Boeing 737 MAX

[Baker]

Just another ignorant non-pilot question:

So the trim wheels are mechanically attached to the trim jackscrew mechanism? If the stab was in the nose down position per the crash AC, how many turns would it take of the wheels to get it to a normal position?

And it sounds like at their airspeed the aero loads may have prevented that motion? With elevators held nose up the handwheel would have to counter the loads from the elevators (since they are on the back of the stab)?

Yes the trim wheels are mechanically connected to the stabilizer. It would take maybe 5ish??? I don't know honestly. I have never counted. Interestingly, they limit the electric trim to 2 units....if you want to go full down, you have to go manually beyond 2 units. The electric trim will trim FROM zero all the way back up.

Yes, I am under the impression that it is difficult to turn when it is under heavy aerodynamic loads...which was the case here. We just don't use manual trim very often.

 

[twistedtree]

One other question - at least for now... I was surprised to read that the pilot was 29 years old, and the first officer 25 years old. That seems awfully young. Yes, no? I imagine it varies by carrier and by country.

 

[Wxx3]

That is easy to say after the fact. We have the benefit of hindsight and now knowing all of the subtleties of MCAS. They were faced with a lot of data to process and problems to solve. The stick shaker...erroneous airpseed...numerous caution lights...etc. Then add MCAS into the mix.

There have been airliners that have crashed with erroneous airspeed alone. Google Birgenair 301. They just had erroneous airspeed without all of the other crap and they still managed to crash it.

These guys were dealt a very bad hand.

RIP

Two things:
1. That Boeing has now delayed the promised fix for another month, that they have been on since Lion Air, but more significantly told the FAA that it would be given to them April 2nd. This tells me that they have found other MCAS reactions that they, whoever wrote this program, did not expect.

2. In my world travels and dealing with immigrant families in NYC, in spite of what impression you get from the press, most foreigners look up to the USA and think we actually know what we are doing.
So, it doesn't surprise me at all, that AA and SW took the optional warning display, while foreign airlines did not. I'm sure they felt that if Boeing thought they needed it, they would have it.
AA and SW knew better.

 

[BruceP]

This is an interesting discussion from a safety systems analysis site.

https://drive.google.com/file/d/1249KS8xtIDKb5SxgpeFI6AD-PSC6nFA5/edit

 

[ssobol]

I think it is something like 265 turns of the manual stab trim wheel to go from on end to the other.

 

[LN-RTP]

. I'm sure they felt that if Boeing thought they needed it, they would have it.
AA and SW knew better.

Nah, Boeing did not think they needed the optional AoA display in the cockpit.
More like: Well we are buying hundreds of these jets and Boeing said we get a big
Discount on the options so why not, it could be useful in a dark and stormy night when everything goes to poop.
List price for the AoA indicator was probably $80k,
a lot less for big customers like AA and SWA.
Some third world airlines may not appreciate that little gauge, or know how to use it.

 

[BruceK]

....These guys were dealt a very bad hand.

Baker, I think that nails it.
For those seeking to attribute responsibility to pilots and suggest in what seems a ridiculing tone that airline operators and pilots outside USA are inferior and less competent,perhaps as a way of loyally defending Boeing`s position perhaps not,I say please be fair. The genesis of the 2 crashes is an errant aircraft putting the pilots into an appalling position.
We all hope to be calm careful and methodical at all times,but please remember the saying "When you`re up to your ass in alligators it`s hard to remember the reason you got into the water was to drain the swamp".
True there have been outstanding pilot saves, the Sully river landing in NYC,the BA dive restart save after all 4 engines failed in a volcanic cloud,the Qantas A380 landing with an on fire engine post implosion with numerous systems crippled by shrapnel damage.
It`s likely these pilots did their best in a horrible situation, but the investigations will resolve all of that.
That it is taking Boeing months to rewrite programming even under the pressure of grounded aircraft suggests to me there is a good deal of programming which can benefit from improvement.

