Indonesian aircraft missing off Jakarta

[DaveReidUK]

That is my understanding as well, although I think it's more accurate to say that Mode S Enhanced Surveillance is the means by which the IAS is provided to ATC.

Yes, a suitably equipped Mode S secondary radar can interrogate the aircraft's transponder for a number of parameters, including IAS.

TAS and heading, too, among others.

[scifi]

Just getting back to the post concerning flying with Pitot Covers still attached. Is there a 'Jobsworth Culture' that prevents the tug operator from letting the flight crew know that the Covers are still attached..? These things would be dangling right in front of the Tug Driver's face.. I suppose there is too much of a seniority difference, for any useful safety conversation.
.

[A Squared]

Just getting back to the post concerning flying with Pitot Covers still attached. Is there a 'Jobsworth Culture' that prevents the tug operator from letting the flight crew know that the Covers are still attached..? These things would be dangling right in front of the Tug Driver's face.. I suppose there is too much of a seniority difference, for any useful safety conversation.
.

As cynical as I am, I am reluctant to believe that a tug operator in Brisbane would notice the pitot covers and choose not to say anything. People can fail to notice some pretty astonishing things. The "Gorilla in the Basketball game" video, for instance. I'm inclined to believe that the tug operator didn't notice them, despite them being right in front of his face. Perhaps I'm just being naive.

[Swedish Steve]

The Maintenance Release shows the time 12:40 UTC. The aircraft landed at 15:55 UTC (22:55 local time). Maybe the airworthy release was signed at 00:40 local time on 29th, but still only 1h45min to fix two malfunctions.
The Maintenance release was signed in DPS before that flight. It is not the maintenance release for the next flight from CGK. That is on the next tech log page.

[DaveReidUK]

As cynical as I am, I am reluctant to believe that a tug operator in Brisbane would notice the pitot covers and choose not to say anything. People can fail to notice some pretty astonishing things. The "Gorilla in the Basketball game" video, for instance. I'm inclined to believe that the tug operator didn't notice them, despite them being right in front of his face. Perhaps I'm just being naive.

From the Preliminary Report:

The pitot probe covers were fitted on the aircraft’s three pitot probes by one of the engineering support personnel, as it was his understanding this was normal practice. He later reported that he advised the operator’s maintenance engineer that pitot probe covers were fitted during a brief exchange discussing turnaround tasks, but that the maintenance engineer did not directly respond. The maintenance engineer later reported that he did not recall hearing the advice, and he did not make an entry in the aircraft’s technical log to record that the covers had been fitted.

The presence of the pitot covers was not detected by the operator’s maintenance engineer or captain during separate external aircraft inspections. The operator’s maintenance engineer boarded the aircraft during turnaround, and the engineering support personnel left the bay to attend to other aircraft. The pitot covers were not detected by ground handlers during pushback.

[Organfreak]

The point being, make it part of his/her job. It can't be bad to have a third check as SOP.

[A Squared]

From the Preliminary Report: The pitot covers were not detected by ground handlers during pushback.

Well, yes, I think that regardless of what the tug driver did or didn't do, I think we all would all expect that he wouldn't confess that he saw them and didn't say anything.

[Organfreak]

Why should he/she, if it wasn't part of his job description?

[DaveReidUK]

Why should he/she, if it wasn't part of his job description?

I sincerely hope that, with an attitude like that, you don't work anywhere near aircraft.

[Organfreak]

I sincerely hope that, with an attitude like that, you don't work anywhere near aircraft.

What I meant to say, Dave, is that without training, there's no reason for the person to know to look!

[The Bartender]

Those streamers are most likely too short to be in pushback-operators FOV.

[Slow and curious]

How relevant is the pitotcover anyway. If a missed pitotcover was the cause of UAS on the previous leg, then it sure would be known by now. I doubt that a missed pitotcover was the cause of their problems.

[c_coder]

Don’t most ATC units display data sent from the aircraft, not radar calculated ground speed? Genuine question.
Eurocat will do that if the data is available. The only systems in the region that I am aware of are Singapore and Ujung Pandang.

