WaterDamage

LOL physics is pretty much the same as it was 20 years ago. When things don't fit and the basic aerodynamics are impacted, time won't change that. You talk about airframe changes but that's exactly that point - we are talking about (supposedly) the same airframe - so changes are very limited. As for things 'that weren't being considered back then' there is nothing on the max that wasn't being considered back then - it takes a long time to develop engines and aireframes.

And to answer your question, yes I'm intimately familiar with the technology advancement over the period of time we are talking about and it's at best incremental. The vast majority of the performance improvement is in being able to run a larger diameter, lower pressure ratio fan. Thrust-specific fuel consumption is a function of both thermal efficiency and propulsive efficiency. With only modest gains in thermal efficiency, the propulsive efficiency (larger fan) is the big knob to turn.

Finally, yes it was the right choice to abandon the large-diameter fan concept back then. As an engineer you should never fall in love with your own ideas.

TonyStark

WaterDamage Thanks for your perspective.... We are aligned in position...
SWA737 Respectfully, I disagree with your assessment...Further, I think it's a bit negligent to be so flip about it.

Now, I've previously posted my position on this issue earlier...

Fast forward to today and I'm in a park watching dolphins play, and a older couple comes over and we strike up a conversation. We talked about the weather, vacations, etc, and he mentions working in Wichita Kansas, so immediately I pick up that he might have an aviation background. I ask if it was for Cessna and he confirmed it...We discussed a bit about his time there and also his time at Boeing... Both, as a structural engineer, if I understood correctly....So now I have no option but to bring up the MCAS and ask his thoughts.

So here is an aeronautical, structural engineer, giving me confirmation bias on all the issues that concerned me. Basically, his words could have come out of my mouth.... He was there...I really think Boeing is making a huge mistake trying to get this embarrassment certified.

I was a "Boeing or not going" type of guy. Further, I believe Boeing is literally too important to the US and national security to fail. So I don't wish anything bad on Boeing. But I do strongly believe management should be changed at Boeing and the FAA and the MAX should be over. The MCAS is a fail...We do not need civilian planes inherently unstable...

Classic25

If you don't mind me asking, how are you affiliated with the B737, as your interest level with the MAX seems to be extremely high.?

Classic25

Q. How do you know when there's a pilot in the room?
A. He'll tell you.

SWA737 has a long history with the 737 that he can share from the pointy end. He brings the pilots perspective, and does that very well. But, you have to remember, it's a pilots perspective.

mikeloew

Thinking maybe Boeing should keep the letter X out of any of their aircraft. Here is a pic of the 777X failure. But I guess that's what extreme tests of its structural strength is meant for. Better now than later.

Dime

And who do you think would have a better idea about it than those of us who fly it?

TripleCrownNC

Right, and the thing that jumps out at me is the pilots in the lost planes didn't follow standard procedures due to a lack of training, and if you believe swa 737, those planes could have been landed safely.

GulfC

The ones that work on em’.

Dime

Because their ass is on the line as much as ours?

Please.

In fact, wasn’t the Lion Air aircraft suffering the same exact problem the day prior and was written up, only to crash a day later?

km1125

Not only was written up, but that very plane was landed safely even though the same faulty AOA sensor acted up and caused MCAS to respond. The pilots were able to land the plane only because there was a 'guest' pilot on board who reminded them how to respond to an uncommanded trim activation, and they then followed the procedures correctly and landed the plane.

Dime

Dammit! That was my best swimming ballyhoo too!

Can't fight emotion with logic these days, can you?

WaterDamage

MCAS documentation was omitted at Boeing's request during cert because Boeing argued there was so little chance it would ever be activated. Clearly that was 100% BS - then MCAS activation envelope was expanded after FAA agreed to this - they should have been notified but were not, and the recent text messages from the chief test pilot prove this. I respect the pilots on here saying they should be able to catch this in-flight, but from an design engineering standpoint we should never be putting pilots in the situation where undocumented flight control software erroneously pitches the aircraft down, especially based on a single instrument. That's so far out of the box of aerospace design safety standards it's ridiculous. To argue against it is to argue against design margins, system redundancy, and general aircraft safety requirements.

johnny.dollar

It is terrible engineering to rely on the skill of a pilot to correct a design flaw. Planes need to be designed for the average/below average pilot. If only the top notch and best trained can safely fly it, the design is a failure.