 

[LN-RTP]

. For those seeking to attribute responsibility to pilots

Pilots are responsible for the safety of the flight.
I don’t think all these people deserved to die as the airplane was indeed “flyable”: A stick shaker going of in the cockpit was indeed a distraction, but they airplane as a whole was in good shape, both engines turning, both wings attached, etc.
The MCAS system did not do them any favors, but it can be turned off by extending flaps or flipping 2 Stab Cutout switches to off.
What ruined the day for these people was the pilots forgetting to dial the speed back: They left the throttles at a high power setting until the airplane became in-controllable, sadly.

 

[Brisyboy]

Baker, I think that nails it.
For those seeking to attribute responsibility to pilots and suggest in what seems a ridiculing tone that airline operators and pilots outside USA are inferior and less competent,perhaps as a way of loyally defending Boeing`s position perhaps not,I say please be fair. The genesis of the 2 crashes is an errant aircraft putting the pilots into an appalling position.
We all hope to be calm careful and methodical at all times,but please remember the saying "When you`re up to your ass in alligators it`s hard to remember the reason you got into the water was to drain the swamp".
True there have been outstanding pilot saves, the Sully river landing in NYC,the BA dive restart save after all 4 engines failed in a volcanic cloud,the Qantas A380 landing with an on fire engine post implosion with numerous systems crippled by shrapnel damage.
It`s likely these pilots did their best in a horrible situation, but the investigations will resolve all of that.
That it is taking Boeing months to rewrite programming even under the pressure of grounded aircraft suggests to me there is a good deal of programming which can benefit from improvement.

Of course the follow on from this Bruce, is that it might have been a 3rd world airline, but chances are the pilots were trained in a 1st world country - perhaps even the US.

 

[LN-RTP]

Of course the follow on from this Bruce, is that it might have been a 3rd world airline, but chances are the pilots were trained in a 1st world country - perhaps even the US.

Ethiopian Airlines have their own Flight Academy and it appears that both pilots were trained right there.
As for 3rd world airline: Accidents happens all over, not too long ago a Southwest Captain landed on the nose wheel and wrecked the airplane right here in the good old USA.

 

[Ski in NC]

I think it is something like 265 turns of the manual stab trim wheel to go from on end to the other.

Sounds like it would have taken a lot of turns of the wheel to bring AC back into trim. Not 265 as it did not need to go from stop-to-stop, but even if it took 50 turns, they simply did not have time for that. If they could even turn the wheel due to aero loading.

So with the controls in the accident conditions, was the jackscrew motor totally disabled?

Could the MCAS been disabled yet still have control of the jackscrew motor?

 

[twistedtree]

What ruined the day for these people was the pilots forgetting to dial the speed back: They left the throttles at a high power setting until the airplane became in-controllable, sadly.

So for our 737 pilots, does this sound correct? That the pilots were doing, and did all the right things to recover, but neglected to throttle back?

 

[LN-RTP]

So for our 737 pilots, does this sound correct? That the pilots were doing, and did all the right things to recover, but neglected to throttle back?

Based on the preliminary report, they did not do all the right things to recover, but rather a series of errors: Selecting Flaps UP, trying to select auto pilot on, not flying pitch and power, no speed control, etc, etc.
(I know, easy to sit back and criticize dead men with the benefit of hindsight but this flight could have been saved)

 

[sunchaser]

LN
Assuming your seat experience covers 737, have you flown the Maxx? What do the common US carriers have for "key" Maxx control training that differs from the non Maxx 737s.

Appreciate your experienced comments.

 

[LN-RTP]

LN
Assuming your seat experience covers 737, have you flown the Maxx? What do the common US carriers have for "key" Maxx control training that differs from the non Maxx 737s.

Appreciate your experienced comments.

