Boeing Systemic Problems Continue

[L39Guy]

[/quote]

All excellent examples of the same corporate mandate to push products to consumers without due diligence. Just because others are just as negligent does not justify the practice!
Last I checked rushing a phone to market only caused tech envy and not mass fatalities.

It's all fucking bullshirt if you ask me.
[/quote]

Boeing's big mistake was assuming that professional, B737 type rated pilots could handle an MCAS runaway, which is identical in characteristics to the stab trim runaway that has been part of the B737 for the past 50 years. Boeing, every other aircraft manufacturer, every airline, every CAA and every pilot association is going to have to have a rethink of the assumption that pilots can actually hand fly an aircraft without the automation saving their skins.

For those of us who earned our chops hand flying aircraft this might seem ridiculous however when one considers that in many parts of the world there is no bush operation or corporate operation or any other operation where hand flying is mandatory. Airline pilots get minimal training (the Ethiopian had 351 hours total time of which 207 was B737) then start flying an airliner and are taught from day one to engage the autopilot at 400 ft and keep it on autopilot until just prior to touchdown so they have no manual flying skills or, if they did, they quickly atrophy.

As we have tragically seen with the MCAS issue and other, avoidable accidents, the lack of basic flying skills is becoming a significant factor in accidents now.

[Eric Janson]

The Turkish accident at Schipol was the result of a single radar altimeter input into the autothrottle; when the single source thought it was at zero feet it retarded the thrust levers, the speed decayed and the aircraft stalled, despite three pilots being in the flight deck. Boeing then modified the system to take two inputs.

I used to instruct on the 737 - this failure case was not addressed in the manuals or in training. I didn't know about this.

Of course back then it was "Manual Flight - Manual Thrust" - this would never have happened in normal operations. The autothrottle was only used for Cat II/III approaches and you paid close attention to what was going on.

On the airbus we have a bulletin in the QRH about this (same system design).

[Rezy]

Boeing's big mistake was assuming that professional, B737 type rated pilots could handle an MCAS runaway, which is identical in characteristics to the stab trim runaway that has been part of the B737 for the past 50 years. Boeing, every other aircraft manufacturer, every airline, every CAA and every pilot association is going to have to have a rethink of the assumption that pilots can actually hand fly an aircraft without the automation saving their skins.

For those of us who earned our chops hand flying aircraft this might seem ridiculous however when one considers that in many parts of the world there is no bush operation or corporate operation or any other operation where hand flying is mandatory. Airline pilots get minimal training (the Ethiopian had 351 hours total time of which 207 was B737) then start flying an airliner and are taught from day one to engage the autopilot at 400 ft and keep it on autopilot until just prior to touchdown so they have no manual flying skills or, if they did, they quickly atrophy.

As we have tragically seen with the MCAS issue and other, avoidable accidents, the lack of basic flying skills is becoming a significant factor in accidents now.

That’s really understating the problem I think. The MCAS problem is a combination of unreliable airspeed, a false stall warning, and a stab trim runaway all at the same time. It takes time to diagnose a problem, US Airways 1549 proved that, and unfortunately it doesn’t look like the Ethiopian crew was able to do that soon enough.
What basic flying skill would have helped them?
-Turn off the Autopilot? They did that.
-Turn off the Electric Trim? They did that.

[L39Guy]

That’s really understating the problem I think. The MCAS problem is a combination of unreliable airspeed, a false stall warning, and a stab trim runaway all at the same time. It takes time to diagnose a problem, US Airways 1549 proved that, and unfortunately it doesn’t look like the Ethiopian crew was able to do that soon enough.
What basic flying skill would have helped them?
-Turn off the Autopilot? They did that.
-Turn off the Electric Trim? They did that.
[/quote]

It all started with an Unreliable Airspeed (which includes the false warning) then, once the flaps were up and in manual flight, the Stab Trim Runaway. Two emergencies, both with recognized procedures.

