Become a fan of Slashdot on Facebook

 



Forgot your password?
typodupeerror
×
Transportation News

Ethiopian Airlines Crew Followed Procedures Before Boeing Max Crash, Early Report Says (latimes.com) 193

The pilots of a doomed Ethiopian Airlines jet followed all of Boeing's recommended procedures when the plane started to nose dive but still couldn't save it, according to findings from a preliminary report released Thursday by the Ethiopian government. From a report: The plane crashed just six minutes after taking off from Addis Ababa, killing all 157 people on board. The report, based on flight data and cockpit voice recorders on the Boeing 737 Max 8, was not released in full. Boeing declined to comment pending its review of the report on the March 10 crash. The Max 8 has been under scrutiny since a Lion Air flight crashed off the coast of Indonesia under similar circumstances in October. Thursday's revelations raise questions about repeated assertions by Boeing and U.S. regulators that pilots could regain control in some emergencies by following steps that include turning off an anti-stall system designed specifically for the Max, known by its acronym, MCAS. Investigators are looking into the role of MCAS, whose functions include automatically lowering the plane's nose to prevent an aerodynamic stall. The Max has been grounded worldwide pending a software fix that Boeing is rolling out, which still needs to be approved by the Federal Aviation Administration and other regulators. Further reading: Flawed Analysis, Failed Oversight: How Boeing, FAA Certified the Suspect 737 MAX Flight Control System.
This discussion has been archived. No new comments can be posted.

Ethiopian Airlines Crew Followed Procedures Before Boeing Max Crash, Early Report Says

Comments Filter:
  • Next up: (Score:2, Interesting)

    by Narcocide ( 102829 )

    They find out that some completely different bug causes the MCAS override to stay on even if you shut it off.

    Either that or that it is susceptible to external control.

    • by lgw ( 121541 )

      They find out that some completely different bug causes the MCAS override to stay on even if you shut it off.

      Either that or that it is susceptible to external control.

      Possible, but also possible the procedures were bad. Given these planes weren't falling out of the sky left and right, I suspect switching off the MCAS works (assuming it's done while the plane is still recoverable).

  • by EndlessNameless ( 673105 ) on Thursday April 04, 2019 @11:53AM (#58384024)

    So, to summarize:

    1. Boeing self-certified that pilots certified in type did not require additional training. (Prior to the recent deregulation, they weren't allowed to self-certify.)

    2. Pilots had to break out the manual during an emergency to properly control a system they were not trained to use.

    3. The system either did not disengage properly, or else it reengaged automatically, contrary to well-established norms for this aircraft type.

    Boeing screwed up, but it also happened because of relaxed oversight. The previous level of oversight seems more appropriate.

    Perhaps the FAA Administrator who made these changes should be forced to resign. This administration has had enough turnover that the President should be capable of appointing new leadership quickly.

    • by Streetlight ( 1102081 ) on Thursday April 04, 2019 @12:19PM (#58384206) Journal

      Perhaps the FAA Administrator who made these changes should be forced to resign. This administration has had enough turnover that the President should be capable of appointing new leadership quickly.

      The replacement administrator would likely be the Boeing's chief lobbyist.

    • by Anonymous Coward

      Your number 3 does not apply. The system disengaged and the pilots later turned it back on, the why is unknown at this point. It is possible it was already unrecoverable when they turned it off.

      • by Anonymous Coward on Thursday April 04, 2019 @01:14PM (#58384506)

        There seems to be a lot of confusion around how the MCAS system is "disabled" in the case of problems. The MCAS system itself can't be disabled. The procedure for dealing with runaway trim adjustment, a larger umbrella under which problems with MCAS fall, is to turn off power to the electric motors that turn the trim adjustment wheels. These are physical switches that can't be turned on or off without physical contact by someone in the cockpit. The plane can't restore this power, only a person can flip the switches.

        Removal of power to the motors prevents MCAS from being able to continue to add more nose-down trim. Unfortunately, most 737 pilots do not turn the trim adjustment wheels by hand when flying, because it is slow and awkward process. They usually use a small thumb joystick on the control yoke to adjust trim, which is carried out by the same electric motors used by MCAS. My guess is that with a bunch of nose-down trim, the pilots turned the power back on so they could make a large trim adjustment with the thumb joystick. But as the pilots add nose-up trim with the electric system, MCAS was again able to counteract that with nose-down trim.

