Boeing 737 MAX

[AlaskaProf]

Maybe Boeing`s insurers had a hand in Boeing supporting the grounding. Past Comet and DC10 issues come to mind. I`m sure, given time, Boeing will remedy the situation.

Interesting point, although I wouldn''t be surprised if a firm with the value of Boeing "self-insures."


Boeing has been down this road before. Shortly after the introduction of the 727, there were three fatals involving that aircraft. I recall a lot of talk about people directing travel agents (remember those?!) to be sure they weren't booked on those airplanes.


Not unlike the present situation, eventually all were attributed to pilots--many transitioned from DC-6/7 technology who were "exploring" the airplanes' ability to descend like a fractured piano without fully understanding just how long it took to arrest with slow-reacting turbojets.

The aircraft crossed the outer marker over 2,000 fee& above the ILS glide slope. The rate of descent during the final approach exceeded 2,000 ft/min, approximately three times the United Air Lines recommended rate of descent for landing approaches. The first officer attempted to apply power but the captain stopped him. Power was then applied too late to arrest the rate of descent. The airplane touched down 335 feet short of the threshold of runway 34L.


The plane impacted with a vertical acceleration force of 14.7-g. ​

'Prof

 

[Delfin]

Maybe Boeing`s insurers had a hand in Boeing supporting the grounding. Past Comet and DC10 issues come to mind. I`m sure, given time, Boeing will remedy the situation.
Perhaps it`s a combination of design and pilots, but it would be a courtesy not to tip a bucket of excrement over the pilots pending clarification of the issue.I`m not inclined to accept,without more information, that a Captain with 8000 hours amassed that service time drinking coffee and on social media, while the planes flew themselves.

If the 8,000 hours were in that type of aircraft, yes. If not, then the hours, while not meaningless, are not by themselves going to familiarize the pilot with the new flight characteristics of a new type of aircraft.

 

[Moonstruck]

I know nothing about airplanes and flying, but a pilot friend sent this link to me. All I know about flying is the economy class seating is too dam small.

https://www.allkpop.com/forum/threa...r-any-mcas-software-controlled-planes.285900/

 

[BruceK]

...Boeing has been down this road before. Shortly after the introduction of the 727, there were three fatals involving that aircraft..Not unlike the present situation, eventually all were attributed to pilots..

You still anticipate blaming the pilots,before all information is available and assessed. Two planeloads of people have died, this is a really serious situation,and requires the most careful analysis.
The cause could be a combination of factors. For example:aircraft design/build defect,failure by the mfr to adequately flag changed characteristics,and pilot error. If it`s just the pilots, suspend them, not the aircraft, and train and qualify better pilots.
Your anticipatory presumption might be right.Or not. Presumption can set the "presumer" on a course of defending the presumption regardless.
Was the DC10 without fault?

 

[Screaming04]

Best article on the subject I’ve read.

https://nationalpost.com/news/heres-the-terrifying-reason-the-737-max-8-is-grounded

 

[AlaskaProf]

You still anticipate blaming the pilots,before all information is available and assessed.

[/quote}



Was the DC10 without fault?

On the contrary, I think this is much more likely to be a systemic failure and perhaps citing the SLC 727 event may have suggested otherwise. In that case, the captain's culpability was pretty specific, but even in his defense, seniority carried him from an old tech DC-6 captain's seat to a new tech captain's seat without the conditioning which would have come from learning the aircraft progressively from FE-FO-Captain. It is very telling that when the FO, who was the pilot-flying attempted to arrest the descent with power, the captain literally swatted his hand off the thrust levers.

The 200-hour Ethiopian copilot is not a villain, he is a victim. Similarly, I have no need to blame the 8000 hour captain who was confronted with an unexpected failure for which he was untrained and which his nation/company condemned him to correct without assistance.


I have less sympathy for the Lion air crew who lacked the simple human ingenuity to try the checklist procedure after 25 failures, but even they were put in those seats by a system that told them that they had the skills to operate this machine without giving them the authority to simply reject an aircraft which had a documented "no-go" system failure.


