Ethiopian airliner down in Africa

[Jo90]

Having read (well skimmed) the interim report of the Lion accident particularly the part relating to the previous flight, it occurs to me that following a flight with major instrument discrepancies, continuous stick shaker and multiple uncommanded stab trim movements it might have been appropriate to add something to the tech log entries like "aircraft unfit for revenue flight pending maintenance action".
Would that have prevented the accident?
Well, perhaps the manufacturer would have been consulted for a more in depth assessment than a line engineer could provide. So who knows?
The nuclear option is sometimes the right choice.

[BRE]

Originally Posted by CONSO

and some more data

https://www.theatlantic.com/notes/20...37-max/584791/


https://asrs.arc.nasa.gov/overview/database.html

Two cases where the aircraft pointed down just after AP engagement, and crew were aware that the augmentation system was only active with flaps 0 and no AP. Couldn't figure out a setup problem with the AP in either case.

So why did they report to the anonymous NASA system and not to their airline and the FAA to have the QAR pulled right away and conserve date?

[FCeng84]

Originally Posted by DaveReidUK

Are you referring to the AoA display on the PFD, or to a separate annunciator that isn't present at all on non-equipped aircraft?

I am not familiar with the AOA display layout so I am not sure if the AOA display option that Southwest has purchased is what you show on the PFD or another readout. My comment about displays was based on previous inputs by others on this forum. My comment about the display option not impacting control law logic is based on a number of sources - I am very confident in that.

[JamesT73J]

Originally Posted by EternalNY1

What about the mentions of speed being far too high, even while they were climbing to a safer altitude?

That isn't a CoG or trim issue ... ??

With the engines at takeoff thrust a low pitch angle would have the thing sledding along pretty quickly, I would guess. Especially if they weren't keeping an eye on it.

[GLAEDI]

Piece Found at Boeing 737 Crash Site Shows Jet Was Set to Dive

By
Alan LevinMarch 15, 2019, 12:06 AM EDTUpdated on March 15, 2019, 6:59 AM EDT

• Screw was said to be configured to put plane into a dive
• Downing of Boeing 737 Max in Ethiopia has grounded fleet

Boeing Suspends All 737 Max Aircraft Deliveries A screw-like device found in the wreckage of the Boeing Co. 737 Max 8 that crashed Sunday in Ethiopia has provided investigators with an early clue into what happened, as work begins in France to decode the black boxes recovered from the scene.

The so-called jackscrew, used to set the trim that raises and lowers the plane’s nose, indicates the jet was configured to dive, based on a preliminary review, according to a person familiar with the investigation. The evidence helped persuade U.S. regulators to ground the model, said the person, who requested anonymity to discuss the inquiry.

France’s aviation safety agency BEA received the cockpit voice and data recorders on Thursday for decoding, while investigators on the scene near Addis Ababa continue to sift through the plane’s wreckage. The second crash in five months has thrown Boeing into a crisis, sending the shares plunging and raising questions about the future of its best-selling jet.

Separately, the New York Times reported that doomed Ethiopian Airlines Flight 302 to Nairobi was in trouble almost immediately after takeoff as it lurched up and down by hundreds of feet at a time. The captain asked in a panicky voice to turn back only three minutes into the flight as the plane accelerated to abnormal speeds, the newspaper reported, citing a person who reviewed the jet’s air traffic communications.

"Break break, request back to home," he told air traffic controllers as they scrambled to divert two other flights approaching the airport. The aircraft had accelerated far beyond what is considered standard practice. All contact between air controllers and the aircraft was lost five minutes after it took off, the report said.

Read: Black Box Politics: How National Pride Intrudes on Crash Probes

Federal Aviation Administration chief Daniel Elwell on Wednesday cited unspecified evidence found at the crash scene as part of the justification for the agency to reverse course and temporarily halt flights of Boeing’s largest selling aircraft. Up until then, American regulators had held off even as nation after nation had grounded the model.

Boeing shares have lost 12 percent, or $28 billion in market value, since Ethiopian flight 302 went down on March 10. The shares were trading at $372.20 in early U.S. trading Friday, little changed from Thursday’s close.

Read more: Chart on Boeing’s drop in market value

The jackscrew, combined with a newly obtained satellite flight track of the plane, convinced the FAA that there were similarities to the Oct. 29 crash of the same Max model off the coast of Indonesia. In the earlier accident, a safety feature on the Boeing aircraft was repeatedly trying to put the plane into a dive as a result of a malfunction.

Read More: Black Box Politics: How National Pride Intrudes on Crash Probes

All 157 people aboard died after the plane crashed near Addis Ababa, Ethiopia’s capital. The jet’s flight recorders are in France, where they are being analyzed at the BEA’s laboratories. The agency posted a photo of the mangled hardware and has yet to comment on any progress on getting the data. “The investigation process has started in Paris,” Ethiopian Airlines said in a Twitter post on Friday.

[Sailvi767]

Originally Posted by MPN11

Would the reported high speed of the aircraft in the latter stages (383 kts, as cited upthread) go to explain the 'falling debris' mentioned by eyewitnesses? Could that speed have started to initiate hull breakup, or detaching of some other components?