        Basically, MCAS can add so much nose-down trim, and do it so rapidly, that even disabling the system leaves the plane in such a nose-down trim that it is unrecoverable. The pilots can't crank the trim wheels fast enough by hand, and turning the electric motors back on gives MCAS the advantage again.

        • by Anonymous Coward on Thursday April 04, 2019 @03:13PM (#58385374)

          Here is an article that states that when the jackscrew that adjusts the horizontal stabilizer is under load from aerodynamic pressure, the manual trim requires too much force to adjust trim. https://leehamnews.com/2019/04/03/et302-used-the-cut-out-switches-to-stop-mcas/

          They turned the electric trim back on because the manual trim could not be used.

          • Thanks, this is the only truly insightful comment here. If aerodynamic loading really is that much of an issue for the 737 trim wheel, then that calls into question previous models of the aircraft also - not just the MAX. It may just be that Boeing has gotten lucky in the past due to runaway trim being a pretty uncommon occurrence.

          • by labnet ( 457441 )

            737 pilots are actually trained for this circumstance and even the flight simulators simulate the jackscrew load on the trim wheels. They are taught to duck dive to release pressure to adjust elevator trim. The problem with the Ethiopian flight, was not enough height.... but once they had re-enabled the electric trim system, had they kept manually trimming up (then cutout the trim system again), they likely would have saved themselves.

      • The pilots disengaged the electric trim which was causing the plane to pitch down. However, since it had already trimmed the nose down so much, they were unable to pull the nose back up using only the elevators (i.e. the stick). They could trim manually by turning the big trim wheels by hand, but that wasn't fast enough while they were continuing to dive towards the ground. So they decided to reengage the electric trim, hoping they could trim the nose back up. But instead, the MCAS immediately started to tr

        • There in lies the question. The decision to reengage electric control, thus mcas, was made. Calculations will be made that take all the factors into account as to whether this was something that doomed them or it wouldn't have mattered. Timing is everything in these investigations in determining blame. Did the pilots react quickly enough? Did they go down a wrong path in their decision making at some point? If you remember even Sully was raked over the coals after saving an entire airplane worth of people.

    • by Talderas ( 1212466 ) on Thursday April 04, 2019 @01:09PM (#58384482)

      Perhaps the FAA Administrator who made these changes should be forced to resign. This administration has had enough turnover that the President should be capable of appointing new leadership quickly.

      The administrator of the FAA at the time of the certification of the 737 Max was Michael Heurta, who was appointed by President Obama. He took the position in December of 2011 and held it until January 2018. The 737 Max was certified in March of 2017.

    • The change which greatly expanded delegated certification was mandated by Congress, not the FAA. It was a part of HR 2115 "Vision 100--Century of Aviation Reauthorization Act" in 2003. Refer to section 227 - DESIGN ORGANIZATION CERTIFICATES. https://www.congress.gov/bill/... [congress.gov]
      • by sjames ( 1099 )

        In other words, Congress decided that regulation was evil because no private corporation would put profit first and now hundreds are dead and the short term profits are being paid for in long term losses

    • 2. Pilots had to break out the manual during an emergency to properly control a system they were not trained to use.

      Bullshit. Dealing with a runaway stabilizer trim is a procedure that is trained into every pilot. It ought to be automatic. "If the trim is malfunctioning, TURN OFF THE TRIM." End of problem. It's SO COMMON that even I, as a pilot who has never flown a 737 of any variant, know what to do when the trim system runs away. It's so basic that anyone who has an ATP certificate will know it by heart. It is the same thing that the dead-heading pilot on the earlier flight that did NOT crash did -- turn off the elect

  • Where is the link (Score:4, Informative)

    by jeremyp ( 130771 ) on Thursday April 04, 2019 @11:54AM (#58384026) Homepage Journal

    I'd like to RTFA, but there's no link to it. There's no link to the source of the quotation.

    • Re:Where is the link (Score:5, Informative)

      by jeremyp ( 130771 ) on Thursday April 04, 2019 @11:56AM (#58384032) Homepage Journal

      Found it. It's from the LA Times.

      https://www.latimes.com/busine... [latimes.com]

    • Re:Where is the link (Score:5, Informative)

      by ilguido ( 1704434 ) on Thursday April 04, 2019 @11:56AM (#58384038)
    • Re:Where is the link (Score:5, Informative)

      by Xylantiel ( 177496 ) on Thursday April 04, 2019 @12:48PM (#58384374)

      Yeah, some the articles don't really give the necessary details. The one I found that really discussed it is this [geekwire.com].