Competent pilots should be able to land with the trim runaway by following proper procedures. But, the trim runaway should not have occurred in the first place.

Very few pilots are engineers. And many (or most) engineers would make poor pilots.

GulfC

They are all designed as such .... apparently till the max came along. https://en.wikipedia.org/wiki/Fail-safe

km1125

I agree with all of that. They definitely could have done better with the deployment and training, but none of that makes the whole plane inherently "bad" or a bad design. Could definitely be tweaked to be better and I'm sure they'll do that before it's re-released into the air.

The planes don't have to get much better before the pilot is eliminated completely from the loop. I'd still like to have them up there though, but they'll actually have to be BETTER if they're going to do any good, just like the pilots today should be better than the ones 20 years ago.

BTW, they don't document all possible electrical failures in a plane and train all pilots on how to deal with them, BUT they do put a variety of systems in place (like "cut off" switches) that will handle a wide variety of failure problems with a simple solution.... activate the "cut off" switches and you eliminate the problem, no matter what the cause. Because the cause can be from hundreds of different things.

20biminitwist

I have followed this thread from the start.
How many successful flights have these planes had.
How many of these planes crashed with well trained pilots?
How many well trained pilots refused to fly this plane?
How many times was this scenario avoided by well trained pilots?..
Is the condition that causes the crash not correctable from the cockpit by a well trained pilot ?
Maybe there is more to this but it seems that the problem has been identified. I really can't grasp that they can not seem to design a fail safe to get these planes back in the air.

I am a dummy to all this and have enjoyed a lot of the input from both the pilots and engineers on here but it sure seems like the search for who to blame is bigger than the search for a resolution to the problem.

TonyStark

Respectfully, your questions aren't specific enough. You need to ask how many

How many successful flights have these planes had when an AOA sensors failed?

Just because a pilot successfully adverts a disaster doesn't mean there should have been a failure from the start.

In boaters terms, if you can successfully get your boat to a lift before it sinks doesn't mean the manufacturer should have only secured a thru-hull with double-sided tape.
It also my understanding that the switch to deactivate the MCAS is actually potentially behind the line of sight between the seats and aft of the flight controls. So if you're in a high stress situation and looking for answers, you aren't going to find it. Esp. if you didn't pay for the "should have been free" software upgrade that put a notice on the panel.

Corndog38

I too think the fix to the aircraft is pretty well understood and should be pretty quick. And that pilot error was a large factor in the two crashes.

I don't think it is simply looking for someone to blame. The issue is that the certification process in both Boeing and FAA failed. This issue is "how did this get through??". Both organizations are going to revise how they design (Boeing) and certify (FAA). That of course could happen after these things get in the air. BUTTTT.. Now they are going through the entire aircraft and going through every system, every line of code, etc, and that takes time.

Oh, and the bureaucrats are in charge. They don't do anything quickly.

YFMF

I'm late to this topic, but I find it criminal that "A" they would charge an additional fee for a software upgrade and "B" that every airline in the world wouldn't pay for it and sue the builder in court.

Classic25

Acceptable certification.
You touched on a couple of things not really discussed in this thread.. Fail safe, which can be expanded to include fail passive and fail operational. All mean something a little different, and none of them can be used to describe MCAS.

--basically speaking-- (I know some heads will explode with this response)

The condition MCAS was designed to correct what a stick pusher or nudger is supposed to do when the airplane arrives at a condition of flight it wasn't supposed to be in (or at least mimic the behavior of previous models of 737's). Engineers and test pilots identified a specific flight characteristic that needed an aggressive response, historically performed by a stick pusher system. Instead of adding a stick pusher, they jury rigged the trim system to behave like a stick pusher. This is a unicorn in the commercial passenger airliner segment.

Steps could have been taken to make it fail safe, or fail passive. For a myriad of reasons they weren't.

Boeing is in virgin territory with this evolution of the 737 they brought to market. There's a lot of fingers in the pie now, that never were before. I'll be surprised if they're flying early next year.
https://www.faa.gov/news/media/attac...A_Oct_2019.pdf