stand. Think it would be political then? I believe the “F” in FAA stands for federal. It’s just the world we live in. He did what he had to do.

[QUOTE=Deschodt;10389433Money vs lives...Would you have sent your family on one ?[/QUOTE]

Sure. Today. I'd get a cramp typing why.

Aviation accidents are spectacular events in lives lost and fear of the next flight.

When you ground an aircraft, there has to be a reason and a path to get the aircraft back in the air.

They had a reason. Two have dropped. The US was the only one left flying. There is a problem somewhere within the process.

When Canada grounded them they had no choice.

Ok. I am all for it; But tell me why you would ground the fleet?

Pilot error?

System error?

Maintenance?

Fundamentally flawed aerodynamics?

Fire?

Terrorism?

Then tell me how we get them back in the air. What is that path forward and based on what data?

Of course you know the answer, I'm right with you. You also know the one that made the decision isnt the least bit interested in fact, reason or logical problem solving. CYA and maybe some air time. Sad state when such a decision has such an impact on so many.

I only hope the smart folks looking at this have everything they need and come to a quick determination of the actual cause(s).

I have question about being able to recover control. This jet has a gross takeoff weight of about 194,000 ibs. In an episode like what has now occured twice, is a competent pilot able to get it back under stable flight when this close to the ground? Jets are extremely slippery aerodynamically and once established in oscillations of rapid up and down and being so heavy it seems like you could use up a lot of sky getting it back. What about a flat spin?
Ethiopian Airline said the pilots had had extra instruction on this issue in these variants and if a very experienced 8000 hour ATP couldn't get it done, what then? Once this problem starts, can it be brought back under control? It's not like being in cruise at 30,000' with 5 miles of sky below to play in.

They don't need to know actual cause to ground them. If one was dropping out of they sky each week would we let them keep flying? Hell, no.

It happens all of the time. When Blue Bell recalled their ice cream they had no idea of root cause. They shut down for months to find the source.

When Firestone had their massive recall due to tread adhesion they had no idea of the root cause.

It looks like the 737 has about 2% of total US flights (USA Today). That amount grounded won't kill the industry. Another downed plane, though very unlikely, would kill Boeing.

They are doing the correct thing.

Absolutely - unfettered by politics.

As a former pilot, connected to my flight control surfaces by push-rods, bell cranks, hydraulics and mechanical oomph, I have a certain nostalgia for pilot in the loop systems.

Those days are over (and I am glad I survived them) - I bet the simulators are working 24/7 with all ranges of pilots trained to fly the Max, from Sully to Dully.