Ex-Boeing Manager Issues a Dire Warning to Travelers Regarding the 737 Max 9

Townhall ^ | 01/31/2024 | Matt Vespa

[cymbeline]

“In a pinch, the 737-Max can be a tricky aircraft to fly due to nasty surprises in its flight control system”

Thanks to both of you who replied — informative posts.

What do the hundreds of pilots that fly the planes think? Can the plane be flown with the MCAS system disabled?

My impression was that Boeing’s error was saying that the pilots didn’t need [much] additional training if they had flown 737s before.

It’s surprising that test pilots didn’t flag a problem before the plane went into service. Also, don’t the flight simulators simulate the MCAS along with the other fly

[OA5599]

All modern commercial airliners have engines that are forward of their wings and below their center of gravity. This includes all Airbus aircraft, including the chief competing craft A320.

All these modern commercial airliners have stall recovery procedures which require the pilot to pitch down to at least wings level prior to increasing thrust. This is because on all modern airliners, increasing thrust will pitch the aircraft further up due to their engines being below the center of gravity and forward of the wing. This is not unique to the 737 in general or 737 MAX in particular.

Specs are nearly impossible to find, but best I can find is that the 737 MAX’s LEAP engines are mounted four inches further forward and an inch and a half higher than the 737 NG’s CFM56 engines. (On planes that are 129ft or 143ft long, MAX 8 and 9 respectively.)

I believe the fan diameter is 17” greater on the LEAP’s, the MAX main landing gear length is unchanged from the NG, and the nose gear is 8” longer.

Regardless, the 737 MAX is not unstable like a fly-by-wire F-16 where the center of gravity is behind the center of lift. No, the MAX still has its center of gravity ahead of its center of lift, just like the entirely fly-by-wire A320.

One interesting difference between the B737 and A320 is the autotrim for pitch in the A320. It constantly trims for the pilot whereas in the 737, the pilot manually trims for pitch. Interesting that Boeing went with the sneaky automatic trim adjusting MCAS to make the MAX feel more like the NG.

[ducttape45]

How old is that aircraft? Is it a brand new model or has it been out for a while now?

[Flaming Conservative]

My brother has been an airline captain flying 737s for decades. I have lived on an airport with our airplanes for 25 years with mostly airline pilots.

---

That was then; this is now.

[fireman15]

That was then; this is now.

Statistically speaking, airline travel has continued to get safer during recent years. You are working yourself up over idiotic click bait type articles.

[fireman15]

The better point is you are much more likely to survive a fender bender than a plane crash.

Let's examine that statement: “From 2002 to 2020, there were 755 deaths during air travel in the US on domestic carriers. Nearly 75% of these deaths occurred in accidents involving on-demand air taxis, smaller aircraft of 30 seats or fewer that operate on an on-demand basis. Passenger car and truck accidents logged 498,016 deaths on US highways over that same time frame, an average of 26,211 fatalities per year.”

https://usafacts.org/articles/is-flying-safer-than-driving/

So from 2002 to 2020 if you don't count the commuters and small charters, there were approximately 10 deaths per year on major airlines in the US. Compared to 26,211 deaths per year on US highways. As a further reference approximately 365 people per year die from injuries in their bathrooms in the United States.

Approcximately 3.46 million people die in the United States per year. From 2002 to 2020 approximately 10 of those deaths per year were from airline travel not counting the commuters. From those numbers it appears that you 346,000 times more likely to die from a cause other than airline travel in the United States. And yes, please check my math.

https://www.statista.com/topics/1294/death/#topicOverview

Of course, 37% of all deaths in the United States are typically caused by cancer and heart disease. Airline travel is by far the safest way to get around... why you and others obsess over something that is extremely safe has mostly to do with sensationalized news coverage and irrational fear. Fortunately, you and others can easily avoid traveling by airline and increase your chance of survival by an infinitesimal amount approximately 1/36th of your chance of dying from an injury while in your bathroom. Of course, if you are replacing airline travel with travel over the road you are increasing your chances of death by at least 50 times by your own calculations.

"you are 50x more likely to have an accident in a car." From your post 32 in this thread.