[A Squared]

How relevant is the pitotcover anyway. If a missed pitotcover was the cause of UAS on the previous leg, then it sure would be known by now. I doubt that a missed pitotcover was the cause of their problems.

Probably not very. The chances are pretty slim that a pitot cover is involved in the accident at hand.

[lomapaseo]

As David said anyone who actually worked around airliners would know this stuff.

I for one would challenge this assumption

Show me the data that confirms this

[Chris2303]

Another one to add to the death toll - a diver has died

https://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=12154241

[unworry]

Indonesian rescue diver dies while searching for Lion Air jet crash (https://www.abc.net.au/news/2018-11-03/indonesian-rescue-diver-dies-in-lion-air-jet-crash-search/10463266)An Indonesian rescue diver has died in the search for a passenger jet that crashed early this week near Jakarta, killing all 189 people on board, search and rescue agency Basarnas said on Saturday.

A sad reminder of the risks that rescue teams and first responders undertake. Condolences to his family and friends.

[gums]

Salute!

Gotta go with "SLOW" and "A^2. No pitot/static covers left on. The problem was there even before the flight before.

Pitot/static problem? Yep.
Trim system function with bad air data? Yep, or a strong maybe..
Mechanical failure leading to an extreme dive to impact? Don't know
++++++++++++++++++++++++
News media now claims the main fuselage has been detected, and the "pinger" or tone of one recording device has also been detected.

Gums sends.......

[judebrad]

A very interesting presentation from American Airlines back in the 90's called Children of Magenta -(you can search for this on google) described the over dependency on computers when things went wrong very quickly and not reacting by instinct due to lack of flying skills or part thereof. Also, possibly a loss of CRM skills since when under stress, you tend to revert to earlier behaviors without thinking. Could both flightcrew (since they were of different nationalities) loose precious time diagnosing the issue and flying the aircraft out of the situation(assuming the plane was flyable until the crash).

[DaveReidUK]

A very interesting presentation from American Airlines back in the 90's called Children of Magenta -(you can search for this on google) described the over dependency on computers when things went wrong very quickly and not reacting by instinct due to lack of flying skills or part thereof.

It's been referenced many times on PPRuNe over the years, but for anyone who hasn't seen it yet:

Children of the Magenta Line

I may be wrong, but I believe the late Captain Vanderburgh was the first to coin that phrase.

[Golden Rivit]

https://theaircurrent.com/aviation-safety/the-perilous-unreliability-of-lion-air-logs-floating-through-social-media/

[Centaurus]

Extract from the Aeroperu Boeing 757 CVR 1996 crash with static vents blocked (English translation)
https://web.archive.org/web/20030427083626/http:/www.avweb.com/news/safety/183038-1.html
One wonders if the Lion Air crew found themselves in the same state of confusion. Sensory overload can overwhelm rational actions every time.

[LEOCh]

As concerns the cause, it would seem to me relatively rare for several pitot systems to fail simultaneously. To note that the ias/alt pitot system is separate from the elevator pitot system, the first being located at the front of the A/C, the second on each side of the front base of the V/S. (Repeated) Simultaneous failure of both systems would IMO indicate something more structural then the pitots themselves.

As to the effect, in particular the "FEEL DIFF PRESS LT ILL" could be of particular relevance. The elevator feel computer provides simulated aerodynamic forces using airspeed (from the said elevator pitot system) and stabilizer position. Feel is transmitted to the control columns by the elevator feel and centering unit. To operate the feel system the elevator feel computer uses either hydraulic system A or B pressure, whichever is higher. When either hydraulic system or elevator feel pitot system fails, excessive differential hydraulic pressure is sensed in the elevator feel computer and the FEEL DIFF PRESS light illuminates.

I stand to be corrected, but if (barring hydraulic problems) the elevator feel and centering unit enters into a condition that triggers the FEEL DIFF PRESS annunciation (for whatever reason, either pitots or a more systemic failure, since in this case also the "main" pitot system could have been affected simultaneously), it would mean that particularly in manual flight the elevator inputs through the control columns could have a much different (greater) effect than normal. It would be interesting to know whether such inputs with a "dysfunctional" feel and centering unit could lead to upsets with an ultimate loss of control, which at relatively low altitude would be difficult to recover from in time.

