B737MAX [Grounded as of 13 March 2019]

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United does not fly the 737 MAX 8 that has been involved in two recent crashes, but it does operate the 737 MAX 9.

How to tell if your flight is scheduled to be operated by the MAX 9:

View your reservation or flight status page, either on the web or on the app. United lists the entire aircraft type. Every flight that is scheduled to be on the 737 MAX will say "Boeing 737 MAX 9." If you see anything else -- for example, "Boeing 737-900," it is not scheduled to be a MAX at this time.

The same is true in search results and anywhere else on the United site.

For advanced users: UA uses the three letter IATA identifier 7M9 for the 737 MAX 9.

All 737 MAX aircraft worldwide (MAX 8, MAX 9, and MAX 10) are currently grounded.
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Old Mar 19, 19, 11:14 am
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Originally Posted by IADFlyer123 View Post
The blame here seems to be solely on Boeing's shoulders. They originally submitted FAA cert docs that mentioned the MCAS system could only manipulate the tail by 0.6 degrees. They then realized that 0.6 was not sufficient and decided to reprogram it allow for a 2.5 degree manipulation without letting the FAA know (atleast that is what the article implies).
If the article is correct, then it was much worse than what is mentioned above, as the system would reset itself each time there was a corrective pilot input, effectively allowing "endless" MCAS manipulation.
The proposed software update was/is to only allow a one-time automatic manipulation.
This, coupled with only one sensor being used for the MCAS evaluation and not both, and also not checking for sensor comparison errors pre-departure (Lio nAir sensors were apparently off by 20 degrees prior to take-off), tells me that there was some serious logic failures at Boeing.
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Old Mar 19, 19, 11:19 am
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Originally Posted by amtrakusa View Post
i wonder if there are similar systems in the new versions of A320? folks, there are bunch of things people don't know about. don't think Boeing is unique in any of these.
I was thinking about that also & saw some discussion that Airbus had redundant systems.
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Old Mar 19, 19, 11:24 am
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Originally Posted by bman1002 View Post
Not only that, but what about the 777X folding wingtips? Makes you wonder if the same (or any) care was taken to certify that. I don't believe United has any on order, but from my understanding, not all customers have been identified.

If it's a new Boeing, I'm not going.
I am not letting Boeing off the hook, but the certification process for the 777X should be very different than for the MAX, where Boeing tried to sneak an airplane with very different handling and systems under an existing certification. I assume Boeing will have to do a full training program to fly the 777X, if not, then that is a big problem IMHO.

Originally Posted by amtrakusa View Post
i wonder if there are similar systems in the new versions of A320? folks, there are bunch of things people don't know about. don't think Boeing is unique in any of these.
The neo program did not make any fundamental changes to the air-frame in the same way that Boeing did for the MAX. They basically just added new engines and did some clean up and weight reduction. The sharklets and some of the clean up was already on late model ceo models. My understanding is that the actual plane flies exactly like a sharklet (out since about 2010) equipped A320/321. The first round of changes (to the ceo, with sharklets) over time reduced the fuel burn by about 5%, then adding the new turbo-fan engines (making it the neo) allowed a further 10% reduction in fuel burn.

Boeing OTOH had to put new front landing gear, changed the tail, and moved the engines up and forward, all of which changes the aerodynamics and as such how the plane flies. The MCAS system was designed to mask these changes in how the plane flew. Airbus did not have to do something like this.

Originally Posted by IADFlyer123 View Post
The blame here seems to be solely on Boeing's shoulders. They originally submitted FAA cert docs that mentioned the MCAS system could only manipulate the tail by 0.6 degrees. They then realized that 0.6 was not sufficient and decided to reprogram it allow for a 2.5 degree manipulation without letting the FAA know (atleast that is what the article implies). So the FAA certified the plane on an assumption that MCAS would move the plane by +/- 0.6 degrees and in reality was doing +/- 2.5 degrees. That is half the total movement and in flight terms a lot! Yes the FAA didn't double check, but looks like Boeing manipulated - maybe just like VW did with the emissions scandals to fool the inspectors and the inspection.


Article Source - https://www.seattletimes.com/busines...ion-air-crash/
In fairness, I don't think that the FAA would have done anything different if told it was 2.5 degrees, given the degree of regulatory capture that Boeing has, but the lawyers (and congress) will have a field day with this.

What I think that this shows is how much different that the MAX is from the NG. They needed a full 2.5 degrees.
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Old Mar 19, 19, 11:32 am
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Originally Posted by narvik View Post
If the article is correct, then it was much worse than what is mentioned above, as the system would reset itself each time there was a corrective pilot input, effectively allowing "endless" MCAS manipulation.
The proposed software update was/is to only allow a one-time automatic manipulation.
I am surprised to hear that the software update will to allow only one-time activation. The change to two-channel fail-safe architecture and inhibition of the function with AOA or airspeed disagree is pretty elementary and should have been there from day 1. OTOH, if the MCAS function is limited to one cycle of nose-down trim input, it's much less useful as an active stall prevention feature and might be better served as an aural or tactile warning to pilots in the same vein as a horn or stick shaker.