[fireman15]

The better point is you are much more likely to survive a fender bender than a plane crash

The statistic you were quoting was deaths per million miles traveled not “accidents”. Currently there are over 6 milllion car accidents a year in the United States. That is compared to approximately 1,200 airline accidents per year and once again 75% of those are in small aircraft. 6,000,000 / 1200 = 5000 times more accidents in cars.

[T.B. Yoits]

The 737 Max is unstable in certain profiles without the MCAS correcting for it. From the article at the link in my earlier post:

"Without corrective input, at a high angle of attack a 737 MAX will continue to pitch up further, leading to a stall. As a result, Boeing finds the 737 MAX design does not satisfy Federal Aviation Authority (FAA) airworthiness criteria for stability, particularly Federal Aviation Regulation (FAR) 25-173 [see appendix]. If the angle of attack of the aircraft exceeds 14 degrees, the nose will rise on its own until the aircraft stalls, unless a corrective action is taken."

Appendix: Federal Aviation Regulation Airworthiness Criteria Sec. 25.173 — Static longitudinal stability.

Under the conditions specified in §25.175, the characteristics of the elevator control forces (including friction) must be as follows:

(a) A pull must be required to obtain and maintain speeds below the specified trim speed, and a push must be required to obtain and maintain speeds above the specified trim speed. This must be shown at any speed that can be obtained except speeds higher than the landing gear or wing flap operating limit speeds or VFC/MFC, whichever is appropriate, or lower than the minimum speed for steady unstalled flight.

(b) The airspeed must return to within 10 percent of the original trim speed for the climb, approach, and landing conditions specified in §25.175 (a), (c), and (d), and must return to within 7.5 percent of the original trim speed for the cruising condition specified in §25.175(b), when the control force is slowly released from any speed within the range specified in paragraph (a) of this section.

(c) The average gradient of the stable slope of the stick force versus speed curve may not be less than 1 pound for each 6 knots.

(d) Within the free return speed range specified in paragraph (b) of this section, it is permissible for the airplane, without control forces, to stabilize on speeds above or below the desired trim speeds if exceptional attention on the part of the pilot is not required to return to and maintain the desired trim speed and altitude.

[Amendment 25–7, 30 FR 13117, Oct. 15, 1965]

[dinodino]

The Max is inherently unstable, and a flawed design; even if built correctly, it’s still a bad plane. I do not fly on them.

[38special]

I’ve flown on them several times now and lived to tell about it.

[DennisR]

Sorry! I will try to do better in the future! /s

[OA5599]

I went to your link and there are a number of incorrect statements. I have never heard of Dennis Holeman, but he is not a pilot (nor am I) and is not in the aviation industry (again, nor am I). But he is wrong in quite a few of his statements.

The MCAS is not an anti-stall system. (Or at least that’s what Boeing claims.) It was designed to make flying the MAX “feel” like the NG so that training could be kept to a minimum.

You seem to believe the 737 MAX is an inherently unstable design. (Comparing it to an F-16 and F-117, and adding an article about the 767 running out of fuel and gliding to a runway, as if a 737 MAX is incapable of similarly gliding.) The 737 MAX has the same fuselage and wings of the 737 NG. Both planes are stable. Slightly larger engines mounted four inches forward on a plane that is 129 ft (or 143 ft) did not make it into an unstable fighter jet like an F-16. (Note that unstable aircraft have their center of gravity behind the center of lift, so moving engines forward a few inches did not likely move the CoG rearward.)

The MCAS was implemented to prevent the need for extra training, not to make an unstable aircraft stable. Where Boeing really screwed up was the fact that it relied on a single AoA sensor (despite having two installed on all 737s) and not having a way to disable the MCAS flight rules without disabling the entire electric trim system, and not accounting for the fact that the plane would be at such high speeds in a dive caused by a faulty MCAS that a human would be unable to move the manual trim wheel from the immense forces on the horizontal stabilizer. Very poor engineering to put it mildly.

The MCAS programming has subsequently been changed so that the maximum angle it can change the horizontal stabilizer is reduced, it will only initiate once instead of continuously, and will not activate if the two AoA sensors are in disagreement. Note that there was no change in the engine nacelles which create more lift than the ones on the NG during high AoA.