I have flown a 737 and a bunch of other Boeing’s.
The differences on the MAX are taught as a supplemental lesson on an iPad in many cases, or a PowerPoint presentation.
No separate MAX simulator needed as differences are relatively minor.
This accident however was caused by a “generic” problem: A damaged AoA vane giving an erroneous airspeed indication causing a stall warning. (Stick shaker)
All of the above is the same on the max as on the regular plane 737 and on other Boeing’s. At that point you don’t raise the flaps, but these guys did, then it wen’t downhill from there. (MCAS only wakes up if you retract the flaps)

 

[Baker]

I have flown a 737 and a bunch of other Boeing’s.
The differences on the MAX are taught as a supplemental lesson on an iPad in many cases, or a PowerPoint presentation.
No separate MAX simulator needed as differences are relatively minor.
This accident however was caused by a “generic” problem: A damaged AoA vane giving an erroneous airspeed indication causing a stall warning. (Stick shaker)
All of the above is the same on the max as on the regular plane 737 and on other Boeing’s. At that point you don’t raise the flaps, but these guys did, then it wen’t downhill from there. (MCAS only wakes up if you retract the flaps)

Again....you are using your knowledge of MCAS with hindsight. All of the information on MCAS was not fully known or understood. "Leave the flaps down so MCAS does not intervene"...we didn't know all of that. I could respond with "turn the autopilot on so MCAS doesn't intervene" based on your reasoning(actually a contradiction to your reasoning). You would have arrived at your "flyable airplane" strictly by accident....or luck. WHat most pilots DO know is that if one stick shaker is activated, then it is a system malfunction. If both are activated, it is a stall. THis guy may have solved that problem and noticed their speed increasing so he raised the flaps so he would not overspeed them. I am just speculating and giving a reason of why he raised the flaps. Yes, they never moved the thrust levers. Definitely hard to imagine a windshield full of Earth and not retarding the power.

One question that has not been addressed.....what in the hell was going on with the airspeed indication??? Airspeed indication, as far as I know, has absolutely nothing to do with AOA vane...maybe I'm wrong. But that is a separate (multiple) failure.

And finally, it was not an AOA indicator that was the option(although it is). It is the second input to the MCAS computer that allows MCAS a "comparator" to check the "reasonability" of its indication and a light that illuminates if they disagree. That WILL be one of the fixes and it WILL disable the new version of MCAS if there is a fault with the input data. A simple AOA indicator probably would not have helped....althoug it is also an option.

 

[LN-RTP]

. Again....you are using your knowledge of MCAS with hindsight. All of the information on MCAS was not fully known or understood. "Leave the flaps down so MCAS does not intervene"...we didn't know all of that.

Of course it is hindsight, we are all discussing an accident that already happened.
After the Lion Air accident I would think all 737-MAX crews should have been briefed on the MCAS system and that Boeing and the Operators sent out bulletins with all the details, are you saying they did not and MCAS was still a mystery when the Ethiopian MAX crashed?

I could respond with "turn the autopilot on so MCAS doesn't intervene" based on your reasoning(actually a contradiction to your reasoning).

As you know, not a good idea to turn the autopilot on with unreliable airspeed and stick shaker going on, but you knew that?

Listen carefully: I am not out to hang the crew or blow sunshine on Boeing, my agenda is that 157 people died that day, yet they could have lived if somebody did a better job of operating the airplane, either with flaps, airspeed control, whatever, but there was several ways of saving the day without having to be Chuck Yeager or Superman, really.

 

[Baker]

Of course it is hindsight, we are all discussing an accident that already happened.
After the Lion Air accident I would think all 737-MAX crews should have been briefed on the MCAS system and that Boeing and the Operators sent out bulletins with all the details, are you saying they did not and MCAS was still a mystery when the Ethiopian MAX crashed?

As you know, not a good idea to turn the autopilot on with unreliable airspeed and stick shaker going on, but you knew that?