Thanks Bru, am also operating on the assumption that the maintenance logs are genuine and the faults on the previous flight point are likely factors on the accident flight.

The FEEL DIFF PRESS light from the elevator feel system is very puzzling because (as you said) the pitot system is separate, and to my knowledge totally isolated from the ports/ADMs/ADIRUs at the front of the aircraft. I am assuming an actual large hydraulic pressure difference between systems A and B would lead to more fault indications than just the FEEL DIFF PRESS. One thing I can't find out is the static source for the elevator feel pitots, but this system should be in an unpressurised part of the plane and hence could just sample it's ambient surrounds to pair with it's pitot. So how could these problems be related?

On thing to consider is whether the STS (if operating on bad airspeed data) could effectively contaminate the feel system operation via the changes it makes to the stab trim. Stab trim position is an input to the elevator feel system along with airspeed from it's dedicated pitot system (which should have been working even with issues with the nose airspeed sensing systems). In this case the operation of the STS with bad airspeed is the major issue, with likely alteration of elevator feel a secondary (but likely very unhelpful) issue.

[FL11967]

Do the stats show that the Children of Magenta are crashing planes due to lack of manual flying skills? Are planes crashing on stormy 30 knots cross wind approaches? I would argue that that the pilots who flew AF447, Emirates 521, AA 8501, etc. could fly manual just fine. The problem was that they had no idea what the automation was doing when problems crop up. It's the sheer complexity of modern aircraft. Excellent in increasing air safety to unprecedented levels but has become incredibly complex for both "old school" and "magenta" drivers.

[Icarus2001]

AF447, Emirates 521, AA 8501, etc. could fly manual just fine. The problem was that they had no idea what the automation was doing when problems crop up. Well let's look at the Emirates B777 go round from touch down. Do you need a two day course to tell you to push the thrust levers forward if they do not move forward on their own? Or to check the engine gauges to confirm that the engines are spooling up after pressing TOGA? That is fundamental "pilot stuff" surely?

Isn't the point that if " they had no idea what the automation was doing" then they should hand fly? As you say "they could fly manual just fine".

I agree it is not too difficult to occasionally "get lost" in the automation modes, that is why there are disconnect buttons.

[parabellum]

If a pitot cover had been left on it should have been very obvious to the crew before they even got to 80kts on the take-off roll, surely?

[Onesixty2four]

"I would argue that that the pilots who flew AF447, Emirates 521, AA 8501, etc. could fly manual just fine."

The fact that these perfectly flyable aircraft crashed voids your statement.

[Organfreak]

Thanks for setting me straight you guys. No, I don't deal with airliners, but I learned a lot following the entire, sorry AF447 thread! Sorry for my ignorant remarks, I meant well.

[Capn Bloggs]

I would argue that that the pilots who flew AF447, Emirates 521, AA 8501, etc. could fly manual just fine.
?? Do you know what "flying" actually is or what it entails? It means looking at the flight and engine instruments, checking that the aeroplane is doing what you want, and if it is not, intervening with your hands, and feet to make it so. "Flying" also means being able to do it when startled or caught unawares. That did not happen in any of those prangs. That fact that you cannot see that, even with NO systems knowledge, each of those accidents would have not occurred had the PF just employed basic flying techniques indicates to me you do not understand the job.

The fact that these perfectly flyable aircraft crashed voids your statement.
No it doesn't. If pilots "could fly manual just fine" they wouldn't have crashed. That's the whole point. It is clear that some of you have no idea of the modern cockpit operates.

https://theaircurrent.com/aviation-s...-social-media/ (https://theaircurrent.com/aviation-safety/the-perilous-unreliability-of-lion-air-logs-floating-through-social-media/)
As for that, anybody who has half an idea (which is obviously not "Theaircurrent") would realise that all those docs, as shown, are legit but at various stages of the defect reporting and the rectification process. In other words, that whole article is a meaningless waste of time and effort. Please stop posting this stuff.

[Onesixty2four]

Originally Posted by 1624The fact that these perfectly flyable aircraft crashed voids your statement.No it doesn't. If pilots "could fly manual just fine" they wouldn't have crashed. That's the whole point. It is clear that some of you have no idea of the modern cockpit operates.