As for the DC-10, I confess that I never rode another after learning about the design deficiencies. I miss the Tristar.

But I have yet to hear anything suggesting that Boeing is guilty of anything other than selling 1st world technology to 3rd world organizations in the pursuit of profit., and that might be a long and wide-ranging argument indeed.


'Prof

 

[ssobol]

The engines on the 727 could take up to 8 seconds to spool up from idle to full power. A very long time if the ground is approaching quickly.

Even now, a lot of aircraft have flight idle speeds that are higher than the ground idle speed in order to reduce the spool up time if a go-around is suddenly necessary (including the 737).

One problem with the airline industry is the ingrained idea of the "seniority list". Unless you screw up badly or bust a couple of checkrides, your life is determined by your seniority number, not your ability as a pilot. As an airline pilot basically everything about your career is determined by when you joined the airline, not how good a pilot you are (as long as you meet the minimum requirements). Because Bob signed on 10 minutes before Joe, Bob will always get preference, promotion, etc. over Joe for everything job related unless Bob really f**ks up. It does not matter if Joe is a much better pilot than Bob, Bob always wins.

Thus a high seniority pilot good on the old stuff gets first dibs on flying the latest and greatest even though it may not be a good fit. Look at the senior captain who crashed the 777 at SFO because he could not hand fly an approach in a perfectly operating aircraft on a perfect flying day.

 

[AlaskaProf]

One problem with the airline industry is the ingrained idea of the "seniority list". Unless you screw up badly or bust a couple of checkrides, your life is determined by your seniority number, not your ability as a pilot. As an airline pilot basically everything about your career is determined by when you joined the airline, not how good a pilot you are

I once flew a training mission from the United Denver Training Center to qualify a captain on the 727.


The captain trainee was a superannuated flight engineer who had been coasting along for some decades, flying sideways and decided he needed to inflate his retirement annuity, so he had taken advantage of his very low seniority number to bid captain lines.



His airwork was very marginal, his systems work was good; coupled approaches etc. But he couldn't taxi the damm airplane to save his life. I left after 90 minutes, but it was clear that they would keep doing this until he met the minimum.

 

[Seevee]

According to the FAA it is the same plane as in 1968 when it first was certificated.

Would the FAA would issue a type certificate for a clean sheet design that has such undesirable flight characteristics as to need an MCAS to make it airworthy.? If not, why is this acceptable on yet another reworking of a 60 year old design?

The FAA has abrogated is responsibility to ensure safety by allowing Boeing to modify the 737 far beyond its type certification instead of forcing Boeing to pony up the scores of billions of dollars to recertify the newest modification as a new aircraft. Instead they have put the onus upon the flight crew and then decided to not even train them on their band-aid fix. They have also successfully shifted the discussion of responsibility from Boeing to to the pilots: this is so wrong on so many levels.

What the FAA does at times is hard to predict, however, I see nothing wrong with using the same type certificate. Has nothing to do with safety. But, any safety issue should be addressed regardless, and all of the differences and system changes well tested and noted. One can alter the original type certificate a lot before new certification is required. And one can add modifications that may change the flight characteristics, but needs to be tested, approved and a Supplemental Type Certificate issues.

As for the MCAS, I'm not a fan of bandaids to fix poor design, but there's a lot of them out there in the aviation world.

As for blaming the pilots, that's bordering on criminal.

 

[twistedtree]

I've been reading all this with great interest, and want to thank all the knowledgeable people who have contributed. As I said a while back, I know practically nothing about flying and planes, but have learned a ton here.


Most of the articles that have been linked are great examples of why I don't read or listen to the news anymore. It's just sensationalized garbage, loosely inspired by facts.


Based on what I've read, here's my understanding, and I would appreciate comment and correction...


- The design changes in the MAX changed it's flight characteristics, making it want to climb and potentially stall under some circumstances.