      Basically it is possible for the MCAS, in combination with other things, to put the airplane in a situation that is not easily recoverable without turning the system that the MCAS is part of back on. This is because the system that bypasses the MCAS isn't strong enough to turn the tail back to the right position. But when the electrical stabilizer system is turned back on, the MCAS just kicks in again and puts it right back in nose-down. There are ways to work it out but they require "non-checklist actions" as the article says. There is no way pilots can figure this out in less than a minute while the MCAS is driving them into the ground. So basically the whole idea that "they could just switch it off" only works in some circumstances. So now we see that it appears even the instructions to pilots were not properly tested.

      • There is no way pilots can figure this out in less than a minute while the MCAS is driving them into the ground.

        The report tells us it was six minutes from takeoff to crash. The manual trim is certainly "strong enough" to deal with the trim system -- that's what it does.

        And having one person diagnose while the other flies is why there are two pilots to begin with.

        • The report tells us it was six minutes from takeoff to crash. The manual trim is certainly "strong enough" to deal with the trim system -- that's what it does.

          All they needed to do was make a left turn for Laguardia like they're going to pick up the milk.

    • All Slashdot articles place the link to the right of the headline, next to the little icons.
  • Authority (Score:2, Interesting)

    by Anonymous Coward

    The word "Report" has such an authoritative tone. According to the report...
    And then you read who wrote the report. Of course they would conclude that their country, their people, their pilots were not at fault.
    You see this legal positioning stuff play out over and over.

    And all you can do is try to backpedal and say, no, the Ethiopian government isn't a reliable authority on the correct operation of a Boeing airplane. Then the argument goes to, well then who is?

  • BAD AD (Score:5, Interesting)

    by ghoul ( 157158 ) on Thursday April 04, 2019 @11:59AM (#58384060)

    The AD which went out after the Lion Air Crash said disable the MCAS using cutoff switches. What it did not consider is that if the plane is already nose down then the aerodynamic forces are too strong to use the manual wheels to make it nose up. The AD should have specified use your electric trim yoke switches to make the trim up and then cut out the electric trim so MCAS cannot make it nose down again.
    Also why is the MCAS triggering 6 minutes into a flight. Takeoff by definition is close to stall. It should be off during takeoff. If this plane cannot takeoff without MCAS then this plane is not safe. This is not a fighter jet where the pilot can eject if the software screws up or the plane goes unstable.

    • Also why is the MCAS triggering 6 minutes into a flight. Takeoff by definition is close to stall.

      Isn't that exactly the situation MCAS is designed for (takeoff)? It's not supposed to over-correct. It's supposed to correct for user action because the pilot wasn't retrained on the characteristics of these larger engines being placed where they were. If it's unsafe, the plane should either be scrapped or pilots re-certified for this model specifically, without MCAS.

    • by Anonymous Coward

      Because the pitot tubes that make up the sensors can freeze over (or have other issues, the ones on Lion air were repaired prior to the fatal flight) as the plane ascends or descends in certain conditions.

    • by ceoyoyo ( 59147 )

      Both flights seem to have run into trouble when they put their flaps up, engaging the normal (non-takeoff) flight regime.

      • by ghoul ( 157158 )

        Could they have extended flaps to switch of MCAS without switching off electric trim or were they too fast for flaps.
        BTW on the NG you can switch off autopilot input to electric trim without switching off the electric trim. In the Max if you want to switch off MCAS you have to switch off electric trim
        This malfunction would have been much easier to handle if there had been a dedicated MCAS switch off button. Hit the MCAS switch off and then use the manual electric trim switches to trim back to normal.
        How did

        • by ceoyoyo ( 59147 )

          IIRC, the Lion Air flight did put the flaps back down at one point, and everything settled down, until they put them back up again. The Ethiopian plane was apparently too fast, although presumably there was a window of opportunity earlier.

          • by ghoul ( 157158 )

            Couldnt they have reduced speed or does MCAS takeover the throttle as well to prevent stalls?

            • by ceoyoyo ( 59147 )

              I don't think MCAS interacts with the throttles. Possibly they could have reduced speed, again if they'd thought of it soon enough.