The additional flying skills that would have helped would have been:

• autothrottle - off
  set 10 degrees pitch
  set 80% power
  (these are part of the NNC
  with or without doing the NNC, someone should have been flying the airplane, and this includes
  manage the speed, instead the speed got up to max velocity of 340 Kts, which made manual trimming nearly impossible
  trim the aircraft, to maintain an in trim condition, with large bursts of trim, not timid, little tickles of the trim switch

There are other airmanship issues that I think we can all learn lessons about too:

• with either problem, you are not going anywhere. Land the aircraft immediately
  if the problem stops, stay in that configuration and don't change configuration back to one that causes the issue to reappear
  know your emergencies

[Rezy]

I’m agree there are many things they could have done. I just disagree with the assessment that those responses are ‘basic flying skills’. And even your treating it like 2 simple emergencies, well that’s a total understatement because the preliminary report shows there was a lot more going on in the flight deck. Master Caution, stick shaker (that lasted the entire flight), “Don’t Sink” calls because of the descent after takeoff, and ATC interruptions. All while flying on faulty instruments with a runway trim. It’s not a simple emergency, which is why 2 crews failed to solve the problem.
Reduce thrust with a stick shaker going off? That’s not basic flying skills. that’s the only point I’m trying to make here.

[L39Guy]

I agree that there were lots of bells and whistles as there often are when something malfunctions...engine fire with lights flashing, horns blaring, confusion, startle factor, etc. But one has to fight through all of that and focus on the problem. That's why simulators are so good at practising that.

As far as the first emergency is concerned (unreliable airspeed), the Boeing drill is simple - autopilot off, autothrust off, 10 degrees pitch/80% power (it is a similar drill in all Boeing airplanes). That simple drill, even with all of the noise and confusion, was not done and it was clear that something was wrong with the airspeed system.

If it was a stall, then the nose should be lowered and power carefully added; it was not. Autopilot on at 400 ft. is a no-no in either case of a stall or an unreliable airspeed. There are three independent airspeed indicators in the B737 so the erroneous one can be easily identified and control passed to the pilot with the good airspeed indicator.

None of these basis things were not done in the ET case (and Lion Air too). Identifying the erroneous airspeed indicator, following the drill and maintain the proper speed is all basic stuff expected of a professional pilot. And this was long before the flaps were raised and the MCAS pitched the nose down.

[Rezy]

I agree that there were lots of bells and whistles as there often are when something malfunctions...engine fire with lights flashing, horns blaring, confusion, startle factor, etc. But one has to fight through all of that and focus on the problem. That's why simulators are so good at practising that.

As far as the first emergency is concerned (unreliable airspeed), the Boeing drill is simple - autopilot off, autothrust off, 10 degrees pitch/80% power (it is a similar drill in all Boeing airplanes). That simple drill, even with all of the noise and confusion, was not done and it was clear that something was wrong with the airspeed system.

If it was a stall, then the nose should be lowered and power carefully added; it was not. Autopilot on at 400 ft. is a no-no in either case of a stall or an unreliable airspeed. There are three independent airspeed indicators in the B737 so the erroneous one can be easily identified and control passed to the pilot with the good airspeed indicator.

None of these basis things were not done in the ET case (and Lion Air too). Identifying the erroneous airspeed indicator, following the drill and maintain the proper speed is all basic stuff expected of a professional pilot. And this was long before the flaps were raised and the MCAS pitched the nose down.

What clue did both crews have to run the unreliable airspeed drill?

[L39Guy]

The main clue was an otherwise normal take-off followed by stick shaker, depute normal power on both engines. The other indications listed in the reports also adds to the UAS diagnosis.

It is important to note that the Lion Air incident flight diagnosed UAS immediately, controlled the aircraft (including speed) and managed to land the aircraft (after flying it an hour and a half to the original destination).

[ahramin]

In any jet I have flown including the B737 a stall warning at liftoff is not an indication of unreliable speed. Stall warning combined with overspeed warning is, but stall on its own is not. This was not an unreliable speed indication and the airspeed indications were normal and correct all the way to the ground on both accidents.

[L39Guy]

In any jet I have flown including the B737 a stall warning at liftoff is not an indication of unreliable speed. Stall warning combined with overspeed warning is, but stall on its own is not. This was not an unreliable speed indication and the airspeed indications were normal and correct all the way to the ground on both accidents.