- To help compensate/guard against this being a problem, the auto trim system was enhanced to progressively nudge the nose down when a potential stall condition was detected.


- In all 737s trim is normally controlled by a thumb switching on the wheel/stick.


- If the thumb switches aren't working, or trim is not operating as expected for whatever reason, standard procedure is to disable the thumb trim control and use the manual wheel trim controls by the throttles. This has always been the case, and still is.



- If the MAX trim automation kicks in, whether correctly or erroneously due to a bad sensor, etc., it is immediately over-ridden by any pilot trim control on the thumb switches, and remains disabled for 10 seconds.


- The new trim automation is not described in the flight manual, so pilots are unaware of this new behavior. Regardless, procedures in the event of miss-operation are the same as they have always been - if you don't like trim, adjust with the thumb switches. And if that doesn't work, switch to manual trim with the wheels.



- Questions: This nudge-down trim automation is new, but is there other trim automation that has been in 737s previously? Or is trim all pilot controlled, either by the thumb switches or the wheel?


- Question: I also read somewhere about the stick providing a vibrating feedback to indicated something. What was that?

 

[FF]

" while not meaningless, are not by themselves going to familiarize the pilot with the new flight characteristics of a new type of aircraft."

The airframe builders always attempt to make the "new" version fly as close to the "old" version as they can.

This is pretty easy as the flight controls are computer driven, the pilot pulling on a yoke is pulling against bungee cords which is being measured to input the aircraft changes in direction.

Most companies today want the aircraft on autopilot as much of the flight time as can safely be done.
This allows best angle of climb or rate of climb and speed of climb to match ATC desires with least fuel burn.

"The captain trainee was a superannuated flight engineer who had been coasting along for some decades, flying sideways and decided he needed to inflate his retirement annuity, so he had taken advantage of his very low seniority number to bid captain lines."

The union seniority system allows individuals to select their home base ,aircraft choice , seat position and monthly sked that best suits them. Flight Engineers were only left on some few 747s perhaps he was bumped because the 747's were leaving?

Maximizing ones pension benefits before retirement would seem a rational choice.

"superannuated flight engineer who had been coasting along for some decades"

Guess you were a fighter pilot , they have the same contempt for co pilots and engineers , unneeded , as they can do it all, all alone.

 

[Seevee]

You still anticipate blaming the pilots,before all information is available and assessed. Two planeloads of people have died, this is a really serious situation,and requires the most careful analysis.
The cause could be a combination of factors. For example:aircraft design/build defect,failure by the mfr to adequately flag changed characteristics,and pilot error. If it`s just the pilots, suspend them, not the aircraft, and train and qualify better pilots.
Your anticipatory presumption might be right.Or not. Presumption can set the "presumer" on a course of defending the presumption regardless.
Was the DC10 without fault?

BruceK,

I could argue strongly against blaming the pilots. When you have two almost identical accidents with the same plane, it's unlikely that both captains slept thru the training session on auto trim.

 

[Seevee]

A look at a past problem,


https://imgur.com/a/5wcFx8M

Yes, brings back memories.... I flew the early 737s during that time, and yes, we did get training on how to control the plane with a hard over rudder. But our of 7000 hours in that plane, I fortunately never had to experience it.

 

[Seevee]

The engines on the 727 could take up to 8 seconds to spool up from idle to full power. A very long time if the ground is approaching quickly.

Even now, a lot of aircraft have flight idle speeds that are higher than the ground idle speed in order to reduce the spool up time if a go-around is suddenly necessary (including the 737).

One problem with the airline industry is the ingrained idea of the "seniority list". Unless you screw up badly or bust a couple of checkrides, your life is determined by your seniority number, not your ability as a pilot. As an airline pilot basically everything about your career is determined by when you joined the airline, not how good a pilot you are (as long as you meet the minimum requirements). Because Bob signed on 10 minutes before Joe, Bob will always get preference, promotion, etc. over Joe for everything job related unless Bob really f**ks up. It does not matter if Joe is a much better pilot than Bob, Bob always wins.

