Boeing 737 MAX changes beyond MCAS

By Bjorn Fehrm

November 24, 2020, ©. Leeham News: Last week, we went through the core MCAS changes the FAA demanded from Boeing to lift the grounding of the 737 MAX 8 and 9. As the investigation into the MAX crashes deepened, changes were added beyond the core MCAS related changes.

A single sensor failure, like the Angle of Attack failures for Lion Air JT610 and Ethiopian Airlines ET302, triggered a multitude of failure warnings. These warnings absorbed the crew’s concentration, invalidating FAA certification assumptions on crew reaction times for critical trim failures. As a result, the FAA required additional crew alert and procedure changes for the MAX.

A multitude of warnings from a single failure

As FAA and Boeing played through what happened in the MAX crashes in Boeing’s engineering simulators, the cascading alerts triggered by a faulty single Angle of Attack (AoA) sensor stood out:

  • Stick shaker went on on the affected side from rotation and stayed on all the time, despite the aircraft flying with the correct speed and not being close to stall.
  • IAS (airspeed) UNRELIABLE alert triggered
  • ALT (altitude) UNRELIABLE alert triggered
  • AOA (Angle of Attack) UNRELIABLE should have shown but didn’t because of a bug in MAX’s software that tied it to the optional display of AoA on the Pilot’s Primary Flight Display (PFD, the Pilot’s electronic horizon display).
  • The speed tapes on the Pilot’s Primary Flight Display behaved strangely, showing too low speed and high speed concurrently in the ET302 case.

Several trim related failures in such an environment relied on the Pilots identifying the trim misbehavior within four seconds. When flight crews from different airlines were flying these scenarios, it became clear such assumptions were unrealistic.

Complete System Safety Assessment

The FAA went through Boeing’s System Safety Assessments (SSA) of the complete flight control system and its stabilizer control and demanded a complete SSA of MCAS, including upstream and downstream interfaces. A complete SSA includes Failure Mode Effects Analysis, Functional Hazard Assessment, and Fault Tree Analysis.

All possible failures were analyzed, and no scenarios were allowed that required immediate action of the flight crew. Boeing, therefore, introduced the Flight Control Computer (FCC) Trim Monitor to catch any faulty trim commands, be it for Speed Trim, MCAS, or Autopilot trim.

The Trim Monitor compares the trim commands from the two Flight Control Computers and checks if any difference exists between the computed commands.

If the monitor finds an anomaly, it stops the trim actions and displays SPEED TRIM FAIL. Speed Trim and MCAS stop working, the Autopilot disconnects, and the Flight Directors shut down. The change cleaned up alerts and stopped any dangerous trim actions.

The MCAS and Trim Monitor changes bring changes to the Pilots Flight Manuals, Checklists, Pilot training, and the content in Type Rating and Recurrent simulator training.

The changes affect procedures for Unreliable Airspeed, -Altitude and -Angle of Attack and then Runaway stabilizer, inoperative Stabilizer Trim, and failed Speed Trim.

Public review

All changes were reviewed by the four Certification Authorities (FAA, EASA, Transport Canada, Brazil’s ANAC) and checked by flight crews from the countries’ airlines. The crews had different backgrounds, experience levels, and proficiency.

The FAA then submitted all changes for public comment. FAA evaluated each comment to understand if it warranted any further changes to software, hardware, or training.

It’s the final result of all these steps that are the basis for the changes to MAX Software, Hardware (a wiring separation change to bring the MAX to current standards), Manuals, and Training. In total it forms the basis for the lifting of the 737 MAX grounding.

Changes to the 737 NG

The MAX findings were continuously checked against the 737 NG to see if it should trigger any NG safety changes. As the NG has the steering column trim cut-out switches active at all times, no safety-related changes were necessary (the Pilots stop any miss-trims by just holding against with the Yoke, an instinctive Pilot action).

But the failure behavior of the NG and MAX and the actions they shall trigger are no longer identical. It’s not optimal for airlines operating mixed fleets. Therefore, a change package for the NG is the next step for Boeing to bring the types in sync for Manuals, Checklists, Procedures, and Training. FAA and Boeing have not told us the time frame for this package and if there will be any software or hardware changes?

127 Comments on “Boeing 737 MAX changes beyond MCAS

  1. Thank you for the excellent article.

    What restrictions from the MMEL are expected in case of an AoA sensor failure?

    • I also understand there is a chip added? Can you clarify what role that plays.

    • The SPEED TRIM FAIL indicator remains lit at landing, and prohibits dispatch, if any event disables STS (including MCAS & AoA failures).

      Both FCC’s were already required for dispatch (indicator lit on ground for bootup FCC failure, Master Caution and on-side FLT CONT lit for in-flight failure).

      Here are the MEL changes from the FSB review:

      (1) Dispatch is not permitted with both autopilot systems inoperative.

      (2) The autopilot disengage aural warning system must be operative for dispatch.

      (3) The STAB OUT OF TRIM light must be operative for dispatch.

      (4) The speed trim function must be operative for dispatch.

      (5) The SPEED TRIM FAIL light must be operative for dispatch.

      (6) Dispatch is not permitted with both A/P ENGAGE Command (CMD) Switches (A and B) inoperative.

      (7) Dispatch is not permitted with both A/P ENGAGE Command (CMD) switch lights inoperative.

      (8) Dispatch is not permitted with both autopilot (A/P) disengage lights inoperative. Dispatch may be made with one A/P disengage light inoperative provided the autopilot disengage aural warning system operates normally.

      (9) Dispatch is not permitted with both Control Wheel Autopilot Disengage Switches inoperative. Dispatch may be made with one control wheel autopilot disengage switch inoperative provided the following conditions are met.
      a) Mode Control Panel autopilot DISENGAGE bar operates normally,
      b) Autopilot is not used below 1,500 feet AGL, and
      c) Approach minimums do not require use of autopilot.

      (10) Both control wheel trim switch systems must be operative for dispatch.

  2. I think the 737 NG + MAX crew alerting system should be replaced by a crew alerting system meeting the latest requirements. A system helping the crew in difficult circumstances instead of confusing it.

    Boeing was exempted from doing so by the FAA for the MAX. We now know the strength Boeing had on influencing FAA decisions.

    The issue with this systems has been inherited by the MAX from the NG & so far managed to sneak through. Why & how ?

    • This issue was raised by several of the proposed AD commenters and was addressed by the FAA in the final report. The alerting system with current changes was found to be compliant.

      “The 737 MAX complies with 14 CFR 25.1322, as specified in that airplane’s certification basis. The 737 MAX crew alerting system is not substantially changed from the 737 NG crew alerting system, which has been shown through service history to be reliable and safe.

      The FAA has determined the existing certification basis for the 737 MAX airplane is appropriate for the design changes necessary to correct the identified unsafe condition. The FAA lacks a factual basis to require any changes (simplifying the crew alerting system or converting to EICAS) other than those proposed in the NPRM and mandated by this AD.”

      • “Grandfathering” of old design & requirements is printed in fat letters across this. And it is very worrying to me.

        The troubled service history of this system has been cleaned up by excluding failures that have been corrected since. Then it suddenly looks ok again. And a streamlined FAA approved, because correction would be “impractical” (/costly). Next: everybody wants to forget, move on ASAP.

        Wait for the next NG/MAX crash where this system is involved. The process : smartly (let others) discredit the pilots / out-communicate the airline. Meanwhile point out to everyone they must wait for the official investigation report that will come out in 9-11 months, when everybody is payed off / moved on. Another one defused.

        Nearly worked on the Lionair MAX too. Maybe nothing has really changed & it’s indeed a cultural thing.

        • Keejse:

          The 737 is just the worst of the examples.

          As we saw in other modern jet crashes, the system also is no help.

          If memory is not shot, the Quanta A380 crew spend over 1.5 hours dealing with alarms when the engine blew up.

          As a nuts and bolts pilot, my take is the hell with the alarms, put this thing down and now.

          But they were trained to go through each alarms step and they had not a clue if the wing was going to fall off or if the engine they could not control was loosing oil and would rip off the wing.

          Programmers have been allowed to go wild and no one has reined them in on aircraft control system.

          There should be mandated standards but there are not.

          We would not want to stifle innovation would we?

          Oh yes we would, if its in the air, stifle away.

          • Yes, it seems to be the order of the day in product design. If you can’t dazzle them with brilliance, baffle them with computer overload of obvious or needless added systems.

          • Not sure if putting it down right away would not have been a disaster. The plane was heavy and a lot of systems were not operational. It may have gone off and ended in a fireball.

          • The Qantas A380 was 50 tonnes over maximum landing weight, the on board software couldnt give them a landing distance at this weight. However the crew were able to remove the wet runway feature as it was dry and the result was there was 100m to spare. So was marginal anyway and when they did land with one engine out another degraded and some flaps damaged , 4 tires burst.
            Being methodical worked in this case as many of the fault alarms were real and not ‘needless’

          • My kind of pilot. I’ve flown most Boeing’s except the 74 and Airbus. Give me a Boeing any day. Perhaps if the right seat guy had more than 300 hours, which is insane, that accident wouldn’t have happened.