That was my point.

[LaissezPasser]

If a pitot cover had been left on it should have been very obvious to the crew before they even got to 80kts on the take-off roll, surely?
https://www.ntsb.gov/_layouts/ntsb.aviation/brief2.aspx?ev_id=20021127X05535&ntsbno=DCA03IA005&akey=1

[Icarus2001]

If a pitot cover had been left on it should have been very obvious to the crew before they even got to 80kts on the take-off roll, surely? Just like the Malaysia A330 on 18 July 2018 at Brisbane that became airborne with the covers on.

Which of course begs the questions...100 knots check? V1 Rotate? The crew acknowledged they had red SPEED flags on their PFD.

https://www.atsb.gov.au/publications/investigation_reports/2018/aair/ao-2018-053/

[JulioLS]

A summary of ATC discussions was posted on Tempo. My translation of what was published as follows.

06:21:23 Pilot made first contact with ATC. [Altitude 900ft]

06:21.53 Pilot reported flight control problems and asked for holding position at 5000ft. ATC gave permission.

06:22:57 Pilot asked the speed of the aircraft from ATC. ATC responded 332knots.

(Note: no mention of ground or air speed, the bahasa is "speed of the aircraft")

06:29:39 Recorded data that the aircraft left 5000 feet.

(Note: It isn't clear whether this is ATC comms or just an observation)

06:29.55 Pilot given permission to return to arrival using runway 25 because of the flight control problem.

06:31:35 Pilot requested return to point ESALA because of weather and not sure about the altitude of the aircraft. Pilot requested 3000ft clearance with other aircraft.

06:32:00 ATC asked whether the pilot was ready to return to the runway. There was no response.

06:33.30 ATC contacted Batik Air 6401 to look for the position of Lion Air.

[JulioLS]

FAMO;

The bahasa actually says he requested the "speed of the aircraft" (kecapataan pesawat). Not airspeed nor ground speed.

[AfricanSkies]

The crew reported 'flight control problems'.

They also asked for a speed from ATC.

Then crashed the aircraft in VMC in what appears to have been a high energy dive.

Looking at the Tech Log, pitot static snag and 'feel diff' snag.

Anyone here ever flown a 737 without the feel diff working? The controls are extremely sensitive, especially at high speed, very easy to overcontrol. 737s tuck easily, and this will get out of the box quick. Gums I agree, we're probably looking at a structural failure, caused by over controlling due to feel diff failure, caused by pitot static problems.

[vilas]

Which of course begs the questions...100 knots check? V1 Rotate? The crew acknowledged they had red SPEED flags on their PFD.
This is simply ridiculous piloting.

[wheels_down]

Looking at the Tech Log, pitot static snag and 'feel di
Anyone here ever flown a 737 without the feel diff working? The controls are extremely sensitive, especially at high speed, very easy to overcontrol. 737s tuck easily, and this will get out of the box quick. Gums I agree, we're probably looking at a structural failure, caused by over controlling due to feel diff failure, caused by pitot static problems.
There was no recovery at all in the dive which backs up the structural failure theory. They obviously had no control whatsoever in the high energy dive as considering the clear conditions (they would have seen the ocean floor approaching) there would have been some form of correction to avoid impact, but the numbers don’t show this.

There is a lot of talk about pitot gives giving incorrect readings but this still does not explain why it dropped like a rock in VMC. There would have been some form of correction on the way down.

[Derfred]

The crew reported 'flight control problems'.

They also asked for a speed from ATC.

Then crashed the aircraft in VMC in what appears to have been a high energy dive.

Looking at the Tech Log, pitot static snag and 'feel diff' snag.

Anyone here ever flown a 737 without the feel diff working? The controls are extremely sensitive, especially at high speed, very easy to overcontrol. 737s tuck easily, and this will get out of the box quick. Gums I agree, we're probably looking at a structural failure, caused by over controlling due to feel diff failure, caused by pitot static problems.

FEEL DIFF PRESS doesn’t necessarily mean no or even diminished elevator feel. It is most likely to mean a loss of dual redundancy due to an Elev Feel pitot blockage or a loss of Sys A or B pressure. In that case, elevator feel will continue to function normally.