Thus a high seniority pilot good on the old stuff gets first dibs on flying the latest and greatest even though it may not be a good fit. Look at the senior captain who crashed the 777 at SFO because he could not hand fly an approach in a perfectly operating aircraft on a perfect flying day.

Yea, the slow spool up on the 727 did cause a few really bad landings. I wasn't a huge fan of that plane, ya never knew if it would give you a good or bad landing. But, it was versatile. One could be 5000 ft over the marker (3500 feet to high), and be stabilized at 500 feet for landing (which was the parameter for most airline in visual conditions.)

And a 2000 feet per minute is more than acceptable, if needed, as long as the plane is stabilized at 1000 or 500 feet. Heck that's done all the time today. Heck, I can do that easily in my Beechcraft, but rarely do because it's very inefficient.

 

[Seevee]

As for the seniority system, it works, but can be horribly unfair, especially if one was just born at the wrong time.

It's suppose to work the best for safety ..... all pilots are trained to one level of safety, if you're better, there's no reward. If you're worse, you get more training or out you gol The theory behind it is first come, first served as long as you don't crash or show up drunk.

 

[psneeld]

All complete horsecrap.


Back in the day, many pilots didn't have manuals, checklists, even had to have the ground crew start the aircraft.


Sure, back in the days of many accidents....but the reality was the good pilots survived longer.


Many pilots should never be pilots.


Heck, any pilots here ever tow a boat with a helicopter?


Probably few, but a pilot can figure out how to make an aircraft perform when it is not supposed to. Even if it means shutting off every dang system. And some have proved the impossible even in modern aircraft.


Like driving boats, some shouldn't, some can no matter what.

 

[AlaskaProf]

Based on what I've read, here's my understanding, and I would appreciate comment and correction...




- If the MAX trim automation kicks in, whether correctly or erroneously due to a bad sensor, etc., it is immediately over-ridden by any pilot trim control on the thumb switches, and remains disabled for 10 seconds.

......

- Questions: This nudge-down trim automation is new, but is there other trim automation that has been in 737s previously? Or is trim all pilot controlled, either by the thumb switches or the wheel?


- Question: I also read somewhere about the stick providing a vibrating feedback to indicated something. What was that?

Your understanding is pretty good and nicely expressed in layman's terms.


Any pilot input, either yoke movement or trim input overrides the MCAS for 5 seconds. The autopilot has its own trim circuitry, and if the autopilot is on, MCAS is disabled.


The "nudge down" feature is new, but the idea of protecting the aircraft against stalling is as old as jets. In all jet aircraft there is a "stick-shaker" which behaves as the name suggests if the aircraft approaches an aerodynamic stall. In many, if the "shaker" is ignored, a "stick-pusher" takes over.

 

[AlaskaProf]

"

"superannuated flight engineer who had been coasting along for some decades"

Guess you were a fighter pilot , they have the same contempt for co pilots and engineers , unneeded , as they can do it all, all alone.

HAR!!


No, all my flying is GA, single pilot, but I acquired about 200 hours in air carrier cockpits over my 30 years with the FAA. I liked the "clubby" atmosphere in most 3-man cockpits.


Speaking of flight engineers, I once flew with "the most popular man at TransWorld Airways." TWA was one of the last companies which would allow a mechanic to qualify as an FE with no path to the front seats. This particular guy always carried a Jepp case filled with condiments; salad dressings, hot sauces, etc.

 

[AlaskaProf]

Bloomberg is reporting that at the Ethiopian site they have found the stabilator jackscrew trimmed full nose-down.

 

[Ski in NC]

Bloomberg is reporting that at the Ethiopian site they have found the stabilator jackscrew trimmed full nose-down.

Yea, I read that too.

Hopefully we will get some info off the recorders, they apparently made it to a lab in France on thursday. Puzzling it took that long.

 

[Boat]

Yea, the slow spool up on the 727 did cause a few really bad landings. I wasn't a huge fan of that plane, ya never knew if it would give you a good or bad landing.