        • “Early in the development of the 737 MAX, Boeing considered equipping the flight deck with its state-of-the-art flight-crew alerting system, called EICAS, the Engine-Indicating and Crew-Alerting System.” – Seattle Times

          Which was first introduced on the 757/767.

          So Boeing has bypassed such a system in all 3 of its 737 upgrades, the first for the 737 classic (84) , then for the NG (97) and finally for the Max.

        • As best you exaggerate.

          Major changes have been made to the systems.

          More are desired but are not important enough to delay RTS further, they are being studied which is essential for safety so new failure modes are not introduced (like MCAS).

          On the face of it, EASA has brought up a point, sounds like they judge ‘fail operational’ to be necessary to even discontinue a complex approach. I presume the question of whether or not ‘synthetic AOA’ is enough will be discussed.

          It is another example of a local difference, such as – many years ago – some countries in Europe having much more need for GPS LAAS for precision approaches because they had not been as rigorous on keeping other RF transmitters away from ILS locations. (IIRC the problem was that when two signals are of a certain frequency difference from each other they can create a third emission that could overlap a needed frequency (Localizer being somewhat close to consumer radio/TV stations.)

  3. What is the timimg on the 3:rd synthetic alfa probe EASA has been requesting and Boeing promised in addition to a stick shaker cut-out switch?

    • Timing is that the third sensor is required for MAX-10 certification, then to be rolled out to earlier models. Expected in 2022 under the current conditions. EASA has said this sensor is not required for safety, but is an enhancement.

      FAA has ruled out the interim use of the circuit breaker to disable stick shaker as non-compliant. So Boeing will need to develop a solution for that. I have not seen any estimate for when that will happen but likely the same relationship to MAX-10 certification.

      • From the EASA proposed AD today, EASA will allow stick shaker disable with the circuit breaker, until Boeing provides an alternative. TCCA may do likewise.

        • Any idea how sensible this is or not ?

          I.e. is it within reach of the pilots when seated ?

          Is it very clearly marked so that no mistakes can be made, and a circuit breaker for another system pulled instead causing additional problems ?

          Boeing weren’t keen on the circuit breaker being used, they may have had a valid reason.

          • The reason was the circuit breakers are behind the seats on either side, so someone has to get out of their seat in a potentially critical situation.

            “The FAA finds that an erroneous stick shaker, while it may pose a distraction to the
            flight crew, does not affect controllability of the airplane. The stick shaker circuit breaker
            locations also do not meet FAA requirements for convenient operation for emergency
            controls for the complete range of pilots from their normal seated position in the flight
            deck, leading to possible distraction from their primary duties to safely control and
            monitor the aircraft.

            Furthermore, inclusion of these additional steps would add cognitive and physical workload to an already substantial Airspeed Unreliable non-normal procedure, and errors in locating and pulling the correct circuit breaker may lead to other airplane hazards.

            Balancing the concerns associated with adding a procedure to pull circuit breakers against the distraction of an erroneous stick shaker, the FAA has concluded that the design is compliant and safe, and therefore no change to the proposed non-normal procedures related to silencing the 737 MAX stall warning is required for this AD.”

          • JakDak:

            A CB in the techy end of things is not intended as a control device.

            It can act that way, but CB mfg do not design them for that type of service.

            Its not that you will wear it out (caveat, not designed for constant use) and this would be rare enough not to be an issue.

            If you need to disable a circuit, you put a switch in an accessible location and let the CB do its job of current limiting.

        • Yes, the stick shaker circuit-brakers will have colored “stockins” helping pilots pull the right one, red and green to match starboard and port would be logical. RNP approaches will be banned by EASA until the 3:rd alfa probe comes on-line Still no metion of the 737-200 yo-yo manouver simulator training to offload aero loads on the horizontal stab at high speeds to be able to turn the Wheel.

          • The maneuver was brought up by commenters. The FAA responded that it wasn’t needed within the expected flight envelope. The training already covers moderation of aerodynamic loading by reducing speed and momentary easing of the control column. The goal of the training is to avoid highly loading the wheels.

          • The goal of an air bag is to reorganize you will need it and ensure it works.

  4. Is there any information available how the third sensor would work and be implemented?

    • The base concept is from the 787 where it uses GPS data (though in that case I believe its speed not AOA)

      • Some air speed input and comparison with GPS and ring laser gyro data it should be pretty straight forward programming to calculate an alfa with a only few degrees error margin to conclude witch probe is bad. Still it need to be verified in turbulence, wind shear and other weatcher conditions but that work seems to have been done already on the 787? Maybe the Chineese CAAC will speed up its incorporation and a stick shaker cut-out switch with a warning light when triggerd as a requirement to be incorporated before a certain Chinese New Year and if not the 737MAX will endure a new CAAC grounding.

    • It’s not mentioned as a requirement in either FAA or EASA AD’s. The FAA response to comments is that it’s not needed because safe flight is continued with an AoA failure. FAA also said they had evaluated all consumers of AoA data and concluded there was no flight safety issue caused by AoA failure.

      EASA has prohibited autopilot approaches to precision landings, based on the inability to resolve correct AoA after a failure of one sensor. They also said this was a temporary restriction. So from that, we might infer that they expect the third AoA sensor will be integrated in some manner with autopilot and landing systems. But pure speculation at this point.

      • The reality is AOA is not needed.

        Unfortunate (with all due apologies to Bjorn who was a fighter pilot) the airlines were taken over by fighter pilots during and post Vietnam War.

        It was part of their comfort zone (ore more acualy it serves a purpsoe when wild maneuvers are part of your existence )

        It does not serve any useful purpose for airline ops, just another item to go wrong and cause false alarms.

        Its not even on the PFD. You have your attitude indicator which tells you all you need to know about aircraft attitudes.

        I got to fly an MD11 Flight Simulator. All I needed was the PFD and the instructor call out for raising the nose.

        The PFD was perfect as were the auto throttles.

        I spent many happy an hour in a C150/152 in unusual attitudes (love em) with the simple version of a PFD and an audible for stall.

  5. That is quite a sad collection of down stream faults to be undiscovered until over 300 people are dead. I suppose that can be expected when you keep layering complexity and band aids on an aging design. And grand fathering the result.

    One hopes they have caught them all now….

    • Mark: That is a tough one as most of the findings had not caused any issue in the past.

      Much like house wring mandating certain size (12 gauge). You could use 14, its more than rated for the current. Its overkill to a degree but its a leel of safety as well.

      Ergo, the wiring separation is not done on the 737NG but is on the MAX (Boeing like so many things missed it, same issue on the KC46)

      So, the authorities cherry pick and say it has to be on the MAX per current regs (it was per reg on NG). But its the same issue.

      Its not ever known to fail and cross the two wires, but it is now a regualtion.

      So you have 5000 NGs that are identical to the MAX in that regard but will not be brought up to the same standard.

      The computer cross check and hot swap is the same. Its long been considered a prudent move, now for the MAX its mandatory and the NG sails on as is.

      Ironical at the rate of cancellations, the NG may have a longer produion run than the MAX.

      Again the possible faults in computers not doing sanity checks on each other has never occurred.

      Also to be kept in mind, you change one thing and you then have to change others.

      • TWA, I respectfully beg to differ, in reference to the 12 AWG vs 14 AWG.

        I am in the process of gutting and renovating my 3 unit building and have done most of the work myself, but have leaned on several certified tradesmen friends in certain areas – notably electrical & plumbing. (because burning the house down or flooding the basement is a bad thing, I am told…)

        Depending on where you live, the building code and how stringent the inspectors are, using 12 gauge on a 15 amp breaker will not pass.

        At the very least, you must run white tape around the red wire that goes into your panel, where it leads to the neutral bus bar. From what I understand, having run across this very situation, is that in the future your panel may be opened up by someone else – who has not done the work installing 12AWG & 15A setup and incorrect assumptions could be made.

        Inspectors don’t like to see this, I am told. You want 20A rated wire – use a 20A breaker and 20A receptacles – as I have in the kitchen for single circuit plugs. God knows the wife will try to run the toaster, coffee maker & microwave oven (and would plug in a hair dryer too, if she could, with a power bar)

        Don’t mix gauges and wires on the same circuit. Run individual circuits to high use areas (kitchen, bathroom) for receptacles where more things are likely to get used.


        Your analogy holds true. I am a big believer in over-engineering things. If I am told I can get away with using a 2×3’s in a wall I am framing, I use 2×4’s. Load bearing wall that I can use 2×4’s in? I use 2×6’s. Subfloor going down where I can use 5/8 OSB? I use plywood.

        Aeronautical engineering has huge weight considerations, but you can beef up in other ways, as you said…

        My $.02

        • Frank:

          Good reply.

          I lived and breathed controls, power distribution systems for 30 some years. Also wired half a dozen houses over the early year when I was a laborer (we could do it for the owner).

          In my industrial work, there were a few time we ran into the need for a 30 amp circuit breaker due to copier machines with 12 gauge wire. We put in 30 amp CB. Getting a wire from the panel to the end user was a nightmare.