No, at the density altitude they were at that speed would be well under VNE.

[MPN11]

Originally Posted by Sailvi767

No, at the density altitude they were at that speed would be well under VNE.

Thank you ... it was just a passing thought.

[pilotmike]

Quote:For comparison, Volkswagen lost over 60% due to their emission scandal. But this could be, and should be big if it's due to MCAS.

Originally Posted by Icarus2001

A ridiculous comparison. VW set out to deceive and cheat the emission testing for commercial gain. Boeing added a function to enhance safety when operating at the edge of the envelope, somewhere most crews should and will never be but perhaps a faulty sensor and lack of a second input has caught them out.
Just remember that the crew who flew the affected Lion Air aircraft the day before the fatal managed to land safely. There are trim cut outs, manual trim and electric trim all of which override MCAS inputs.

Quite the opposite; it is a very good comparison - the paralles are very clear to see.

VW had to build a car that could pass the emissions standards. They achieved, through cunning, for commercial gain. And it polluted more than it should have.
Boeing had to build an aircraft that could pass certification. They achieved, through cunning, for commercial gain. Evidence suggests it has killed more people than it should.

[Running Ridges]

Originally Posted by Sailvi767

No, at the density altitude they were at that speed would be well under VNE.

Really? From what I can see Vmo is 340kts on the -800, not sure about the MAX but can't imagine it's different
383kts TAS is 339kts EAS at 8000'

[slip and turn]

Originally Posted by EDML

1. I don‘t think it is possible to survive a flapless T/O at this density altitude and take off mass.

My thoughts too when I also started musing about why a possible first rotation seem to fail (where those first VS reports occurred 2/3rds along the runway, and which DaveReidUK is inclined to put aside pending further clues ) and then they seemed to use so much runway with no height gain, but at the lat/long of Capt Kremin's chosen 207kts GS datapoint (seemingly some 1700ft into the dirt), that dirt beyond the paved areas has already fallen perhaps 150 feet from the runway (according to Google Earth elevations). So it is no Courchevel, and no USS Gerald R. Ford, but the terrain beyond the runway with or without approach light towers, does perhaps offer a little launch ramp type forgiveness.

It is lucky for analysts, that by that point we have no less than 15 ADS-B "airborne" datapoints covering 80% of the available runway and all points without a hint of any spuriousness are located slap bang along the centreline of 07R. Clearly ET302 wasn't airborne at 93kts GS where the first airborne report became available, but that's no real mystery in itself. So thus far I do not question the accuracy of the ADS-B GPS locations reported. It is the altitudes, groundspeeds and vertical speeds which are more questionable, but not overly so. Indeed the altitudes reported along the middle of the runway do seem to reflect moderate undulations found in Google Earth. Whether Google Earth elevations are accurate along the runway is another story.

Originally Posted by EDML

2. Even if they did - after reaching 1000ft and 300kt everything is fine and they could have continued the flight. However, here the disaster started at this point of the flight.

... everything is fine?? Are we sure about that? Where for example do we reckon they actually reached 1000ft above anything until the last few datapoints of the FR24 data?? And on the same score please, DaveReidUK, what point are you calling rotation and what point are you calling 1050ft AAL?

[Sailvi767]

Originally Posted by boeingboy737

If there are any mx tech on here can you tell us if the Stab trim cut out switches are connected to the MCAS system ie will the switches in the cut out position actually stop the MCAS from trimming thanks

They remove all power from the trim motors and completely disable the system.

[DaveReidUK]

Originally Posted by slip and turn

And on the same score please, DaveReidUK, what point are you calling rotation and what point are you calling 1050ft AAL?

I believe rotation was at approximately the 05:38:47 datapoint (certainly before the next point at 05:38:50).

1050' AAL (8150' ADS-B altitude) was achieved by 05:39:50.

[Sailvi767]

Originally Posted by Running Ridges

Really? From what I can see Vmo is 340kts on the -800, not sure about the MAX but can't imagine it's different
383kts TAS is 339kts EAS at 8000'

Density altitude would have been above 10,000 feet at airport elevation. 11,000 feet if peak speed was at 1000 AGL

[.Scott]

If this is what it appears to be - a problem that will need to be addressed by changing firmware and perhaps hardware, then the MAXs may be grounded for weeks or months.
Flight firmware is not quickly developed and certified.

[derjodel]

Originally Posted by .Scott

If this is what it appears to be - a problem that will need to be addressed by changing firmware and perhaps hardware, then the MAXs may be grounded for weeks or months.
Flight firmware is not quickly developed and certified.

787 was grounded for a month and the solution was a simple cage. I'm 100% sure there is no simple software solution for MCAS. Remember, MCAS is required for (self) certification, so it needs to be there in certain conditions. But it simply can't be there with only two AOA sensors, no matter how you hack it. Whatever you do, it could happen that MCAS does't engage when it should -> hence no certification, or it does when it's deadly.

[slip and turn]

Originally Posted by DaveReidUK

I believe rotation was at approximately the 05:38:47 datapoint (certainly before the next point at 05:38:50).