Talking about this to an older fighter pilot who was there in the very early days. He said one plane, F-100?, I think, once you turned final it was just a question of how hard you going to hit the ground. Too late to go-around after you turn final. Probably flame-out if you tried. They crashed near a thousand or so.


Come a long way. Take off and land on autopilot and blame someone else if it doesn't work every time.

 

[twistedtree]

Your understanding is pretty good and nicely expressed in layman's terms.


Any pilot input, either yoke movement or trim input overrides the MCAS for 5 seconds. The autopilot has its own trim circuitry, and if the autopilot is on, MCAS is disabled.


The "nudge down" feature is new, but the idea of protecting the aircraft against stalling is as old as jets. In all jet aircraft there is a "stick-shaker" which behaves as the name suggests if the aircraft approaches an aerodynamic stall. In many, if the "shaker" is ignored, a "stick-pusher" takes over.

Thanks, and on the MAX, would the stick shake when the "nudge down" feature activates? Or does it nudge down silently? Sounds like it's silent from what I've read, or what's implied by what I've read.

 

[Delfin]

Bloomberg is reporting that at the Ethiopian site they have found the stabilator jackscrew trimmed full nose-down.

That would explain the porpoising described by land observers. High rate of speed as the pilots tried to correct nose down and loss of altitude with power, fighting mal adjusted nose down trim. The FDR will tell the tale.

 

[AlaskaProf]

That would explain the porpoising described by land observers. High rate of speed as the pilots tried to correct nose down and loss of altitude with power, fighting mal adjusted nose down trim. The FDR will tell the tale.

An adjustment to my post. I think it is a pitch trim jackscrew, and not the actual stabilator.


Makes it easier to understand the sudden change of heart on the part of FAA. May suspect an MCAS fault somehow differs from the customary pitch trim runaway.

 

[AlaskaProf]

Thanks, and on the MAX, would the stick shake when the "nudge down" feature activates? Or does it nudge down silently? Sounds like it's silent from what I've read, or what's implied by what I've read.

I don't know the airplane well enough to say, and the real question for me is: does it move the yokes when it intervenes. Boeing design philosophy generally requires controls which are being operated by automation move as though the invisible hand is flying the airplane.


BTW, I may not have been clear, there is nothing subtle about the "stick-shaker". It will not allow you to overlook it.

 

[Civilitas]

Talking about this to an older fighter pilot who was there in the very early days. He said one plane, F-100?, I think, once you turned final it was just a question of how hard you going to hit the ground.

There's an excellent read on the perils of flying the F-100 titled, very tellingly:

"Bury us Upside Down"

It is primarily about using the F-100 as a stop-gap fast FAC (forward air controller) in the early part of the Viet Nam war, since the slower observation planes normally used in the role could not survive in the battle space. It involves a lot of discussion about the perils of that plane, regardless of combat.

 

[twistedtree]

I don't know the airplane well enough to say, and the real question for me is: does it move the yokes when it intervenes. Boeing design philosophy generally requires controls which are being operated by automation move as though the invisible hand is flying the airplane.


BTW, I may not have been clear, there is nothing subtle about the "stick-shaker". It will not allow you to overlook it.

Got it. I like the approach of the stick reflecting any automated controls so you know exactly what it's doing, or trying to do.

 

[Seevee]

All complete horsecrap.


Back in the day, many pilots didn't have manuals, checklists, even had to have the ground crew start the aircraft.


Sure, back in the days of many accidents....but the reality was the good pilots survived longer.


Many pilots should never be pilots.


Heck, any pilots here ever tow a boat with a helicopter?


Probably few, but a pilot can figure out how to make an aircraft perform when it is not supposed to. Even if it means shutting off every dang system. And some have proved the impossible even in modern aircraft.


Like driving boats, some shouldn't, some can no matter what.

Paul,

Not sure what you're calling complete crap, and not sure how far you're going back when pilots didn't have manuals, checklists, etc.....