          So while not casually we did it. Also keeping in mind, the Copier machine startup pulse was over 20 amps and sustained enough to trip the CB (15 amp will only take 12 amps continue so a 20 amp is only good for 18 continuous). Ergo, the sustained draw was under 20.

          12 gauge wire will carry 50 amps fine It gets into the code vs reality, and the code is extremely conservative (and that is a good thing). It not just the wire, its the connections and even the run (more than one staple has been put through a wire in a wood frame wall, ergo the pads on the stud if you drill the wall to run the wire.

          Our client manager was a former electrician, we had many a battle over code (his violations of mechanical code were far more egregious than my electrical accommodation (grin)

          If you get inside a motor (like a home shop air compressor) look at the wiring size! Yep, it goes down, 14 or 16. Same with 3 phase 480 motors, once you get into the cover, down goes the size.

          Controls panels are the same, big wire to it and 14 or 16 gauge control wire. hmmm. They have total control of the panel, control xformer and the fuses though.

          We had many a control fuse blow in fan panels, compressor panels etc. You would go in and nothing wrong.

          Ergo, I came up with a theory, I call it or Gregs LFF Theory – Greg’s Theory of Little Flipping Fuse theory is the polite version. .

          Why did the fuse blow? Circuit is fine, relays coils fine, xformers fine, replace, 3 – 6 month latter, blown fuse.

          A fuse is a thermal element. As you draw power through it, it heats up, power off of course it cools down.

          Issue is that transformers and relays coils are like motors, bigger draw on power up and then they settle down to much lower steady current.

          So, the fuse element work hardens and breaks. But only below 5 amps (I don’t think I had one under 5 + amps do that)

          Do you just keep replacing the fuse (we are talking 1/2 to 3 amp) or do go up the size?

          Ok, the circuit wire is more than capable of 10 amps, why 1/2. Yep, its above the steady draw of the control circuit but put a peak reading amp meter on it and you see a pulse to 5+ amps.

          So, my solution was to up the fuse size 1/2 or an amp and see if it held. The manager argues with me endlessly, but with hundreds of control panels and fuses blowing weekly in one of them????? Some of them in panic level equipment ?

          Aircraft design let alone safety is truly the poster child of tough.

          You can have both, but you can’t put MCAS 1.0 in as a cheap solution without people paying the cost.

          So, you think it all through, you look for failure possibles, you try to prove its not a good idea. Yes it takes work but that is what we are paid for. And I never got a bonus for it!

  6. Lots of work ahead to complete the hardware fixes in situ. Or will the planes be transferred to update centres? I suspect that work will be carried out by Boeing engineers?

    • Boeing is assisting airlines with traveling support teams, at the requested level, and of course doing their own stored aircraft. Some airlines had started as soon as the proposed AD was released. They requested credit for previous work in the comments.

      The mandatory training will be the main bottleneck, due to limited numbers of MAX full fidelity simulators.

      • Isnt the lack of simulators a bit of a red herring? Some mention Southwests 9000 pilots would need the simulator time ‘before’ putting the Max back into service.
        Surely a plane like the Max is based at a few airports and crew bases first. For the first 6 months maybe only 900 pilots need the sim time to fly say 50 plus planes. Theres a little loss in the flexibility of a single plane fleet but its not expected that would go on for years.
        I would start with say the Phoenix or Oakland crew bases only and expand from there

      • I posted an article on that down a bit in the blog entries.

        Right now Mosses Lake in central Washington is staring to process MAX.

        They did not say if they would fly them all there or get those sorted and then move onto the other sites.

        They are stored at Renton, Victorville (Everett as well)

        They want to do it in a hangar.

        They also have to check for FOD in the fuel tanks. If found it has to be cleaned out. Not sure if they are even allowed to fly it if FOD (I doubt it)

        • They are allowed to fly ferry without all the mods, but that entails the return from storage check.

          They cannot fly the required cert flight without the mods, or return passenger service without the cert flight. For new aircraft they also require an FAA cert inspection before flight & delivery.

          Some of the airlines have their own simulators, so their pilots will have quick access. More are on order. There’s a list of them (and locations) on the FAA web site. There were around 30 at the beginning of the year, probably 40 to 45 now.

  7. mark:

    Certainly a question, what to do.

    but they were not solving anything, they were just killing alarms one at a time. With that kind of damage there were hundreds if not thousands.

    But the situation itself was clear, an engine had blown up, they had no control of the outboard one (it ran out of fuel on the ramp after landing)

    As a pilot, I have always been interested in the response issues.

    In some cases its clear you work the problem, others, you get it on the ground.

    What they were into was analogues (my opinion) to a fire.

    All the facts on aircraft fires are, get it on the ground and get it on the ground now. If that means off runway, do it, its going to come down and you have some chance (and your passengers) if its controlled (Sioux City) otherwise none (Alaska Airlines Stab drive failure off SFO)

    Everything I read about the A380 was get it on the ground and do it now, its only going to get worse and you have not a clue how fast its going bad.

    In fact, the pilots tried to make the auto pilot do the landing.

    Computers are bad enough with known failures design

    There have been a number of times that an A3330 or 777 have done bizarre things that they do this day don’t know why. Fortunately at altitude and no crashes. Computers, weird stuff.

    So, with that many shorted and cut sensors going into he computers, you really do not know what might happen, they could simply flip the aircraft upside down and dive it in.

    This is not a dis on Airbus. The industry and all the research said that kind of a failure could not occur. At least 60% of the shrapnel by analysis and experience should have gone into the air not the wing. It did, massive damage not just to one engine, loss of conr0l of the outboard one and severing and shorting of sensors as well as massive structure. damage.

    You can only design to your assumption. This was way beyond that.

    The auto pilot kept disconnection and they kep0t putting it back in.

    There in lies my issues. The pilots have been trained to be system managers first and foremost and not pilots.

    They trusted an auto pilot system over themselves (which fortunately rather doing something it should not have it said, no thank you, this is what YOU get paid for)

    The pilots finally took manual control 1500 feet (if the automation system had done something there was no room for recovery)

    But when you really have an emergency, the system is screwed up (be it A380 or MAX) and then you need a pilot.

    Sullengerger is an example of a pilot first.

    First he had the co pilot fire up the APU. That gave him full aircar control and not just what is on the battery (degraded and seli controll, flyable but not as good).

    He also picked his best option and did not try to get back to the field.

    That is piloting 101 and many forget it, they try to get back to the field and crash.

    My take is they had a committed meeting with all the A380 pilots aboard and like any committee, you talk too long.

    They should have simply put it down ASAP. Incredibly fortunate to have not lost that bird.

    • Not mentioned in the article, is that delivery of remanufactured Apaches has increased this year, along with new Apaches. The percentages sound horrible, but:

      2017: 45 delivered, with 5 mishaps
      2018: 34 delivered, with 4 mishaps

      2020: 83 projected delivered with 11 mishaps
      (62 delivered through 3rd quarter)

      Also the complaint was registered in June, there was a spike in mishaps as production increased in early 2020, since has been resolved.

      Mishap is defined as unexpected damage or flaw in manufacturing and delivery. Many were contact damage while handling. Workers not being careful, same as FOD.

  8. This is from the EASA

    “We also pushed the aircraft to its limits during flight tests, assessed the behavior of the aircraft in failure scenarios, and could confirm that the aircraft is stable and has no tendency to pitch-up even without the MCAS.”

    So why do we need MCAS?

    • TW,
      Yeah, so EASA confirmed what some of us have been sure of since before the MAX saga started. The MAX is stable and has no pitch-up tendencies (stable aircraft do not have pitch-up tendencies). MCAS never had anything to do with changing the MAX from unstable to stable, or correcting any pitch-up tendencies.

      “So why do we need MCAS?”
      If you still don’t get it after over 2 years of discussions surrounding this topic, then you never will.

      • Mike, just let it go. I too wrote an explanatory response, but canceled it. Bjorn went over this again just 4 days ago, on Friday, so I realized it was pointless to explain further. This claim will always be with us.

        You should take comfort in that pretty much everything you’ve posted here about the MAX, has been validated and vindicated, based on all the investigations, reports, and rulings. That’s an achievement even if not understood or recognized. At this point, it no longer requires defense.

        With a different group, that would be welcomed. For some here, the animus against Boeing and the MAX are too strong for that to happen. But the truth of it is not lessened by that fact. I’m sure there are other readers here who understand and appreciate as well.

        • Rob,
          I didn’t let it go because it was TW. While there are regular commenters here that only want to take technical swipes at Boeing for whatever reason (I think lots of it is the ever present undertone of Airbus vs. Boeing in this forum) but they lack the technical knowledge or understanding to do so, I don’t think TW is one of those people. Yes, he takes regular swipes at Boeing management and culture, and the regulatory agencies, but those swipes are not really technical in nature. Most of his technical statements I see as reasonable and display a level of understanding, even if I don’t agree with them, or think they may contain errors (in my opinion).