It’s a good point though, if they did lose elev feel, it possibly could lead to LOC or structural damage if not managed carefully.

I am surprised, however, that a fault with main air data could also cause a feel diff press problem. I thought they were essentially independent. I only fly NG, not MAX.

So this is an interesting malfunction (the previous flight).

[73qanda]

Anyone here ever flown a 737 without the feel diff working? The controls are extremely sensitive, especially at high speed, very easy to overcontrol.
I’m not sure exactly what you are getting at here. I would have thought that an amber FEEL DIFF PRESS light indicates that either A or B hydraulics has failed ( clearly there would be other indications), or, the elevator pitot system has failed.
When you say “ without the feel diff working”, do you mean without the elevator feel computer working?
Cheers

[Nomad2]

Great advice given to me while flying the ERJ-145 many years ago, was to simply put the N1 needles to 12 O'clock if you are unsure of airspeed.
this gave a power setting that was pretty unlikely to induce an overspeed, but was enough to avert a stall as long as you flew roughly level. The thing would bumble along at about 200 knots if I remember correctly.
I think all aircraft could this sort of general advice, but I can also think of a few reasons why I've never seen it written down.

[bobdxb]

There was no recovery at all in the dive which backs up the structural failure theory. They obviously had no control whatsoever in the high energy dive as considering the clear conditions (they would have seen the ocean floor approaching) there would have been some form of correction to avoid impact, but the numbers don’t show this.

There is a lot of talk about pitot gives giving incorrect readings but this still does not explain why it dropped like a rock in VMC. There would have been some form of correction on the way down.


I agree with you, it should have been some kind of correction. However when I think of extreme rate of descent and speed of jack screw I could imagine how little they were able to do...
https://youtu.be/rxPa9A-k2xY

[matkat]

From the Preliminary Report:
The fact that the installation of the pitot covers was not entered in the tech log was the final 'hole to line up' when I worked the line it was always policy to enter such into the tech log gear pins being the other, I am in no way saying that this system was in any way infallible but is certainly a good idea.

[A Squared]

The fact that the installation of the pitot covers was not entered in the tech log was the final 'hole to line up' when I worked the line it was always policy to enter such into the tech log gear pins being the other, I am in no way saying that this system was in any way infallible but is certainly a good idea.

My read of that report is that it was policy in this case as well, but that there was a breakdown in communications between the guy who installed the covers and the guy who would have entered that in the log.

[Triskelle]

SLF (meteorologist) here. Sad to read about all of the incidents related to unreliable airspeed readings. However, I've seen reference to 'GPS altitude' in this thread so GPS data is obviously available to the aircraft systems - would it be desirable to have a small display of GPS ground-speed or 3D speed-through-space available, and perhaps a rough ISA-derived Mach number, incorporated into the flight display panel to provided some reference in the case of having to deal with a UAS situation?

[DaveReidUK]

would it be desirable to have a small display of GPS ground-speed or 3D speed-through-space available

737 Max Navigation Display:

https://cimg0.ibsrv.net/gimg/pprune.org-vbulletin/732x544/737_max_navigation_display_b6d65f7c2d9006ce04f0e8682bb002568 692bae4.jpg

[edmundronald]

Do the stats show that the Children of Magenta are crashing planes due to lack of manual flying skills? Are planes crashing on stormy 30 knots cross wind approaches? I would argue that that the pilots who flew AF447, Emirates 521, AA 8501, etc. could fly manual just fine. The problem was that they had no idea what the automation was doing when problems crop up. It's the sheer complexity of modern aircraft. Excellent in increasing air safety to unprecedented levels but has become incredibly complex for both "old school" and "magenta" drivers.


Indeed, one could argue that the AF447 accident was due to cognitive overload - the pilots simply got way behind the plane, lost any understanding of what was happening and stalled. The fact that the pilots stalled the plane is the conclusion of the report - not conjecture on my part, but it could be argued that if they had more time, to arrive at an understanding of the root cause of the issue - UAS or erroneous airspeed, they would have done better

An hour here and there of added training isn't going to turn commercial pilots into test pilots. Which is essentially what they are asked to be when they end up outside the automated flying envelope.