But I started flying in 1968 privately and commercially in 1981 and I always had the above in any plane or operation.

Towing a boat with a copter would be interesting.... never been in one, they scare the bejesus out of me.

True some pilots should never be pilots and some some folks should never be boat operators.

 

[ssobol]

On the 737 (or any plane with underslung engines) there is a tendency for the nose to pitch up when power is applied and drop when power is reduced. This is countered by elevator and/or stabilizer forces. The control authority is dependent on speed. Higher speeds allow the elevator/stabilizer to generate more force per unit of deflection. Slow speeds reduce authority. In cases where the airplane is going relatively slowly and a lot of power is applied the nose up pitching moment could be quite high. If the aircraft is already slow, a pitch up in this condition could lead to a stall. Because the Max has higher thrust engines than the previous model 737, the MCAS system is designed to help control the nose up pitching by applying nose down trim in order to make the Max handle more like the 737NG. This allowed Boeing to claim that the handling of the NG and Max are the same and thus either one can be flown under the same pilot type rating.

In the 737 the stabilizer trim can be operated by the either pilot via switches on the control wheel. The autoflight system can also operate the trim. Usually only one operator (pilots or autoflight) can operate the trim system at a time, although it seems that the MCAS will only operate the trim if the autoflight is off. In each case the trim has two speeds (fast and slow) and the speed is dependent whether the flaps are up or not. High speed is for when the flaps are not fully up. The trim can be operated manually by turning the hand wheel. The speed of the operation in that case is determined by how fast the wheel is turned.

Because of the way the system is set up, any movement of the stabilizer trim will cause the trim wheel to move. In normal flight operations this wheel is often moving. If the MCAS moves the trim, the wheel will turn.

As has been mentioned, if the plane is being operated normally and there are no MCAS system malfunctions, the pilots should never experience MCAS operation of the trim.

If the aircraft is trimmed, the control column will be in the neutral position. Only when the elevator is deflected will the column move. Changing the trim does not cause the column to move. Normally the trim is used to hold the pitch attitude with the elevator at neutral. The normal method of flying large aircraft is to change the pitch with the elevator and then use the trim to hold it in the desired attitude. As the trim is set the elevator will come back to neutral.

A couple of things that have not been mentioned in the reporting that may have something to due with this incident.

- If the autothrottles are on and the plane is experiencing large deviations in speed, the autothrottles will be applying and removing power trying to get the plane to the set speed. Because of the pitching moment due to thrust, this can exacerbate any pitch control issues. We don't know if the autothrottles were on during this event, but normal takeoff procedure would be to have them engaged.

- If the trim was not set properly before takeoff (it has happened) the aircraft could be difficult to lift off or lift prematurely. In either case the force on the control column would be something that the pilot does not expect and could lead to an upset because of the reasons mentioned above.

- One of the things mentioned is that the aircraft was traveling at high speed at the end. With the trim full nose down (according to the jackscrew) the crew may not have the physical strength to pull the nose up or to hold it up for any length of time (even with both pilots pulling with both feet on the panel).

- The emergency checklist has a drill for trim runway. However, the first thing on the page is that the drill applies if the trim is "Uncommanded stabilizer trim movement occurs continuously." The MCAS does not operate the trim continuously, it does it intermittently. This is a subtle difference, but might cause less experienced pilots to think that this drill is not applicable to operation of the trim due to a MCAS fault. The pilots should be trained to use the runway trim drill any time the trim is not working as they expect.

 

[FF]

"Yea, the slow spool up on the 727 did cause a few really bad landings. I wasn't a huge fan of that plane, ya never knew if it would give you a good or bad landing."

All the jet engines of that era had a slow spool up time from flight idle..

The 727 gear were behind the center of rotation , so is someone attempted to flair the plane, as they would for other aircraft to slow the rate of descent, it simply banged the gear harder on to the runway.

Smooth 727 landings were a learned skill, not a matter of luck.