          So, unlike some others here where I would not take the time to respond to their ridiculous technical statements, I chose to respond to TW because I was honestly surprised that his questioning of MCAS need seemed to imply a misunderstanding of its purpose.

          • Mike:

            Very fair statement.

            I am surprised in that supposedly, the FAA saw characteristic in the flight tests that said a fix was needed.

            There has been a great deal of discussion how MUCH pitch up that was and its alwyas been, it met the technical requirement for enough pitch up to have to do something about it.

            This is saying there was none. That is pretty amazing.

            as an aside. I have often run into that conflict of a tech spec causing more issues than it solves.

            Some (like small fuses blowing) I could deal with and some ran up to management level decisions as to, how much do you want to pay, because while I can make this work, it is a violation that has a possible consequences.

            I always felt there had to be some pitch up (it showed hints on the modeling) but to have none? That is a surprise.

            ps: I hope you see the issue with hits at Boeing Management and the FAA. If I had done my work like they did, I would have been in a soup line.
            Somewhere above the worker/foreman level it crosses a line that manages and their screw ups are excused and covered up.

            I do list reasons. The FAA hosed up the DC10 and it hosed up the 737 Rudder issue as well as Lata Air 767 crash (Boeing on the latter two as well).

            So its not new and you hope the layers of safety work though I am not surprised the FAA failed as well, they have been doing so for a long time. Ergo, FAA needs reform because Boeing never will.

          • TW,
            I think lots of confusion results from people being careless with the term, “pitch-up”. I think even Bjorn has done this. I know I have also, because it was easier to use the term others were using in my discussions than to go through the whole spiel of having to explain the terms every time I wanted to participate. If you will indulge me, I think now would be a good time to clarify what I think “pitch-up” means, especially in light of EASA’s statement about the MAX having no tendency to “pitch-up”.

            I would guess most of us here can agree that the larger LEAP nacelles on the MAX cause additional lift ahead of the CG at high AoA’s before stall. Since this lift is ahead of the CG, a positive (nose-up) pitching moment results. Another way to label this is “nose-up torque”. This nose-up torque is not noticeable by an outside observer, i.e. it does not produce an instant change in aircraft pitch attitude that anyone, even the pilot, can see. The pilot can, however, notice the immediate change in the control column force caused by this nose-up torque.

            On the other hand, an outside observer along with the pilot can easily notice aircraft pitch-up. I take this to be the rate of change of the aircraft pitch angle in the nose-up direction, or in other words, nose-up angular velocity. To be sure, the nose-up torque will ALWAYS eventually result in a nose-up angular velocity, or pitch-up. It won’t happen immediately, though, because the aircraft has considerable inertia (technically, moment of inertia) and it will take an amount of time before the pitch-up can build to a noticeable level.

            So, whether one considers the MAX to have a pitch-up tendency or not really comes down to the timescale over which the aircraft pitch changes. For a stable aircraft like the MAX, even if a nose-up torque appears quickly, the resulting pitch-up will only be tiny because it takes long enough to build that the pilot can easily provide corrective input well before the pitch-up becomes noticeable. I would say then that there is no pitch-up, even though technically a tiny amount builds up before the pilot corrects. This is not necessarily the case for an unstable aircraft. Here a nose-up torque can cause pitch-up to build so quickly that the pilot might have difficulty correcting quickly enough to prevent loss of control.

            I think that the nose-up torque produced by the MAX engines at high AoA has been mistakenly called pitch-up in many articles both within and outside of this forum. The confusion this causes would make the EASA statement seem surprising and out of place. I sincerely hope this helps and apologize in advance if this just adds to the confusion.

          • Good summary, Mike. I’ve mentioned the inertia in the rotation of the MAX around CoG before, but you did a better job of explaining it here.

            We also know the nacelle torque is proportionally small relative to the weight of the MAX, because the corrective MCAS torque is also small.

      • Of course the MAX is pitching up!!!
        Bjorn called it “nose happy”.
        If it were only about FEEL, Lufthansa wouldn’t have a need to block the last seat row on its 180 pax A320neo with Leap engines.
        Also, if it would be only about FEEL it’s not needed to put the nose down and kill lives.
        After 2 years Mike still didn’t get it LOL
        Mike, are you a Boeing employee?

        I still didn’t get an answer why Boeing invented “landing with spoilers” only for the MAX.
        Maybe Mike can give us some foolish Jedi mind tricking insight.

        • Leon, you were given an answer, you just didn’t accept it.

          The fly-by-wire spoiler system on the MAX created an opportunity for the special case of landing without elevator control. The spoilers can marginally emulate the elevator behavior in that case. The stabilizer can as well, but the spoilers are tied into the control column so more natural for the pilot on landing.

          Your attack on Mike is utterly unfounded, as all your attacks have been. Mike called it correctly from the beginning, but you can’t accept that either.

          Philip was one the commenters on the proposed AD. I read with interest the FAA refutation of his claims in the final AD. I’m sure you did as well.

          • Rob,
            I could always use a bit of amusement for my downtime over the Thanksgiving holiday. Do you have a link to Philip’s comment on the proposed AD?

          • It’s among the 238 comments for the NPRM and proposed AD. You’d have to search for it on the comment site. I don’t want to link directly to it, to maintain privacy.

            It was recognizable to me by the same arguments he made here. It’s possible there is another person with similar views, but I tend to doubt it. I’m sure you would recognize them on sight as well.

            Then in the final AD with the FAA response, only organizations were acknowledged by name, private individuals were not. So you have to read the comment first, then you can read through the responses in the final AD.

            It’s about 90 pages so takes awhile, but an instructive read to understand how the FAA reasons and makes rulings. Reading that gave me confidence that they tried to answer every question, and give a fulsome response to the comments.

          • Bjorn wrote in his article 5 days ago that the MAX has REDUCED STABILITY and Rob and Mike didn’t question it.

            If it were only about feel, Boeing would have thrown MCAS out in March 2019, calibrate the feel system new and do cert flights in April 2019 for RTS in May 2019. Just 2 months, but Boeing needed 20 months and lost billions on the way. Sure it’s about reduced stability.

            If it were only about feel there would be no reason to hide data, but Boeing is still hiding it.

            Even to mention the FAA, they are responsible for ET302.

          • Reduced stability in the sense that less force is required on the column for the same pitch. A slope change in the pitch moment curve, as Bjorn showed us (red vs green line). Due to changes in aerodynamics, thus a compensating correction in aerodynamics is required to address it (MCAS).

            In the absence of that correction, the pilot faces less force on the column at high pitch, but the MAX remains perfectly stable. Hence EASA reported this, as did the FAA, to help lay to rest the notion that the MAX is unstable and unsafe.

          • Leon:

            This is so convoluted its now impossible to sort out (maybe the grand jury wil.)

            But, there is a complete separate of flight characteristics (pitch up if it exists) vs stability.

            MCAS had nothing to do with stability (in fact a FBW commercial aircraft is unstable and barely flyable and almost imposisto to land without some computer ops)

            A 737 original to the MAX can be flown by hand with computers all dead. So, like a Cessna 150, its stable.

            The inanity is truly how MCAS morphed from soling a miner or non existent pitch up to killing people.

        • The term confuses people.

          See my attempt later to differentiate ‘pitch up’ from linearity of control force thus concern that a pilot might pull column back with a force he is accustomed to so over-control.

          • Isn’t there a use of spoilers during final approach, to keep nose wheels up?

            Touching nose wheels first is not a good idea, IIRC the airplane gets squirrely.

            I presume that use of spoilers is of flight ones, whereas ground ones are locked out until main gear compression. (They were on original 737s.)

          • And ‘Leon’ ignores that there is a regulation regarding linearity of feel approaching the stall.

            Integration is good.

        • I’d have to reread what Bjorn said, sounds like he was being colloquial – and I’d check context of that remark.

          (Do beware in general that Bjorn’s ESL status sneaks through sometimes, he still mixes should and shall. Here, should means recommended, shall means mandatory. (Which could mean required for function, required by contract, or required by regulation.)

    • TW,

      the MAX-7 was flight tested.
      Airbus did nothing for the A319neo too.
      Only A320neo and A321neo will get changes.
      It has to do with CG. Who knows how Boeing loaded the MAX for flight tests.

      • Leon:

        I do not claim to know how any given flight test was loaded.

        But, you have to load the plane at some point to its full aft and fore CG for the tests to be accepted.

        From what I have seen, initial flight tests are neutral CG and somewhat mid loaded.

        They then progress.

        You are aware that the A320 and the A321 have load placement that you have to adhere to to stay in CG?

        The MAX does not as best I am aware.

        Boeing management is guilty of some awful things, lethal even, but the MAX is not unstable. I am no Boeing apologist, but I won’t put out false information either.

        • TW,

          I didn’t say the MAX is unstable, it did many flights before, but it has reduced stability which isn’t allowed by regulations.
          Who knows how the MAX-7 was calibrated for flight testing, but one thing is proven, Boeing is in the cheating business.