It is possible that the flight engineer on the old airliners would have been better equipped mentally to handle the diagnosis of the malfunction and tell pilots how to behave. But while he's been removed from the cockpit, Hal has not quite been able to replace him.

So an interesting question which no one is willing to ask is whether the current generation of pilots actually have the intellectual abilities to troubleshoot the automation at the speeds at which incidents happen. Nobody would expect a surgeon to be of average intellectual ability - but his failure to correct a problem as it develops will only imperil one person's life.

My feeling is that the safety improvements to the mechanics of airliners have already taken place to the point of diminishing returns, and that improving automation and training is where the safety issues now lie.

Edmund

[A Squared]

SLF (meteorologist) here. Sad to read about all of the incidents related to unreliable airspeed readings. However, I've seen reference to 'GPS altitude' in this thread so GPS data is obviously available to the aircraft systems - would it be desirable to have a small display of GPS ground-speed or 3D speed-through-space available, and perhaps a rough ISA-derived Mach number, incorporated into the flight display panel to provided some reference in the case of having to deal with a UAS situation?

Any aircraft equipped with a GPS based navigation system will have a display of the GPS derived groundspeed available to the pilot.

[Chu Chu]

Take this thought from an SLF for what it's worth, but when I read that the pilots could have saved the aircraft by looking up pitch and power settings on a chart, I ask what about that couldn't be done by a computer. Of course, the computer couldn't land the aircraft on pitch and power (or at least I don't think it could). But it seems a lot safer to hand control back to the pilots with the aircraft in a stable climb (in this case), and let them take things from there.

[Capn Bloggs]

I really am worried that a significant number of posters here who seem have no idea of what it is like to fly and airliner and so do not understand the priorities and the skills required to do the job but are now casting judgement on the very profession.
Indeed, one could argue that the AF447 accident was due to cognitive overload - the pilots simply got way behind the plane, lost any understanding of what was happening and stalled. The fact that the pilots stalled the plane is the conclusion of the report - not conjecture on my part, but it could be argued that if they had more time, to arrive at an understanding of the root cause of the issue - UAS or erroneous airspeed, they would have done better
No. Those guys probably would have got a high pass in a systems exam BUT THEY COULDN'T FLY. Think about it: you have full power, 10° Nose Up and you're descending at 10,000ft/min with the speed coming and going, with the occasional stick shaker. What do you reckon is happening?? Granted they weren't helped by a poxy stab trim system, a silly stall warning system and a misleading flight director, but hey, we've stalled it Bloggs, get the nose down!!

An hour here and there of added training isn't going to turn commercial pilots into test pilots. Which is essentially what they are asked to be when they end up outside the automated flying envelope.
Yes it will! You can get to practice exactly how to fly out of crazy scenarios because the engineers are incapable of thinking of everything. Couple that with more hand-flying and you'll have pilots who can filter out all the distraction and FLY THE AEROPLANE until they sort out what is going on.

It is possible that the flight engineer on the old airliners would have been better equipped mentally to handle the diagnosis of the malfunction and tell pilots how to behave. But while he's been removed from the cockpit, Hal has not quite been able to replace him.
Seriously? What would an engineer have said in the accidents mentioned, AF 447, Emirates 421 and AA 8501 (and a host of other LOC prangs?). Excuse me skip, I think we've stalled? How would he/she know? Do you want them to do a flying course as well?

So an interesting question which no one is willing to ask is whether the current generation of pilots actually have the intellectual abilities to troubleshoot the automation at the speeds at which incidents happen. Nobody would expect a surgeon to be of average intellectual ability - but his failure to correct a problem as it develops will only imperil one person's life.
I would suggest too much emphasis is being placed on bookwork (probably because it is easy to study and test). The skill, the art of flying, the very ability to ignore the rubbish and fly your aeroplane is the bit that needs improvement. Contrary to what some of you think, this is not rocket science. But it does require a certain skill that you cannot learn from a book. Perhaps that is the reason some of you are hiding behind knowing your FCOM and OM back to front and all will be well. Well I'm sorry, that's not the way aviation works, and if you were sitting in the left hand seat you'd know what I was talking about.