Listen carefully: I am not out to hang the crew or blow sunshine on Boeing, my agenda is that 157 people died that day, yet they could have lived if somebody did a better job of operating the airplane, either with flaps, airspeed control, whatever, but there was several ways of saving the day without having to be Chuck Yeager or Superman, really.

Really the only thing emphasized after Lion Air was the use of the trim cutout switches and made it a memory item where before it was not. THey did NOT say....you might get a stick shaker activation...you might get unreliable airpseed...you might get a series of lights....the autopilot might kick off. So yeah, these guys should have hit the cutout swtiches sooner than they did. What I am getting from you is that this would not have happened to you. I am just saying I understand how it happened and that it was a difficult problem to solve....actually numerous problems to solve....along with a system trying to push the nose over.

Me personally, I would like to think I would have been all over that electric trim at the start of the situation....just instinctually getting the airplane to feel right. ANd because of that I would like to think I would have noticed MCAS trimming against me and hit the cutout switches. But I understand the rabbit holes they went down and I could see other crews doing the same thing...even American trained crews. Hopefully we will see this in simulator training soon!

 

[LN-RTP]

. What I am getting from you is that this would not have happened to you.

No, you are dead wrong, I never said I could do better, I said the plane could have been saved, this is not about me.

THey did NOT say....you might get a stick shaker activation...you might get unreliable airpseed...you might get a series of lights....the autopilot might kick off.

You could get all of that whether on a MAX or not, should Pilots these days be spoon fed any possible combination of scenarios or failures?
Maybe so, I am not sure, don’t have the answers and yes, I am sure it was confusing in the cockpit with bells and whistles going off giving erroneous information, but was it automatically a death sentence?
Seems we disagree there..?

 

[Baker]

but was it automatically a death sentence?
Seems we disagree there..?

Nope, we don't disagree there....like I said, I understand how it ended the way it did. And yes, I understand all of the symptoms of an AOA vane malfunction. Given the severity of the situation, a little spoon feeding would have helped a bit.

My experience(in case anyone was wondering)
3 years as 737 First Officer....approx 2000 hours
7 years as 757/767 FO....approx 4500 hours
7 years as 737(currently) approx 4500 hours
Type rated on all of the above as well as 6 other type ratings on various trasport category aircraft....approx 20,000 hours total.

 

[Seevee]

<<<<<Originally Posted by ssobol View Post
I think it is something like 265 turns of the manual stab trim wheel to go from on end to the other.>>>>>

Sounds like it would have taken a lot of turns of the wheel to bring AC back into trim. Not 265 as it did not need to go from stop-to-stop, but even if it took 50 turns, they simply did not have time for that. If they could even turn the wheel due to aero loading.

So with the controls in the accident conditions, was the jackscrew motor totally disabled?

Could the MCAS been disabled yet still have control of the jackscrew motor?

I believe, the number of turns was 7 or so, and believe Baker quoted that... doesn't he currently fly the NG model? When I flew the earlier 300 and 500 models of the 737 it was about the same, but really never had a reason to crank them to the limits.

 

[LN-RTP]

Nope, we don't disagree there....like I said, I understand how it ended the way it did. And yes, I understand all of the symptoms of an AOA vane malfunction. Given the severity of the situation, a little spoon feeding would have helped a bit.

My experience(in case anyone was wondering)
3 years as 737 First Officer....approx 2000 hours
7 years as 757/767 FO....approx 4500 hours
7 years as 737(currently) approx 4500 hours
Type rated on all of the above as well as 6 other type ratings on various trasport category aircraft....approx 20,000 hours total.

Roger on your experience, perhaps we work for the same company, I did the 757/767 thing as well.
I have 19 flying jobs under my belt, licenses from 4 different nations, worldwide long-haul, etc., etc. (All that and 50 cents won’t get me a cup of coffee right now, out on medical retirement, or Loss of License, doubt I am going back, burned out.)

With all your 737 experience, do you think the MAX should be grounded right now that we know a faulty angle of attack vane initiated the Ethiopian accident?