Originally Posted by bman1002 View Post
I think it is also worth noting that the Seattle Times started their investigation on this issue prior to the second crash.
There is no shortage of disgruntled current and former Boeing employees in the Seattle area, so there's little doubt it would be easy to find anonymous sources and sufficient content for this investigative piece. There is a fair amount of uncertainty in the article, especially as it pertains to to the post-flight testing data, emphasis mine:

The former FAA safety engineer who worked on the MAX certification, and a former Boeing flight controls engineer who worked on the MAX as an authorized representative of the FAA, both said that such safety analyses are required to be updated to reflect the most accurate aircraft information following flight tests.

“The numbers should match whatever design was tested and fielded,” said the former FAA engineer.

But both said that sometimes agreements were made to update documents only at some later date.

“It’s possible the latest numbers wouldn’t be in there, as long as it was reviewed and they concluded the differences wouldn’t change the conclusions or the severity of the hazard assessment,” said the former Boeing flight controls engineer.

If the final safety analysis document was updated in parts, it certainly still contained the 0.6 limit in some places and the update was not widely communicated within the FAA technical evaluation team.
Nobody to date has actually seen what was submitted, with certainty, and can point to a smoking gun. If it's out there, rest assured it will be located.

With that said, the article hits on the lack of redundancy we have been discussing for nearly a week:

Lemme said Boeing could have designed the system to compare the readings from the two vanes, which would have indicated if one of them was way off.

Alternatively, the system could have been designed to check that the angle-of-attack reading was accurate while the plane was taxiing on the ground before takeoff, when the angle of attack should read zero.

“They could have designed a two-channel system. Or they could have tested the value of angle of attack on the ground,” said Lemme. “I don’t know why they didn’t.”
This, IMO, is the biggest problem for Boeing. There is a reasonable alternative design that would not have been prohibitively expensive to implement, and for whatever reason, it wasn't.
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Old Mar 19, 19, 11:36 am
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Originally Posted by clubord View Post
Respectfully, skill and judgement of pilots is gained from experience. A 200 hour pilot can just as easily put an Airbus in the trees as a Boeing.

I started my career in a CRJ with around 700 flight hours. Looking back now, that was dangerous. 200 hours is unimaginable in a B737, you're just a warm body working the radios with that experience level.
In almost every other country in the world (including Europe), it is completely normal for FOs to start flying after 150 hours or so of flying time. This ET FO who had 350 hours of flying time was no doubt inexperienced, but it is the norm in most countries and OEMs need to design aircraft and training keeping this fact in mind.

Most countries don't have general aviation like the US does, so pilot training is prohibitively expensive and difficult. Airlines usually pay for training for pilots with no experience (cadet system). It is not realistic to expect the airline to pay for 1000+ hours of flight training before getting their pilots on the line. The overall safety record of aviation worldwide seems to show that this system works reasonably well.
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Old Mar 19, 19, 1:13 pm
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Originally Posted by EWR764 View Post
I am surprised to hear that the software update will to allow only one-time activation. The change to two-channel fail-safe architecture and inhibition of the function with AOA or airspeed disagree is pretty elementary and should have been there from day 1. OTOH, if the MCAS function is limited to one cycle of nose-down trim input, it's much less useful as an active stall prevention feature and might be better served as an aural or tactile warning to pilots in the same vein as a horn or stick shaker.
Aye, I agree from a pure logical viewpoint.
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Old Mar 19, 19, 1:17 pm
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Originally Posted by PVDtoDEL View Post
In almost every other country in the world (including Europe), it is completely normal for FOs to start flying after 150 hours or so of flying time. This ET FO who had 350 hours of flying time was no doubt inexperienced, but it is the norm in most countries and OEMs need to design aircraft and training keeping this fact in mind.