          There were deals made in the past between FAA and EASA. EASA first agreed to no sim training in exchange for no Boeing self-certs. By time FAA knew that it can’t be certified without sim training. In the end EASA and TCCA had free choices of systems to be fixed. So there was still a deal in place between FAA and EASA/TCCA. A deal for what?

          The MAX is not FBW. This reduced stability can’t be compensated by software without FBW!!!

          If I were Norwegian I would do own MAX-8 flight tests and prove the reduced stabilty to show that FAA/EASA/TCCA made a deal because of reduced stability.
          It can’t be that the 180 seats A320neo needs to have the last seat row blocked and the longer MAX-8 needs nothing with even higher mounted engines.
          There is a reason for MCAS and it’s not feel.
          A319neo has no pitch up problems too.
          Boeing is still hiding when MCAS gets active. The 12-13% Bjorn mentioned are fake news. Why is there a need to hide this when it doesn’t pitch up.
          There was no need to ground the MAX for 20 months if it were only about feel LOL
          Long ago Boeing test pilots found the need for MCAS but EASA/TCCA can’t find the reason? hahaha
          Sure EASA/TCCA know the reason, they are not amateurs, they made a deal.

        • All aircraft require calculation of CofG before takeoff to ensure it is in approved range. (Also helps set optimum trim for takeoff, as on the 737.)

          With some systems of calculating CofG before takeoff F/As have to ensure distribution of pax weight in cabin is reasonable as the simplified calculation method has assumptions. And likely recognize high weight of a feetsball team (Canada and US definition).

          Some airplane configurations are awkward to load because empty CofG is not in the centre of the approved range – 737-200 for example. Lighter weight of wiring insulated with Kevlar helped a bit.

          Mixed cargo freight is a real challenge, Pacific Western used an alternative forward CofG limit on the 727-100C that required use of F30 instead of F40. Worked Ok into YRB which is 6000 feet of gravel, doubtful into YCN which IIRC was 500 feet of gravel. Both at sea level and not hot environment, both were key supply centres in the High Arctic.

          Gosh, I should go through my LeehamNews posts and write memoirs of airline and aviation design experience. 😉

    • Isn’t there a regulation, that Boeing first encountered with 767 design? (Boeing was able to meet the regulation with a few vortex generators on wings, instead of the triplex pushover computer they had prepared to use.)

      People get confused with terms like ‘no tendency to pitch up’ versus linearity of the pitch moment force with increasing AOA.
      I take ‘pitch up’ as meaning the airplane itself changes to a pitch up moment as AOA increases, as I understood T-tail airplanes were prone to (check what Bjorn said about the DC-9). I understood that the concern behind the linearity regulation was that pilots might overcontrol in quick response to something so pitch the airplane up too far and go into stall, with its loss of altitude which is not good near the ground. (As they would use the force they expected to need.)

      Note that, if I understand correctly, MCAS is disabled for the rest of the flight after some failure modes. (A TC engineer even wanted it removed from the airplane design as not needed – he had more confidence in pilots than whoever wrote the regulation that mandated a ‘fix’ to the nonlinearity concern, that MCAS is for on the 737MAX. Beware that people sometimes )

    • That is taken out of context.

      You only make it as complex as you need to.

      A commercial airline is a very very complex beast and its an incredibly difficult thing to design.

      That is why Boeing does not do it, the just reuse the old stuff!

      yes I could have helped myself but did not want to.

      • But some people tend to overdo.

        Circa 1968 a good engineering supervisor organized a multi-model meeting to get a standard Boeing approach to alerting if the crew went through an assigned altitude (a new regulation). TWA’s engineers wanted a flashing red light. A test pilot gave the meeting perspective on piloting priorities, so Boeing settled on an amber light and single chime. That pilot later was Chief Pilot of the 767 development, IIRC Tom Edmonds.

  9. [edited] Boeing Management. They should have spent the money to raise the height of the plane and avoided the suboptimal placement of the engine. Boeing needs to go bankrupt, get new management, and start over. [edited] just like their [edited] Starliner and everything they have done for a while now.

    • You are talking a new aircraft, and while I agree its two generation over due, to modify the 737 to that degree is to build a new one.

      Frankly I don’t know what would cause Boeing to truly reform.

      They blew 30 billion on the 787 due to sim-management and the mantra was to blame the workers somehow (and are still hosing up the 787).

      20 Billion and counting on the MAX so it never will return the ROI in any way shape or form and the bet goes on with miner shuffling.

      Unfortunate, they have too much defense business to go belly up.

      I see no hope to change it.

      Keep in mind though by moving 787 to Charleston, they are saving big big big bucks.

      Note To Boeing: I can save you multi tens of billions, its so easy I could do it.

      • Error, Boeing’s 787 management blamed outsourcing but the problem was failure to deal correctly with some contractors, perhaps exacerbated by what was in contracts and perhaps more cost-sharing than normal for Boeing. There were very good contractors and sleazeballs, some were divisions of the same empire like Smiths Aerospace.

        Unions rail against outsourcing, some claiming Boeing historically did not which is [bleep] ignorance of history such as Hal Korry resigning close to the beginning in order to make parts such as cockpit indictors for Boeing, and decades of integrating the best – such as using Collins Flight Director but Sperry gyros (not making either themselves, but evaluating and writing specs for contracts.)

        Hard to guess what the situation would be if the US gummint had not broken United Aircraft up. (Boeing, Pratt, and United Airlines were in the same corporate empire. That cost a leader -= The Mr. Boeing sold out in disgust. Fortunately Boeing found a new boss who was fairly good.)

  10. I am not going to go out of my way to avoid the MAX when I return to flying post-COVID-vaccine, but I’m continually gobsmacked by two things: first the MAX architects’ failure to consider that it might be time to add a modern airspeed and AOA system with a 3rd sensor of different technology (differential pitot tree), an integrating computer, and a synthetic airspeed/AOA computation as a sanity check just as a general part of preparing the design for the next 20-30 years of service. It could have all been done transparently to the flight deck controls and if borrowed from the 787 may not even have been all that expensive.

    And second the parties responsible for that risk analysis that apparently didn’t even consider what would happen if the AOA input started generating bad values, and therefore didn’t run it on the flight control hardware. Human beings all suffer from tunnel vision syndrome but that is an extreme breakdown of the design and safety system.

    • sPh, to clarify they did consider AoA failures, at the lower value of MCAS authority. They believed it did not pose a risk, as it would take several activations of MCAS for it to reach that level, and also believed that pilots would intervene well before then.

      “One of the noted hazards was an un-commanded or automatic MCAS activation that continued until the pilot took action. When developing this risk assessment, Boeing tested unintended MCAS activation in the simulator and assumed that commercial pilots would recognize the effect as a runaway stabilizer — a scenario which is covered in basic commercial pilot training — and react accordingly. ”

      Additionally they did not simulate multiple activations of MCAS, because again they believed pilots would intervene. The risk analysis was that it shouldn’t happen. That was the basis of the safety analysis that was approved by the FAA, and it was valid at that point, as far as anyone knew then.

      The problem came later, when there was no safety analysis of the modifications to MCAS, which increased authority and removed a safeguard. That is the process breakdown that occurred, as discussed here and elsewhere many times. And that was what opened up the vulnerability that manifested in the accidents.

      As far as the 3rd AoA, you can debate whether Boeing should have gone above and beyond, but the FAA said it’s not required under regulations and does not make the MAX unsafe. EASA concurred with that finding.

      Lastly it’s not clear that it would have made any difference in the accidents. The MAX did have a second AoA sensor, but it wasn’t deemed necessary for MCAS for the reasons given above. A 3rd AoA would have been similar, unless the causal breakdown as noted above was corrected.

      • >A 3rd AoA would have been similar, unless the causal breakdown as noted above was corrected.

        I think you are leaving out something taken as given, that if there had been 3 AOA sensors there would also have been a voting system to break ties.

        • Not left out, I said that the erroneous finding was that the additional sensor was not needed for MCAS. Unless that conclusion was changed, no difference n outcome.

          The MAX does not require a voting system, as it is not FBW. As the third AoA sensor is added, it will very likely not be in a voting capacity or algorithm. It’s more likely to be used as a reference, sanity check or fallback system.

      • All health and safety codes I have worked with state on the first page – often in bold type – “This code provides minimum standards. This code is not a design guide”.

        A good design accomplishes the purpose – or balances as many of the purposes as possible to maximum effect – while also meeting the minimum standards of the code. While I do not agree with many posters here that the entire concept of the 737MAX was wrong [1] there were clearly some bad architecture and engineering design decisions made in the execution of the project, and pointing lawyer-like to minimum code standards met by a hair doesn’t change that.

        [1] two things always glossed over in those posts (a) the customers still liked the 737 design tradeoffs over the A320 (b) many pilots who have flown both report that they find both aircraft acceptable but that each has its strong points and weak points depending on the mission, not that one is always and everywhere superior to the other

        • The purpose of the codes are to establish standards of safety. The purpose of the FAA is to evaluate and determine if the standards are met and safe operation is possible. There is nothing lawyer-like about that.