 

[Wxx3]

No, you are dead wrong, I never said I could do better, I said the plane could have been saved, this is not about me.



You could get all of that whether on a MAX or not, should Pilots these days be spoon fed any possible combination of scenarios or failures?
Maybe so, I am not sure, don’t have the answers and yes, I am sure it was confusing in the cockpit with bells and whistles going off giving erroneous information, but was it automatically a death sentence?
Seems we disagree there..?

So, LN, if the fix is so simple, why is Boeing taking half a year to fix it?
And that's even after the planes were grounded and they finally understood they had a real problem that evidently goes far beyond pilot training.

Again, it's significant that a week ago, they thought they had the problem solved, oops, it's not solved and they need at least another month.

What that tells me is that whatever entity cobbled together this million plus lines of programming maybe should have run it by a pilot at some point and not just someone who knew what was supposed to happen.

The month delay tells me that was is supposed to happen, doesn't always happen.

I think what's going to finally come out of this is that the computer was flying the plane in ways unanticipated by Boeing.

 

[Seevee]

<<<<
Originally Posted by LN-RTP View Post
What ruined the day for these people was the pilots forgetting to dial the speed back: They left the throttles at a high power setting until the airplane became in-controllable, sadly. >>>>>>>

So for our 737 pilots, does this sound correct? That the pilots were doing, and did all the right things to recover, but neglected to throttle back?

We just don't know. Perhaps in the confusion, they really thought they were going to stall and reluctant to pull the power back. They probably could have figured it out but maybe didn't have the time. Perhaps most pilots would have pulled the power back. Heck, I would have done that, and I would have put the gear down and probably full flaps, speed brakes, shut off the trim and manually trimmed back and put the plane in a 45d turn, when I realized that the speed was going out of control and the plane was headed for the ground.... but that's easy to say on Monday morning quarter backing.

 

[Seevee]

Pilots are responsible for the safety of the flight.
I don’t think all these people deserved to die as the airplane was indeed “flyable”: A stick shaker going of in the cockpit was indeed a distraction, but they airplane as a whole was in good shape, both engines turning, both wings attached, etc.
The MCAS system did not do them any favors, but it can be turned off by extending flaps or flipping 2 Stab Cutout switches to off.
What ruined the day for these people was the pilots forgetting to dial the speed back: They left the throttles at a high power setting until the airplane became in-controllable, sadly.

LN-RTP,

Of course the pilots are responsibility for the safety of the flight. So are the dispatchers, schedulers, management the aircraft builders, inspectors, mechanics AND the FAA.

The plane may or may not been flyable based of what the pilots knew and how they were trained.

One thing that has eaten on me a bit, its Boeings statement about the MCSS that the pilots don't need to know about it....too much information. Very unlike Boeing! My first training on a Boeing, I was taught to almost build the plane and could tell you what every buss operated, what the backups were, how to trouble shoot the pneumatics, hydraulics, etc., etc. Today's pilot is trained more to push buttons based on what lights come on.

So, if the pilots didn't know about it, how could they react to it's failure?

Sure, some smart pilot would figure it out, but we all aren't Sullys of Al Haynes.

Also, the 737 Max is NOT the first plane that has come with inadequate systems or pilot training..... there's tons of them. Look at the Airbus, and the original Lear 35 that lost 10% of their planes to control accidents..... and the MU2, Piper Cheyenne, and more. I've flown every one of those and can appreciate the differences in handling, unconventional systems, bandaids to fix a poor design and poor pilot training.

As for the single source AoA input.... I could argue that it would have been prudent to have a backup, but I don't believe those things fail often.... or at all. Of over 27K hours flying I've never had one fail, nor have I heard of one failing.

 

[Baker]

With all your 737 experience, do you think the MAX should be grounded right now that we know a faulty angle of attack vane initiated the Ethiopian accident?

Yeah I do. I would think it would be an easy/quick fix to provide two inputs and change the software to limit MCAS's authority.