Most countries don't have general aviation like the US does, so pilot training is prohibitively expensive and difficult. Airlines usually pay for training for pilots with no experience (cadet system). It is not realistic to expect the airline to pay for 1000+ hours of flight training before getting their pilots on the line. The overall safety record of aviation worldwide seems to show that this system works reasonably well.
Wasn’t it the Colgan Air crash (to bring some UA/CO back into the discussion) that changed the rules in the US for FOs minimum experience? Wasn’t it 250 hrs prior to that crash?
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Old Mar 19, 19, 1:22 pm
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Originally Posted by notquiteaff View Post
Wasn’t it the Colgan Air crash (to bring some UA/CO back into the discussion) that changed the rules in the US for FOs minimum experience? Wasn’t it 250 hrs prior to that crash?
Prior to the Colgan crash the FO could be a commercial pilot. Following the legislature that passed, FOs are now required to be ATP certified. This was a very poor, reactive, and short-sighted move.
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Old Mar 19, 19, 1:47 pm
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Originally Posted by PVDtoDEL View Post
In almost every other country in the world (including Europe), it is completely normal for FOs to start flying after 150 hours or so of flying time. This ET FO who had 350 hours of flying time was no doubt inexperienced, but it is the norm in most countries and OEMs need to design aircraft and training keeping this fact in mind.

Most countries don't have general aviation like the US does, so pilot training is prohibitively expensive and difficult. Airlines usually pay for training for pilots with no experience (cadet system). It is not realistic to expect the airline to pay for 1000+ hours of flight training before getting their pilots on the line. The overall safety record of aviation worldwide seems to show that this system works reasonably well.
In addition, I think it is important to note the pilot had 8,000 flight hours with 1,500 as a pilot. It is not like it was just the FO flying by himself. How do you expect FOs to get flight hours. I personally would have thought that would be flying with an experienced pilot....
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Old Mar 19, 19, 1:51 pm
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Originally Posted by cmd320 View Post
Prior to the Colgan crash the FO could be a commercial pilot. Following the legislature that passed, FOs are now required to be ATP certified. This was a very poor, reactive, and short-sighted move.
And what about a situation where the FO needs to take command of the aircraft and perform to ATP standards?
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Old Mar 19, 19, 1:59 pm
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Originally Posted by TomMM View Post


And what about a situation where the FO needs to take command of the aircraft and perform to ATP standards?

A FO under previous rule, which permitted a FO to have a CPL (250 hours), still meant the pilot would undergo training with the airline in systems and maneuvers, and would serve in that capacity (not an aircraft commander) until reaching the 1,500h threshold for an ATP, which did not change. Now, in order to serve as a FO for a US Part 121 carrier, an ATP is required. So it's not an issue of type- or operator-specific training, but rather overall experience.

The rule is controversial, but as a general matter it is premised on the theory that more hours = more experience = better/safer pilot. Importantly, it's not to say that 1500 hours = safe pilot, or 1500 hours = well-trained pilot, but there is no doubt that an ATP must demonstrate a higher degree of proficiency to earn the ticket.
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Old Mar 19, 19, 2:25 pm
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Originally Posted by n198ua View Post
I don't understand then - how have two planes flown themselves into the ground ? Certainly the pilots are trying - in vain - to pull the nose up with all they've got ? I can only speak for myself, but I'm imagining fight-for-life scenario in the cockpit with the flying pilots desperately trying to fly a plane intent on flying itself into the Earth ?
To answer that would be pure speculation until we have the reports from the accident investigation authorities.
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Old Mar 19, 19, 2:26 pm
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Originally Posted by TomMM View Post
And what about a situation where the FO needs to take command of the aircraft and perform to ATP standards?
The FO would still be trained and type-rated on the aircraft and perfectly capable of operating it safely.
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Old Mar 19, 19, 2:58 pm
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Originally Posted by EWR764 View Post
...This, IMO, is the biggest problem for Boeing. There is a reasonable alternative design that would not have been prohibitively expensive to implement, and for whatever reason, it wasn't.
Disagree with you here. The engineering mistakes and decisions will look bad, but are not the worst.

The worst was the decision to downplay the existence of the system. Had pilots been trained to recognize the failure they would not have spent precious minutes making useless trim adjustments that the MCAS would revers shortly afterwards. Cuting the electiic trim control completley and mechanically wheeling it in would presumably have worked in both cases.

So Boeing made a human decision to conceal that the MAX was more difficult to handle, and that decision cost lives.

The public can understand an issue like that a lot better than they can understand the concept of giving too much authority to the automated systems.

And at the end of the day, the public really does matter.
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Old Mar 19, 19, 3:19 pm
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Originally Posted by exwannabe View Post
The worst was the decision to downplay the existence of the system. Had pilots been trained to recognize the failure they would not have spent precious minutes making useless trim adjustments that the MCAS would revers shortly afterwards. Cuting the electiic trim control completley and mechanically wheeling it in would presumably have worked in both cases.

So Boeing made a human decision to conceal that the MAX was more difficult to handle, and that decision cost lives.
Which the runaway pitch trim procedure addresses, MCAS or not. As the actual pilots upthread said, they're more informed about MCAS now, but it's irrelevant to their reaction, they're still going to do the runway pitch trim procedure.

We don't know what cost lives yet, since the accident reports aren't out yet.
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