          Your contention is that Boeing should have gone above and beyond the established code. That same claim can be made for any aspect of design. But note that the FAA said that the addition of the third sensor would not contribute meaningfully or appreciably to safety. So that will be a factor in any design decision, and is also a factor in FAA rulings.

          The reason for the FAA conclusion is that the second sensor was already added, and the risks associated with MCAS were mitigated by other measures.

          EASA identified one scenario where the third sensor was necessary to enhance safety, that of AoA failure on precision autopilot approach to landing. The FAA viewed this as any other example of autopilot failure & disconnect, with the pilot stepping in. EASA viewed it as a case for which the autopilot need not disconnect, with a third sensor.

          The consensus was to follow the EASA view, with the feature being added as it becomes available. It is not retroactive to the NG because it is an enhancement. It’s absence does not imply a lack of safety.

  11. SPH:

    There was no risk analysis. I could have told you the single AOA was a lethal idea for that system.

    Its like a group thing where they all sit around and wind up nodding their head yes.

    No captain, running the Titanic at high speed in ice laden waters is only NOT a good idea and in fact is insane.

    They were not only not thinking, it was all based on cost cutting.

    The Titanic actually was a pretty safe ship, much like the 737. Operate it correctly and the bulkheads are not a problem.

    You can only conclude Boeing management is either insane or corrupt and maybe both. This is neither rocket science or the first rodeo, there is a 100+ years of experience behind aviation. It was deliberately ignore and continues to be.

    You can get off into the tech details but the reality is it was stupid to even propose an inanity like that and went downhill from there.

    A piss ant level controls tech like me could have and would have told them that.

    • FAA, JTAR, IG, Peter Lemme all disagree with you. All have reviewed the risk analysis in detail, that you claim doesn’t exist, and reported their findings. The quote I gave is from the IG report.

      These are just more false statements from you. That’s why I advised Mike to let it go. You can’t reason with non-facts.

  12. A lot of FAR’s are written after an airplane accident. You can piratically connect certain FAR’s to certain accidents. They are there to avoid making the same mistake twice. With the numerous design failures causing the 737-MAX accidents, where are the new FAR’s to make sure the same design failures etc. don’t occur tomorrow, in another aircraft design, or even the new 737-MAX? Especially in the computer control of major flight surfaces, and reliability risk analysis etc? Has even one FAR been proposed because of the 737-MAX crashes? Can similar design deficiencies, still be overlooked in future aircraft certification reviews? Has anything really changed in the design, acceptance and review process? It still mystifies me, how so many glaring errors, easily seen in retrospect, were able to be missed in the original review process. Of course, how many people even knew MCAS existed when the first 737-MAXes were being delivered? An entire software system, controlling a major control surface, and pilots didn’t even know it existed! Is it still possible to implement a secret computer control system without pilots knowing about it?

    • Another way to view the absence of CFR’s is that the MAX is basically a very safe aircraft, without critical design flaws, but rather had flaws in implementation of a new system. That’s why the system is allowed to continue after the flaws were addressed.

      The law is being changed regarding some aspects of FAA certification and ODA. Two bills before Congress at present.

    • Richard,

      Dickson is not a cert expert. Dickson is a Trump yes man.
      What do you expect? The US aviation system isn’t fixed.

  13. FAA chief giving briefing after piloting Boeing 737 MAX test flight in person is highly unusual. Why ? Doesn’t he trust his own people? does he want to promote the aircraft? Joining a test flight ok, but making a show of it doesn’t impress anyone in charge.

    • Having an FAA chief who is a certified pilot and able to check the MAX for himself is unusual. Having one who is willing to invest that degree of personal effort is unusual. Having one with the personal integrity to pledge his commitment, and back up his promise, is unusual.

      All characteristics that are lacking in the critics here. As is so often true, nobody here has the skills or capabilities to do what Dickson did, yet criticism flows like sewage, all downhill. Dickson doesn’t feel the need to throw shade at others out of petulance over a result which makes him unhappy. He doesn’t post the same complaints, over and over and over again, for months at a time, and even after those complaints are proven to be unfounded.

      The press conference was necessary after a high visibility event. There was extensive coverage of his statements that he would make the flight, as well as events leading up to it. Although you lack the courage to made a direct accusation here, your implication is that his purpose was to promote the MAX.

      In fact his purpose was to promote the thorough, open and transparent process he followed at FAA in the recertification process. To show that he was personally committed to that process, and put himself on the line. And that the conclusions reached by the FAA and other regulators, were not just words on paper, but a physical reality.

      As I mentioned before, among the tsunami of speculation and unfounded criticisms, was that the MAX was unsafe, this was being covered up, and nobody from Boeing or FAA management would actually fly on it. I read and heard that countless times, it was said many times to me as well. You go first. Let them be the first to step up. So he did, he stepped up. Dickson’s actions were a refutation of those claims, and many others that were similarly without basis.

      The irony here is that Dickson is criticized because he has personal integrity, not because he lacks it. The argument seeks to twist a good-faith selfless action to demonstrate truth, into a selfish act of deception and conspiracy. That’s more than a little bit sick. But representative of those who cannot accept the outcome, which is that the MAX is safe as it returns to service.

      • I agree Rob. His resume of being a pilot and flying the aircraft is a vote of confidence. More than anything, I saw it as a signal that he takes ultimate responsibility for signing off on safety

        • Thank you, Ted. It means a lot to me, for at least one other person here to recognize that, and state it openly.

        • Then as we are now categorizing the levels based on being a pilot, then my assessment takes a higher credibility over anyone that is not a pilot?

          While not a ATP, I was a commercial pilot, instrument rated (not required back then) SEL.

          I was top of the ratings by instructors in Unusual attitudes and instrument flying (not just one class, hundreds of students by several very good instructors).

          Based on that, my initial thoughts (and presented on Leeham) was that the pilots while not responsible, should have been able to pull it out.

          Another (how do you quantify Bjorn and his skill set) felt otherwise and has stated it explicitly that the pilot were overwhelmed.

          Clearly one of the people you need to use as a bench mark is Sullenberger – and he feels the same as Bjorn.

          That in turn means a couple of possible things.

          1. Most pilots would have been overwhelmed by the situation (and having tried to kill myself once I can concur with that)

          2. A few pilots might have pulled it out.

          Reality is we don’t know, but the reality is to that we have to design to the least capable pilots flying in any combo vs the best (in flight test or otherwise)

          Dickson has an axe to grind as the head of the FAA. I judge him on other aspects and his disagreement with the FAA and its need to be reformed is at the top.

          That does not mean he is wrong on the MAX being safe now. It does mean I question any decision he makes as an FAA administrator not a pilot. He will never be THAT pilot.

          I am finding disagreement withing pilots as to how hard it is to get to the stick shaker CB.

          As the 737 was designed as a two man cockpit, the CB should be accessible.

          The flip is, at some cost (too bad) you can add a couple of switches where they are easily accessible.

          As a pilot I did not have to deal with multitude of cockpit alarms.

          As a technician I did and I can testify the first thing you want to do is eliminate all the noise as it interfere with your thinking (I would put a stick shaker into that).

          One its is a distraction but two its sending continue different data to you, your training says you are stalled and you are trying to sort it out and shift to the data sets that say not but it keeps yelling at you.

          You don’t want something like that mental fight when you have problems enough.

          My flight instituctor asked me how I felt after the fist solo, was I nervous.

          No, I was just glad to get you out of the airplane. I knew I could fly it. No I know I am not pretty on nice landings, but I could fly it and it was really nice not having you there as a distraction.

          We went onto having gobs of fun with unusual attitudes and instruments .

          The icing on the cake was one horrible windy rainy day that no one was flying in and he asked if I want to do touch and gos. Sure.

          One of those days, my less than pretty landing skills came to the fore (some days are like that) and while not unsafe they were a bit on the ugly side.

          So I threw out the weather as an excuse (pilots do have ego). He asked me, you want me to do it!

          Yea, go right ahead.

          So he did, very nice landing. Held up has hands and said, Golden Hands! Yes, you are the man, I am parking it, I sure am not.

          • While a good flight deck, some things are a reach for panic situations – standby hydraulic pump on the original 737s for example (crew of PW314 needed to turn it on to power T/Rs when one came open during go-around in Cranbrook BC in February 1978).

            (That accident exposed a small window of time in which a T/R would not be latched yet throttle could be advanced – and T/R hydraulic power removed when going airborne in a go-around. The distance from latched was small but scrub of airflow at takeoff speeds was enough to pull it more open.)

            Fixes have to be completely thought out, somehow Boeing did not do that with the T/R restow feature on the 767, that was motivated by the PW314 tragedy in Cranbrook, so a Lauda Air 767 came out of the air. (Investigation of that exemplified that simulators are not always faithful, Boeing’s did not properly reflect actual performance with a T/R deployed.)

      • Rob,
        Well said! I couldn’t agree more! He said he would not sign off on the MAX until he had personally flown the aircraft and that was exactly the order of events. Talk is cheap, especially around here where some insist on living in the childish Airbus vs. Boeing, or Europe vs. USA mentality and because of this try, like you said, to twist an act of integrity into one of deception/conspiracy. It’s indeed sick.