              One of the reasons for the MCAS system is that in any 737 (not just the MAX) you must not throttle up when in or approaching a stall because the under-wing engines contribute a pitch up moment. In the old 737s if you got into a stall and increased throttle you could get yourself into a situation where the plane would not pitch down. The engine placement on the MAX makes that no

              • by ghoul ( 157158 )

                Were they afraid if they reduced throttle they would lose the lift from the wings and the nose would drop even further?

                • by ceoyoyo ( 59147 )

                  Maybe. I think it's more likely that they just didn't think of extending the flaps, or didn't think of it until it was too late. They might well have reduced power since the pilots would have been trained to do that in response to overspeed.

    • Re:BAD AD (Score:5, Interesting)

      by wired_parrot ( 768394 ) on Thursday April 04, 2019 @12:24PM (#58384234)

      The AD which went out after the Lion Air Crash said disable the MCAS using cutoff switches. What it did not consider is that if the plane is already nose down then the aerodynamic forces are too strong to use the manual wheels to make it nose up. The AD should have specified use your electric trim yoke switches to make the trim up and then cut out the electric trim so MCAS cannot make it nose down again..

      This is a good explanation [satcom.guru] of the difficulty in trimming the aircraft in a mistrim condition by a former senior Boeing engineer. The short of it is that in the mistrim condition encountered by ET302, with stab nose down and the pilots pulling elevator nose up, the combined tail loads would've produced high jackscrew load opposing nose stab up trim that would be impossible to overcome with manual trim.

      Boeing did publish guidance for older 737 models on recovering on a severe nose out-of-trim condition, which would have required taking the aircraft into a roller-coaster maneuver to relieve the horizontal stabilizer loads. But given that they were already close to the ground, this was not an option. The other suggestion was to extend flaps, but given that the aircraft was above the minimum flap speeds, this was also not possible.

      In short, it looks like the fix to the problem was as much to blame as the problem itself

      • That section of the manual does mention reducing speed and extending flaps though. Either they weren't familar with it, or they weren't able to reduce speed for whatever reason. There still isn't enough data to draw a solid conclusion, but things are definitely looking worse for Boeing.

    • Takeoff by definition is close to stall.

      Isn't 6 minutes the time it needs to reach altitude? Because then multiple parameters change. Adjusting thrust? Flaps? MCAS could take in account multiple parameters/

    • And to further add to this, the relevant pilot procedure to recovering from severe mistrim condition, as provided by Centaurus on pprune.org [pprune.org]. Note that the procedure below is not included in the newer 737-MAX flight manuals.

      Extract from the Boeing 737-200 Pilot Training Manual February 1982 page 04.80.31. Edited for brevity

      Runaway and Manual Stabiliser - Recovery from Severe Out-of-Trim

      "In an extreme nose-up out-of-trim condition, requiring almost full forward control column, decelerate, extend the flaps

    • Why is the MCAS needed now? I understand it was there to avoid pilot training, but we are way passed that.
      If it can cause issues and you have to turn it off at times why not just remove it and let the pilots do what they are supposed to and push the nose down themselves of they have to.
      Of it can stall way too easily and pilots are not enough then still it would mean you have to discontinue the plane not enable MCAS.

      • That is a valid question, and one that the media frequently gets 100% wrong. Non-technical media frequently describes MCAS as an anti-stall feature. It is not. The intent of MCAS is to make the control column forces on the 737 MAX feel identical to a 737 NG during a stall, so that additional training is not required when a pilot is transitioning from an NG to a MAX.
    • Also why is the MCAS triggering 6 minutes into a flight.

      Where did you read it triggers 6 minutes into a flight? By all accounts all I could find is evidence that it caused problems 6 minutes into the flight.

      But in any case the MCAS system is designed to counter act the fact that the plane changes pitch with thrust due to the poorly placed centre of thrust thanks to engine placement. During takeoff thrust is constant so while you're closest to stall you're also least likely to need MCAS.

      • by ghoul ( 157158 )

        Let me restate what I meant. In my opinion MCAS should not engage below a certain altitude as a nose down attitude is dangerous if you dont have altitude to play with. The risk of stall (and there is a stick shaker to let pilots know) is less than of a nosedive into terrain.

  • by CaptainDork ( 3678879 ) on Thursday April 04, 2019 @12:15PM (#58384168)

    I was in the Navy aboard an aircraft carrier. I worked on the avionics but never serviced or knew about the anti-stall systems.

    That said, I do not recall two blades on either side of the nose cones.