All three events had stick shaker, the ET accident report PDF page 11 states that there was a 20-25 knot airspeed disagreement, the CVR from the Lion Air incident states that there was an IAS DISAGREE annunciation.

If you look at the computed speed traces for all three flights in the two reports they show the same split therefore one can assume that all three had a 20-25 knot airspeed disagreement. I think it is probably a good assumption that the other two flights had an IAS DISAGREE annunciation too. Finally, the captain of the incident flight called for the UAS checklist.

I would suggest that this all points to an unreliable airspeed event.

[ahramin]

Interesting. So it looks like the entire Air Data computer was messed up? Not just a bad AOA vane? Or does a bad AOA vane mess up the Air Data computer?

the stick shaker activated and remained active until near the end of the flight.
 After autopilot engagement, there were small amplitude roll oscillations accompanied by
lateral acceleration, rudder oscillations and slight heading changes; these oscillations also
continued after the autopilot disengaged.
 After the autopilot disengaged, the DFDR recorded an automatic aircraft nose down (AND)
trim command four times without pilot’s input.

That's a lot of stuff to go wrong all at once. I'd say if they noticed the airspeed deviations it warrants the Airspeed Disagree Checklist, but in hindsight we can see that it wouldn't have fixed the problem anyway. I'm not sure I would have noticed a 20 kt difference while trying to deal with an apparent flight control problem.

[Eric Janson]

I would also suggest the possibility that the sound of the continuously operating stick shaker may have masked the sound of the trim wheel moving.

[plhought]

On the Max the AOA information is used by the ADIRS as part of the 'position error' correction for calculating KCAS/IAS...

Hence once you have a bung AoA vanes you get the unreliable airspeed flag.

Don't ask me why Boeing decided that - just another head scratcher.

[Daniel Cooper]

Why would they design a manual trim wheel that doesn't have enough mechanical advantage to retrim the aircraft after a significant runaway?

[L39Guy]

Why would they design a manual trim wheel that doesn't have enough mechanical advantage to retrim the aircraft after a significant runaway?

You mean being able to manually trim while flying around at Vne (340 kits+)? I don’t think that any aircraft can be manually trimmed at those types of speeds.

[digits_]

Why would they design a manual trim wheel that doesn't have enough mechanical advantage to retrim the aircraft after a significant runaway?

You mean being able to manually trim while flying around at Vne (340 kits+)? I don’t think that any aircraft can be manually trimmed at those types of speeds.

Huh? Why not? Quite some airplanes fly around at Vne quite often, especially during a descend. Why would an airplane not be trimmable at such a speed? Seems to be a big design issue if you can't trim it. Flying at Vne should be a non-event.

[sportingrifle]

L39 guy...

Almost any airplane with powered stab tim...ie all Airbus and the B777, 787, can be trimmed "manually" at any airspeed from any trim position.

The problem with the 737 stab manual trim is that it is just the pilot winding on a wheel connected by hundreds of feet of cable to the stab jackscrew. (The stretch in the cable created a whole other issue as well, but that is irrelevant here.) So the force able to be applied is limited by the pilots strength. This is why it takes such a stupid number of turns on the wheel to achieve anything...it is done with mechanical advantage. Worse, on the NG (and I presume the Max) the trim wheels were reduced in size to make room for the big screen TV's in the panel. Just as they increased the span of the horizontal stab!

The trim system doesn't even come close to meeting modern JAR25 certification standards. It is there only because it got "grandfathered" in from an airplane that weighed half as much and had half the power. There is a pretty convincing case to require a powered, redundant re-design of the entire 737 stab trim system on not just the Max, but the NG as well.

Cheers Sportingrifle.

[Raymond Hall]

Boeing waited until after Indonesian plane crash to inform FAA of 737 Max safety review

In the months after Boeing started delivering its new 737 Max jets in 2017, the company’s engineers discovered a problem: One of Boeing’s suppliers delivered flight control software that did not meet its requirements, Boeing disclosed Sunday.