        Dickson backed up his words with action. He should be praised for it, not jeered.

        • Thanks Mike. I agree that much of the foreign commentary here is driven by an inferiority complex with regard to Boeing and the US. Nothing else really explains the level of vitriol. That baffles me quite a bit, as I see no reason for it to exist, the playing field is actually pretty level. That’s why we don’t have a need to similarly criticize Airbus or the EU.

          If Patrick Ky similarly decided to pilot an Airbus, for whatever reason, I would commend him. There’d be no rational reason to do otherwise. But rationality is not the order of the day in much of the criticism that is posted here.

          • Another Rob-ism:

            As to who has the most sales? Aircraft being made? Modern?

            Airbus has it hands down.

            All Boeing has is US Corporate Law or lack there of that allows (acualy encourages) stupidly and incompetence in Management and lets any brain dead ding dong run a huge company into the ground.

            I never thought I would say it, but I am jealous of what Europe has in Airbus. Perfect no. But very good yes.

            Boeing is a poster child of how not to do things.

      • Rob,

        I agree. It’s a good thing having a pilot in charge of the FAA. I think it should actually be a requirement.

        Charles Bolden was an astronaut, Jim Bridenstine was a Navy pilot, I do wonder who Biden will pick to lead NASA ?

        The best way to lead, is by example. Don’t expect others to do what you won’t do yourself.

        As you know in the software world, we have the “eating your own dog food” concept.

        Perhaps Boeing should only use BBJ aircraft, and all company officials should only travel (as far as practicable) on Boeing aircraft ?

        • Nothing wrong with those ‘data driven’ types leading FAA, as a Boeing VP Flight Ops referred to engineers like me. 😉

          Perhaps having the opposite as second in command.

          As for using your own product, Microsoft had a practice of releasing early Beta or such versions of Office to its own administrative staff to get feedback. But I understand they stopped doing that, perhaps thus not surprising that Windows 10 and Office 2019 have differences from Windows 7 and Office 2010 that make no sense, and cutesy clutter.

  14. Covd: This is where you have to carefully watch what is going on.

    There are some sub plots to this. On the surface it looks like a mistake of half a dose may work better once the second dose is done.

    But its also sloppy testing and jumping the gun.

    So you watch carefully to see what the analysis is (and I will be the first to say I am no where close to having the background for that analysis, I rely on synopsis from a good communicator (Dr Fauchi would be one but not the only one.

    And one group doing it less than gold standard does not negate others who do.

    • More research is needed and will be conducted, but it may be a fortuitous error, as occurs fairly often in science. This was only the first interim result. The accidental half-dose arm will now be expanded in the trials.

      The initial half dose may reduce the natural immunity to the vaccine that builds up before the second dose, making it more efficacious. This is a difference from the mRNA vaccines where there is no risk of immunity to the vaccine.

      The earlier-stage trials do have variations in dosages built-in, to ascertain the most efficacious dose. This particular combination was not included in those trials.

      Key aspect is that AstraZeneca admitted all of this openly and have published their complete results in the Lancet. So no subplot or conspiracy. Just science progressing as it should.

    • @TW

      You are right – looks like their mistakes were multiple and they tried a half hearted cover up until commentors picked their results apart

      News is they are now repeating trials

      They have lost a lot of credibility

      How about mandatory health passports – will this fly?

      Meanwhile China and Russia are looking to make many friends with their cheap and cheerful

      • If the data prove out in the expanded trial, the mistake will be a significant benefit. It’s too early to tell yet but it was a good and positive development. It very well could result in a better vaccine.

        Some observers have jumped all over them in the mistaken notion that the results they announced were intended to be final. But they were clear that this was first interim, also that the numbers in the half-dose arm were insufficient and not representative. That’s why they are expanding the trial.

        So no coverup at all, despite the multiple comments above. Others could not “pick the data apart” unless it was fully published, which it was, voluntarily. So that too is disinformation. The data are what they are, nothing hidden or concealed.

        Ironic that the same observers who claim the vaccine process is rushed, themselves rush to jump to conclusions, in order to to discredit. If you are looking for a conspiracy, I guess you find one.

        Fortunately calmer heads will prevail, they will get improved data and have a fair hearing before the FDA and MHRA. There is already a rolling review started, which will allow the MHRA full access to the trial data in real time, as soon as the results are unblinded.

        • @Rob

          The pitfalls of the PR are not conducive to efficacity nor effectiveness

          Here’s Moncef Slaoui on the need for more and better data from AstraZeneca before enough evidence is in, and on the vital problem of uptake he is hopeful only

          « Whether large portions of the population will accept COVID-19 vaccines is clearly a matter of concern, both for Azar and Operation Warp Speed co-leader Moncef Slaoui. “Hopefully the majority of the U.S. will stay with an open mind in terms of accepting” vaccination, Slaoui said during the press conference. “Listen to all the data that will be shared transparently through the FDA reviews,” he urged.
          Slaoui’s remarks came just days after trial data from a third vaccine candidate from AstraZeneca raised questions about efficacy. The company said that one of the dosing regimens was only 62% effective—a result that paled in comparison to the 95% efficacy bar set by Pfizer and Moderna.
          Slaoui said AstraZeneca’s U.S. trial could generate more in-depth data soon, given the fact that the pandemic is raging again and “progressing so fast that it is very likely that not long from now…we may have enough evidence to assess the efficacy of the vaccine,” he said. »

          Jumping the gun with over hasty, confused and confusing PR has done AZ no good

          All this bodes ill for IATA’s mandatory vaccine passport scheme – another over hasty proposal with no administrative bones; it looks like they wish for governments and international health orgs to leave operation of the scheme to the airlines, on the grounds that objections to mandatory will be lesser in the case of private companies

          This is to forget that so far gvmt control of covid measures has been universal, and that many airlines are under gvmt control, and or beholden to gvmts for bail outs with many strings and conditions attached which render them less than autonomous and less than likely to wish to take responsibility for an operation outside their mandate – that is apart from the antipodes (population equivalent of Mumbai)

          • Gerrard, the point I made was that AstraZeneca very pointedly did NOT jump the gun. They released the results at the time prescribed in their trial protocol, just like the others. You must know that, the trial protocols are published in advance of the trials.

            Jumping the gun is your phrase and your conclusion. And ironically, you are jumping the gun in making them.

            There is a lot more data and analysis coming yet, unless people try to condemn them in advance, in order to undermine public confidence. I don’t know if their vaccine will be considered successful, but I do know they deserve to be able to complete their trials, and have it evaluated fairly. Surely you agree?

          • @ Rob

            No one agrees with news via corporate Press Release – AZ jumped the gun PR ing very inconclusive confusing and seriously un definitive ‘results’ – they’d have been better advised to keep their mouth shut and wait until they had something better to offer

            In this case AZ were overhasty, tried to happy face their results, and have provoked a backlash : this is foolish and un necessary

            The half dose given by mistake in trial is a good example of less than exemplary efficiency

            Their case is similar to the IATA proposal for vaccine health passports

            It is a rushed attempt to divert attention with an app and the private initiative of a very few airlines from the lack of any worldwide gvmtal or Health Org proposal and from the exceptional difficulties of putting the plan into practice let alone operating it

            The airlines are not going to, and are not able to take responsibility for any vaccine related problems

            Various gvmts operate vaccine waivers for the Pharma, for airlines as well?

            It is remarkable that between them all, IATA ICAO WHO and every gvmt in the world, they can only come up with this

            Given how badly managed/well disliked many airlines are – the public is going to trust them with a vaccine? Most likely not

            Leeham has run a series of articles on the technical efficiency of ventilation systems in planes, Boeing’s blue light and so on

            Yet all this is as nothing if a solution/solutions are not found for administrative international collaboration on tests borders quarantines and vaccines

            So far nothing much : they’ve had 8 months to think about this, yet….. ?menos que nada ?

          • Gerrard, I’ll drop this as Scott has asked us repeatedly not to fight about it. I’ll just predict that AstraZeneca will continue their phase 3 trials, report their results, and be evaluated sanely, by people who are interested in the truth.

          • @Rob

            One must not lose sight of the more important point – I have often raised this :

            There will be, probably, many vaccines produced and used :

            But for safe & universal global airtravel there has to be put in place only one system of internationally agreed standards, procedures and administration for pax testing and perhaps vaccination

            Indeed this system must, so it appears, be put in place in order to allow the global distribution of vaccines, via the use of pax as well as cargo planes, and the overcoming of the current patchwork of differing national standards quarantines border control régimes

            This is a subject to which we may pay attention : else it appears that a vaccine cold war may impose blocs, Russia China, Asia Africa, Lat Am, then US/EU – a jigsaw puzzle which will stifle not encourage airtravel

          • Gerrard, Rob: COVID is not part of this post. Drop it, or I will close comments for everybody.