[Ikeon]

What are you an airline shill? I don't fly because the class of people who fly these days are 1970's greyhound bus passenger material, the TSA protocol is B.S. and hasn't stopped a single incident in 20+years, And i don't want to smell a fat guy eating a tunafish and onion sandwich next to me.

I also am a large frame 6' and my legs and my ass dont fit well in a airline seat.

Yes, I could fly 1st class for 4x the price. thats a given, but I'd still have to fly with animals.

[T.B. Yoits]

Boeing did not spend millions on MCAS to "make it feel" like the 737 NG. They spent millions on the MCAS system to compensate for the engine redesign. Then engines weren't "just slightly larger" and just a few inches further forward. They're an entirely different design with different performance. Boeing was avoiding having to recertify the airframe and push the cost of training pilots onto all their customers. That desire to cut or avoid costs proved deadly - twice.

As for "MCAS was implemented to prevent the need for extra training, not to make an unstable aircraft"...???...No one said that. It's the opposite, the aircraft was unstable in certain flight configurations and the MCAS system was designed to mitigate that.

The newer engines are more powerful than their predecessors and since they have a larger diameter, not only did Boeing move them forward, they moved them higher. The new power and location created the potential for the nose to pitch up during flight. If the nose was already high, the plane risked stalling. When the sensor detected the nose being too high, it automatically pushed the nose down.

The fact MCAS would activate at all is a clear indicator that the plane is NOT stable in all flight profiles. The pilots didn't push the nose up into the stall, the out of tolerance center of lift vs the center of gravity did. That's the very definition of unstable, right there in the FAR.

[fireman15]

I don't fly because the class of people who fly these days are 1970’s greyhound bus passenger material.

Well, I rode my share of greyhounds in the 70s and I have never minded the people next to me on airlines. Truth be told I even hitchhiked on occasion. Obviously, you are from a much higher class of people than I am. I apologize profusely for upsetting your delicate sensibilities.

[MinorityRepublican]

It was pointed out with the MAX accident that higher quality of pilot training could likely have made those incidents survivable.

True. But still the MAX is a bad design.

So as long as the plane is on the market, they should demand stringent training for a pilot to fly the MAX plane. It should be much more thorough compared to previous 737 models.

It should be expensive to train a 737 MAX pilot. Maybe that'll force the airlines to push Boeing for a replacement of the 737 MAX plane.

[pfflier]

But still the MAX is a bad design.

The incident with the plug is not a design problem, it is a production/maintenance oversight problem. Other recent incidents with Boeing airplanes in general are hyper-sensationalized reporting by the media

It has always been up to the airlines to train and certify their flight crews. I can concede that the MAX has different flight characteristics compared to the legacy 737. That does not make it a bad design or bad plane. It creates a training learning curve for operators as I pointed out in my original post.

[OA5599]

If you read my previous posts to you, you’ll see I’m well aware of the differences between the NG and the MAX, including the measurements of the fan diameter and engine relocation from CFM 56’s to the CFM LEAPs.

Yes, the MCAS was installed to make the MAX plane behave, i.e. feel, like the NG.

All modern aircraft pitch up with increasing throttle. All of them. The 737 NG and A320 included. This is not unique to the 737 MAX.

Are you calling all modern airliners unstable, or just singling out the MAX?

I repeat, all modern airliners pitch up with increased throttle. Yet they all have their CoG ahead of their CoL, so they are considered stable, including the MAX.

And yes, the LEAP’s are more powerful than the CFM56’s, so yes the pitch up will be greater. But again, this doesn’t make the plane “unstable” like your F-16 comment.

The main problem with the MCAS was that for some insane reason, Boeing decided to allow a single sensor failure cause the plane to fly itself right into the ground. (This is no longer the case.) I have already written about the other issues with the MCAS, which have also been resolved.

[T.B. Yoits]

Are you calling all modern airliners unstable, or just singling out the MAX?

Any plane that has MCAS or a similar system is unstable. That's why it has the system installed.

[OA5599]

I see. You’re not using “unstable” in a technical sense. You’re using it as hyperbole. I thought you were saying the 737 MAX was designed with relaxed stability like the F-16 you brought up.