OK so it is not until 17 or 20 secs later that you reckon the VS figures begin to read true? And given the airfield elevation 7625' you are deducting how many feet for the QNH1029 correction to convert the 1013hPa 8or 1013.25hPa or 29.92inHg as you will) ADS-B figures to AAL?

1050' AAL (8150' ADS-B altitude) was achieved by 05:39:50.

That implies you may have converted thus: 8150'-7625'+525'=1050'. Are you using 1029-1013.25=15.75 and 15.75hPa x 33.3'/hPa=525'? Because I would use 1029-1013.25=15.75 and 15.75hPa x 27.3'/hPa=430' and conclude that at the 05:39:50 datapoint ET302 was around 950' some odd AAL, but then I may have it all wrong if I am to adjust the rate up from 27.3 to 33.3 because we are well above sea level - if so, I missed it at school

[infrequentflyer789]

Originally Posted by Jo90

Having read (well skimmed) the interim report of the Lion accident particularly the part relating to the previous flight, it occurs to me that following a flight with major instrument discrepancies, continuous stick shaker and multiple uncommanded stab trim movements it might have been appropriate to add something to the tech log entries like "aircraft unfit for revenue flight pending maintenance action".
Would that have prevented the accident?

Maybe, maybe not. Remember, they did log uncommanded trim movements ("STS trimming wrong" - remember they had no knowledge of MCAS even existing) and maintenance action was taken before the last flight - it just didn't find or fix the real problem.

Also, even if it had prevented that accident, it wouldn't prevent one where the first crew that hits the problem cannot cope with it (and ET may well be that).

When trying to pin blame on crews, airlines, maintenance remember that the 737 MAX is a new variant of an existing type (lets restrict to the NG for comparison), same type certificate, same type rating, so similar that the only pilot training is apparently a powerpoint.

NG: ~7000 in service, 16 losses in >20 yrs
MAX: ~ 350 in service, 2 losses in <3 yrs

- same crews
- same training (modulo the powerpoint)
- same airlines
- same maintenance
- same procedures

MAX simply crashes more often, and there's a pattern (shortly after takeoff, flight control problems reported, uncontrolled dive). Even without any knowledge of MCAS you would have to say that there is something wrong with this aircraft and that it's something in the changes from the NG.

[clearedtocross]

System bugs are caused for three main reasons:
1. Bad Specs
2. Faulty implementatation
3. Incomplete tests and hasty correction of faults.

#1 is by far the worst because it affects #2 and #3 as well and may not be detected during the whole development process.What‘s worse is that in complex developments, this process is cascaded from one system to all of its subsystems.
So here we have an airplane design spec that was most likely not taking into account the aerodynamic behaviour of relocating the engines. I bet the problem was only detected after some test flying of the new airplane. So time runs out, a redesign of the aircraft is now impossible and so a software patch is called for to get better stall protection. The aircraft is not FBW and thus the triple redundancy and voting concept is neither required nor followed. And as all software engineers know, patches sometimes backfire because they have not been designed with the same care as the original system. Ask Bill Gates.

But the patched system is not self-contained, not isolated, it affects and is affected by a lot of other systems and components. If some of these sensors and systems feed wrong air-data, the result is unpredictable probably even for the inventors, but certainly for the poor pilots affected and for the majority of ppruners including me.

Now some of you say „hey that‘s just a little speed bump“, remain cool and switch some breakers and fly away serenely. Thats okay for the Chuck Yeagers and Neil Armstrongs. Those not having been trained as test pilots remain confused and try to fight a plane that does not behave as advertised and tries to kill you and your passengers. They might remember some FAA AD about trim anomalies when they are waiting to pass the pearly gates.

Conclusion: This patch is much worse than the original stability problem. Many aircraft pitch up to a stall if uncorrected after full power is applied, at least mine does. That‘s no issue. It baffles me that a device that can trim a jet fully nose-down without pilot input - caused by some erronous airdata - could ever be conceived and then certified and the facts about this box of Pandora not being passed on to the type-rated pilots and training facilities.

[EDML]

Originally Posted by slip and turn

... everything is fine?? Are we sure about that? Where for example do we reckon they actually reached 1000ft above anything until the last few datapoints of the FR24 data?? And on the same score please, DaveReidUK, what point are you calling rotation and what point are you calling 1050ft AAL?

Why not? If you accidently take off w/o flaps the critical moment is when you get out of ground effect. If you manage to accelerate out of that low energy state the aircraft is perfectly flyable. 300kt TAS at 11000ft DA is for sure a safe clean speed. All you might need to do is trim and pull into a normal climb angle.

After a flapless T/O the critical moments would be before reaching 1000ft and not thereafter.

[MELT]

[QUOTE

"So here we have an airplane design spec that was most likely not taking into account the aerodynamic behaviour of relocating the engines. I bet the problem was only detected after some test flying of the new airplane. So time runs out, a redesign of the aircraft is now impossible and so a software patch is called for to get better stall protection."


Clearedtocross, suspect you are spot on with this, and it wouldn't be the first time this has occurred either.

I think Boeing will be lucky to have the aircraft back in the air within 6 months.