          • @Scott Hamilton

            I agree : vaccines will be common

            Essential is the ways and means to ‘re certify’ airtravel, especially international

            Here covid forms a hard background, but what is complex and worth discussion is the operational detail of administrative regulation, with airport and airline and oems

  15. The 737 was originally designed and built in the 1960’s. Over a half century ago. The engine thrust and takeoff weight is now twice that of the original 737.
    The current glass cockpit looks and operates much differently than the original steam gauge cockpit. There are now complex flight control computers
    in the new 737-MAX’s that weren’t even conceived of in 1967. The wing design has been modified to add winglets (shark fins) to the tips of the main wings.
    The 737 Amended type certificate now prints out at almost 100 pages in length.
    The Boeing 737 Type Certificate
    The Boeing 737-specs (Thrust / Weight through the years)
    When do you stop “grandfathering” the 737 design, and call for a completely new Type Certification? A completely new design review top to bottom?
    According to the FAA Section 21.19
    “Section 21.19 requires an applicant to apply for a new TC for a changed product if the FAA finds that the change in design, power, thrust, or weight is so extensive that a substantially complete investigation of compliance with the applicable regulations is required. ”
    I say that the 737 design amendments have been stretched past the point of requiring an entirely new Type Certificate.
    Over 50 years of grandfathering former rules, with the doubling of thrust and weight along with a new wing and tail design
    requires an entirely brand new type certification.
    Why has the FAA let these extensive changes to the original 737 design go on and on by just amendments to the original 1960’s Type Certificate, of 50 years ago?

    • “Grandfathering” has been beaten to dust here, but in fact was not a factor in the MAX certification.

      The 737 family has undergone 13 type amendments thus far. The A31x-A32x family has undergone 43 type amendments thus far, over several more models. Those models have undergone similar changes in thrust and weight, often using the same engines as the 737.

      For each type amendment category (CFR section), the aircraft must be shown to be compliant with the regulations in force at the time of the initial type certificate award. For the MAX, that was 2012. Exceptions can be requested but they must be approved individually by the regulator. All of this is listed in the type certification document.

      Further all this has been done according to the rules, which were reviewed and found to be a correct and appropriate application.

      • Rob-ism:

        No, this is not grandfathered, it is just in certification for the standards at the time.

        Bring on the Wright Brothers!

        Earth to Rob: You just listed the definition of grandfathered.

  16. The FAA killed it 20 years ago after the same trouble certifying the 737NG.

    But then, after the 787 certification / financial drama and NEO launch, Boeing had to be saved. Congress put Boeing at the helm of their aircraft certificatio (2012 FAA reform act, 2012 re-authorization, streamlining DOA).

    IMO the 737 MAX could be certified using product change rules. But they should e.g. have finally added EICAS, meeting post 2000 requirements.

    The 777x is more dramatic. New wings, engines, fuselage, tail, landing gear, cockpit, systems. A new aircraft certified as 77W variant.. Opposite of what JATR recommends. Now it’s delayed for years..

      • I think he is spot on if not eloquently put.

        Boeing management has used its power in congress to corrupt the FAA (which was not that good to start with)

        Remember the 787 battery Self Certify by Boeing?

        I don’t know how the 777X will play out. Clearly they had a major failure in the fuselage blow out.

        Like the 787, it can be all fixed. Its vastly better (and amazingly) lower cost to do it right in the first place.

        But as a famous former worker put it. We do it right because we do it twice!

        What I find amazing is that people say the FAA is now corrupted.

        They alwyas were corrupted , not sure why it took this long to see that.

        The current FAA is just more so.

        • “Boeing management has used its power in congress to corrupt the FAA”

          We will continue to disagree on that, the system is one of delegation of much work, with FAA writing advisories and regulations and overseeing the process.

          I gather that a substantial part of the 737MAX MCAS problem was FAA understaffed and with too many newbies. People do retire, many of them early when Congress bleeps around with funding. Some retirees become DERs, such as Mike deWalt who was an NRS for software, and Greg Dunn who was an AE in SACO – sharp, engaged in dialogue, evaluated people, and held the line when he judged necessary.

          FAA people sometimes go out of their way to advance aviation, one of the ATC datalink people Peter Lemme recently chronicled came up with the idea of repeating the altitude clearance in different terms, to catch errors. (Use both numbers and words, probablility of both being corrupted the same is very remote. Subject was called CPDLC, sometimes under the FANS catchall. Very useful to reduce spacing in oceanic/remote where there is not skin-paint radar.)

  17. Gerrard White:
    You go on about vaccines even when told not to.

    Certainly standard regulations are very important to international commerce in airplanes, that’s what the four competent experienced ones are trying to do mostly with modifications to the 737MAX. Following the lead of Craig [brain fade] of FAA and Gerry Marsters of TC circa 1980, which led to much better cooperation with European regulators as well. Instead of the fighting by TC with FAA that followed the loss of a DC-8 in central Canada.

    But standard airline operating procedures for health are off-topic thus wasting bandwidth on a subject many are having difficulty understanding. As are political debates, much as I am eager to educate TW and others on. :-o)

    • Craig Beard was an FAA executive, chief of Airworthiness at least, as was Gerry in TC. (Gerry came out of National Research Council and did well in leadership role.)

  18. TW,

    With reference to your comment some place above, “in fact a FBW commercial aircraft is unstable and barely flyable and almost impossible to land without some computer ops”.

    Could we once and for all make it clear: No, no and no. No commercial jet, whether it has fly by wire or old fashioned steel wires, are unstable!!! When an Airbus has lost a number of systems and are down to direct law, there is a direct relation between sidestick movements and the control surfaces (it switches to this mode in the flare also BTW). No stability or augmention, no protections, but the aircraft is perfectly flyable – as a 737 with sidestick instead of a yoke.

    I know, I just checked out on this thing, and half of the simulator training was flown in alternate or direct law…

    FBW fighters, like the F-16 (and some helicopters maybe), are unstable, yes, and require functional flight control computers to control, but no civilian airliner would ever be certificated if they were aerodynamically unstable.

    • Geir A:

      I was using unstable overly loosely.

      If you would look at the details, you will find that I said hard to control in level flight in direct and almost impossible to land.

      What you are missing is the difference in degraded control law and system vs all 3 computers going off line.

      Ref is SU1492 flight. After the lighting strike it was in Direct.

      Per Bjorn, that is extremely difficult to fly. Its almost impossible to land in it.

    • Helos are a very different beast, ‘nervous wings’ I call them from working with them.

      I never observed autopilot function during my test fight direction and observing of a few types, my focus was elsewhere.

      I did work with a pilot who had an AS332 Super Puma try to kill him. On liftoff the machine immediately banked to a new heading, rotor blades hit ground, didn’t penetrate cockpit much. (They tend to wrap around the nose.) Cause was some electrical-hydro-mechanical piece that failed so did not properly disengage an autopilot/stability system, helo had been turned around after shutdown.

      (Same pilot had the nasty experience of a different type catching fire after landing, I don’t know what cause was, ambulance configuration so had much oxygen on board.)

      • But some DS in Okanagan/Canadian Helicopters refused to accept that there were sensitivities of helicopters not in fixed-wing aircraft. (Like rotors, which are not fail-safe. And vice-versa, helos not being pressurized for example.)

        And they pulled the scam of under-estimating cost of modifications to increase chances of management approval, then pushed to rush and cheap. Result was modifications that were less saleable to others because they were clunky and more costly to implement than they could have been.

        Both categories of [fools] were often licensed AMEs who were supposed to know bleeping well that rotor systems were critical. As for sales people, I estimate that a large potential customer for air ambulances did not sign up despite half of the cost being paid by resource companies to extract injured workers. Decades later it did with a different operator, using essentially the same configuration as I led getting an STC for.

  19. Many people need to read Figure 4 of Bjorn’s

    Noting it shows what Bjorn calls ‘reduced stability’, but still a _down_ pitching moment approaching stall.

    And noting it shows what I called non linearity of force required to raise the nose, specifically less force nearing stall AOA, which is the target of the regulation that people are ignoring.

    And perhaps of some interest also note the detail, that change of force with increasing AOA force actually levels off in stall conditions, compared to the NG.

    Caveat: Bjorn’s figure may or may not be completely accurate but illustrates the concern.

    Comment: I question the need for MCAS or other protection given the small amount of change, as a TC engineer did, but it is a regulation and has been since before the 767 was developed circa 1980.

  20. Interesting comment about a small airplane:

    “With full flaps out, we had a considerable amount of power in to arrest the sink, and taking that out gave us an easy stall break, positive, but straight ahead. A lot of high-lift airplanes today sort of mush along in a semi-stalled condition, lulling the pilot into thinking all is fine, while in fact they are sinking toward the ground at an alarming rate. The break in the Bearhawk 5 gives you a good warning that yes indeed, it is time to relax the back pressure. Add a little power, relax the pull and fly right out of it.”


    The Bearhawk is a high wing configuration like C172/180 and Murphy Moose. Has high lift wing to go into short air strips.

    Airplanes are like restaurants I say, everyone wants to have their own design. Many good chefs perhaps but not many good business people (visit Arlington WA airport for remnants of companies).

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