I hope you get your health issues sorted out!!!

 

[Seevee]

Nope, we don't disagree there....like I said, I understand how it ended the way it did. And yes, I understand all of the symptoms of an AOA vane malfunction. Given the severity of the situation, a little spoon feeding would have helped a bit.

My experience(in case anyone was wondering)
3 years as 737 First Officer....approx 2000 hours
7 years as 757/767 FO....approx 4500 hours
7 years as 737(currently) approx 4500 hours
Type rated on all of the above as well as 6 other type ratings on various trasport category aircraft....approx 20,000 hours total.

Baker,

It's great to get your comments from someone currently on the plane..... love your posts! And spot on!

I retired from the airlines a few years back... miss the flying but not the BS. The 737 was one of my favorites. One of the best bids I had for a few years was a senior 737 captain on the old 737-200. I'd get my first choice and then trade trips for the easy stuff.... Day, VFR in sight of Chicago, fly out to podunk in the evening and be home in the morning with 2 days credit.

 

[LN-RTP]

. So, LN, if the fix is so simple, why is Boeing taking half a year to fix it?

Don’t think I said the fix was simple, Mr. Baker did:

.I would think it would be an easy/quick fix to provide two inputs and change the software to limit MCAS's authority.

No, I don’t speak for Boeing. In my opinion they should have built a modern medium airliner instead of trying to stretch and fix the old 737, but they never asked me.

The plane may or may not been flyable based of what the pilots knew and how they were trained.

If you are basing the “flyability” of the airplane on what the pilots knew, or how they were trained, it was obviously not flyable as they crashed into the ground at 500 knots.

Very unlike Boeing! My first training on a Boeing, I was taught to almost build the plane and could tell you what every buss operated, what the backups were, how to trouble shoot the pneumatics, hydraulics, etc., etc. Today's pilot is trained more to push buttons based on what lights come on.

Agree, I have been “building” a few planes in my life too: The worst one was my first jet: DC-8-73, FO seat, 1980 performance with 1950 technology.

Sure, some smart pilot would figure it out, but we all aren't Sullys of Al Haynes.

Agree, we can only hope we would do the right thing, but impossible to say in advance, hence I am a humble pilot, and I feel sad that the Lion Air pax/crew and the Ethiopian pax/crew had to die because of unreliable airspeed and runaway trim. Especially since the Lion Air MAX had the same problem on the previous flight, the crew did the right thing and they landed safely, reported it to Maintenance and supposedly it was “fixed” overnight. Think about that for a minute, they landed safely, but the next crew could not figure out the Stab cutout checklist and everybody died.
That Ladies and gentlemen is very sad, and even more so when it happens again 5 months later and big surprise again.
Yes, maybe Boeing should have emphasized it more, maybe the FAA should have empathized it more and the local authorities, their CAA or whatever they call them should have emphasized more, or all of the above.

I hope you get your health issues sorted out!!!

Actually my health is good, just a small technically that stops me from applying honestly for a 1st, Class Medical. (Some Guys lie and keep flying, I don’t lie and take a 65% pay cut, LTD)

 

[Baker]

No, I don’t speak for Boeing. In my opinion they should have built a modern medium airliner instead of trying to stretch and fix the old 737, but they never asked me.

I was just answering your question on whether I think the airplane should be grounded.

 

[Baker]

Baker,

It's great to get your comments from someone currently on the plane..... love your posts! And spot on!

I retired from the airlines a few years back... miss the flying but not the BS. The 737 was one of my favorites. One of the best bids I had for a few years was a senior 737 captain on the old 737-200. I'd get my first choice and then trade trips for the easy stuff.... Day, VFR in sight of Chicago, fly out to podunk in the evening and be home in the morning with 2 days credit.

Thanks for the kind words!!! And look forward to the retirement days. I am 53 and hopefully retire in 10 years or less. And I agree....lotsa BS that we put up with that most people don't know about.