    It sounds clunky to me. Shit that sticks out is subject to damage. Apparently, the two blades could be out of sync. There is a "double-vote yes," system that indicates when the blades are not reporting the same conditions, and a "disagree," warning light Boeing apparently provided as an "in-app," purchase.

    Small-revenue airlines did not opt for the expansion pack and didn't get the fucking memo as to how to deal with a cray cray "AI" system that can fly the goddam plane better than a human.

    "Stall," has a well-established definition and whatever method of detection works on other airlines is not the one Boeing uses.

    • by jabuzz ( 182671 )

      The problem is the two sensors. You need three is a safety critical system like this so one bad sensor can be out voted by the remaining two good sensors.

      Boeing have two options. Redesign the whole system to have three sensors which means retrofitting it on all delivered planes. That's going to be costly and time consuming.

      The second option is just to disable the MCAS and have all pilots flying the MAX variants of the 737 type certify. This will take time and makes the 737 MAX a much less attractive plane f

      • by ceoyoyo ( 59147 )

        Two sensors is fine, because it isn't really a safety critical system. All engine-under-wing airliners have the same instability problem in a stall, and the MAX isn't that much worse. If the system turned off on failure, it would be fine.

        Whoever approved using only one sensor was an idiot.

        • by Shotgun ( 30919 )

          Two sensors is not fine. Doubly so if the two are of the same type, because they are likely to fail in the same way.

          What is "fine" is doing the same thing EVERY single engine pilot does when flying in the clouds. At that point, the pilot is in the same condition as the computer: no outside reference and relying totally on what the instruments say. The pilot is trained to continuously crosscheck the instruments to verify that they all make sense and to cover up an instrument that is giving anomalous read

          • by ceoyoyo ( 59147 )

            Two sensors is fine.

            See what I did there? Same thing you did: assert an opinion with nothing to back it up. See the post you replied to for said backup. If you'd like to actually reply to that, instead of ranting, happy to discuss.

        • by jabuzz ( 182671 )

          Except when two sensors disagreeing can send your plane into an unrecoverable dive then that immediately makes it a safety critical feature.

      • Further the person or persons who signed off on using just two sensors

        One sensor.

        The plane has two, but MCAS only reacts to one.

    • by PPH ( 736903 )

      That said, I do not recall two blades on either side of the nose cones.

      Some fighters and other military aircraft don't use AoA vanes. Instead, they use a pitot tube [wikipedia.org] type sensor to sense the direction of the direction of the air flow. This type of sensor will just be a few more ports in the air data boom [wikipedia.org] and a few more pressure transducers.

    • Weren't paying attention, eh?
      https://upload.wikimedia.org/w... [wikimedia.org]

    • "Stall," has a well-established definition and whatever method of detection works on other airlines is not the one Boeing uses.

      There's three methods generally used. One is a small slit which activates a reed switch would be useful only for a warning light and not for any kind of control scheme, one is to use differential pitot tubes which since you have a problem with things sticking from planes I'm sorry to inform you also stick out from planes, and then there's the AoA vane sensor used by Boeing ... and ... Airbus, and because I was really bored I spent the last 10 minutes looking at aircraft pictures so you can also see them on

    • by mjwx ( 966435 )

      Small-revenue airlines did not opt for the expansion pack and didn't get the fucking memo as to how to deal with a cray cray "AI" system that can fly the goddam plane better than a human.

      "Stall," has a well-established definition and whatever method of detection works on other airlines is not the one Boeing uses.

      The MCAS does more than just stall prevention. It changes the input of the pilot to make the aircraft feel like how a 737 NG responds in order to prevent the new 737-MAX from having a separate type certification and having to retrain pilots on it. The problem is the 737-MAX has a radical change from the 737-NG, in order to fit the larger CFM LEAP engines they couldn't put them under the wing, instead they put them higher and mounted them forward of the wing. This has the side effect of putting the thrust di

  • They turned it off. Then they turned it on again. Did they get tech support on the line or what?

  • to optimize the system for maximum profit, compromising on safety. Maybe those procedures should be reviewed as well, not just the MCAS specific documentation.
  • - No one told them to firewall the throttles. Excessive speed made trimming more difficult.
    - No one told them to turn the malfunctioning MCAS back on, which put the aircraft into its final fatal dive.

You knew the job was dangerous when you took it, Fred. -- Superchicken

Working...