It wasn’t until after a deadly plane crash involving related flight control software that the company informed regulators about the issue, which safety review committees from Boeing and the FAA determined was a “low-risk” problem, according to a statement on Boeing’s website.
The admission comes at a time when Boeing and the FAA face tremendous scrutiny over whether design flaws could have contributed to the deaths of hundreds of people in Indonesia and Ethiopia, where two 737 Max jets crashed in recent months under similar circumstances.
The disclosure could also feed into a broader inquiry over whether the process for designing and certifying commercial jets in the United States is flawed. The 737 Max was grounded worldwide in mid-March after the second crash brought the death toll to 346.

The software, which connects the airplane’s external sensors to pilots’ cockpit displays, is designed to alert pilots when sensors on either side of the plane are reporting conflicting measurements for the plane’s “angle of attack," a measure of how the plane approaches oncoming wind. Boeing included the alert as an optional feature in the 737 Max to alert pilots to potential equipment failures.

In its statement, Boeing said the planes can be operated safely without the alert.
“Neither the angle of attack indicator nor the AOA Disagree alert are necessary for the safe operation of the airplane," the statement reads. "They provide supplemental information only, and have never been considered safety features on commercial jet transport airplanes.”
Boeing’s statement Sunday comes a week after the Wall Street Journal reported that the angle-of-attack disagree alert was inoperable when Southwest Airlines and other carriers started flying the planes.

“The disagree alert was not operable on all airplanes because the feature was not activated as intended,” Boeing said in a statement last Monday.
When it discovered the software problem in 2017, Boeing assigned a committee to review the issue, which ultimately determined that the planes were safe to fly. But it wasn’t until November, 2018, after the Indonesian plane crash, that the company informed regulators at the Federal Aviation Administration. It is unclear whether Boeing would have been required to do so under FAA regulations. The company said it followed its standard operating procedures.

Later that month an investigative report from Indonesian authorities found that those sensors had malfunctioned in the final moments of the flight, and that pilots had struggled to overcome an automatic anti-stalling feature that nudged the plane’s nose downward.
The FAA review board found the alert to be a “low-risk” safety issue which would not render the plane unsafe to fly. An FAA spokesman said Sunday, however, that "Boeing’s timely or earlier communication with the operators would have helped to reduce or eliminate possible confusion.”

https://www.washingtonpost.com/business ... cac69824cf

[L39Guy]

Why would they design a manual trim wheel that doesn't have enough mechanical advantage to retrim the aircraft after a significant runaway?

You mean being able to manually trim while flying around at Vne (340 kits+)? I don’t think that any aircraft can be manually trimmed at those types of speeds.

Huh? Why not? Quite some airplanes fly around at Vne quite often, especially during a descend. Why would an airplane not be trimmable at such a speed? Seems to be a big design issue if you can't trim it. Flying at Vne should be a non-event.

Manually trimming at Vne with the trim at near full nose down trim? Why would one ever get that far out of trim at that airspeed? Perhaps I should have clearer. Basically in trim at Vne with only small trim applications, perhaps.

[L39Guy]

L39 guy...

Almost any airplane with powered stab tim...ie all Airbus and the B777, 787, can be trimmed "manually" at any airspeed from any trim position.

The problem with the 737 stab manual trim is that it is just the pilot winding on a wheel connected by hundreds of feet of cable to the stab jackscrew. (The stretch in the cable created a whole other issue as well, but that is irrelevant here.) So the force able to be applied is limited by the pilots strength. This is why it takes such a stupid number of turns on the wheel to achieve anything...it is done with mechanical advantage. Worse, on the NG (and I presume the Max) the trim wheels were reduced in size to make room for the big screen TV's in the panel. Just as they increased the span of the horizontal stab!

The trim system doesn't even come close to meeting modern JAR25 certification standards. It is there only because it got "grandfathered" in from an airplane that weighed half as much and had half the power. There is a pretty convincing case to require a powered, redundant re-design of the entire 737 stab trim system on not just the Max, but the NG as well.

Cheers Sportingrifle.

You are quite correct. Please note my above comment about Vne+being grossly out of trim and note also that the B767/777/787 backup trim is with electric motors.

Apart from the MAX accidents where the pilots failed to use the manual, electric trim to keep the aircraft in trim (and override MCAS), the B737 trim system, ancient by modern standards, has served the industry well. I am aware of no accidents as a result of it.