My feeling is that the safety improvements to the mechanics of airliners have already taken place to the point of diminishing returns, and that improving automation and training is where the safety issues now lie.
If you mean improving the automation so that the pilot is not handed a bag of #$%^ when the automation spits the dummy, I'm all for it. And if you mean more pilot-handling skill training in the Sim, then I am also all for it.

And another thing. For all the prangs that occur, there are probably hundreds (if not thousands) of other non-prangs where the systems have lost the plot and the pilots have saved the day. I think I read there were 30 AF447-type incidents alone before the actual crash, all saved by the pilots.

[ATC Watcher]

Very good remarks edmundronald (https://www.pprune.org/members/234980-edmundronald) I could not agree more. Same reasoning for us Controllers, ability to recover automation failures is almost nil. The good old adage : automation "de-skills" is not only correct but frightening since it is this de-skilled " magenta" generation which is currently training the young ones entering the profession(s).
On the ability for ATC to see the mode S parameters , ( the so called Enhanced FMS parameters) my center use them very successfully since a few years . The parameters downlinked are IAS and Mach number, Magnetic heading , vertical speed ( but very unreliable ) and the selected altitude ( the one the crew enters on the FMS) this last feature has almost eliminated levels busts, as a warning comes off on the ATC display when it differs from cleared FL by ATC .
As to the vertical speed , it is very unreliable due accuracy of mode S (25 ft variations) it is common that short variations , especially in turbulence can send messages with 10.000ft VS. This is most probably why we see 30.000ft on the ADS-B diagram posted earlier. I would
think it might be a brief acceleration, but not a continuous descent at that rate . This is why ADS-B readouts , and especially those from FR24, are not a good source for incident/accident investigation. To get a general idea , yes, but not much more.

[A Squared]

Take this thought from an SLF for what it's worth, but when I read that the pilots could have saved the aircraft by looking up pitch and power settings on a chart, I ask what about that couldn't be done by a computer.

Well, one of the lines of speculation is that the handling problems were exacerbated by the computer control of an automated trim system, as a result of erroneous data being fed into the computer. What you're proposing is to have that same computer (whcih is making the problem worse, based on bad data input), take over flying the airplane, and fix the problems that it is creating ... based on that same bad data that is causing the problem. See how that all gets kinda circular?

[DaveReidUK]

As to the vertical speed , it is very unreliable due accuracy of mode S (25 ft variations) it is common that short variations, especially in turbulence can send messages with 10.000ft VS. This is most probably why we see 30.000ft on the ADS-B diagram posted earlier. I would think it might be a brief acceleration, but not a continuous descent at that rate.

Yes, the VRate parameter of ADS-B is very unreliable for the reasons you state, but sadly it's clear simply from the altitude profile of the last recorded 15 seconds or so of the flight that the ROD would have been well into 5 figures.

[Capn Bloggs]

https://www.abc.net.au/news/2018-11-04/lion-air-crashed-plane-flight-recorder-69-hours-data-recovered/10464204
Lion Air crash: Investigators recover 69 hours of flight data from black boxUpdated about an hour ago; Sun 4 Nov 2018, 8:29pmInvestigators have retrieved hours of data from the flight recorder of the Lion Air jet that crashed off Jakarta on October 29, killing 189 people on board.The news came as Indonesian authorities on Sunday extended the search at sea for victims and debris.

National Transportation Safety Committee deputy chairman Haryo Satmiko told a news conference that 69 hours of flight data was downloaded from the recorder including its fatal flight.

The Boeing 737 MAX 8 jet crashed just minutes after take-off from Jakarta on October 29 in the country's worst airline disaster since 1997.

The flight data recorder was recovered by divers on Thursday in damaged condition and investigators said it required special handling to retrieve its information.

The second black box — a cockpit voice recorder — has not been recovered but searchers are focusing on a particular area based on a weak locator signal.

"From here we will analyse what happened to that flight," Nurcahyo Utomo, head of Indonesia's transportation safety committee, told reporters.

Analysis of the data and a recovered aircraft landing gear and engine will begin on Monday and information will be passed to police if needed, Mr Utomo said.

[DaveReidUK]

Underwater footage shows debris of Lion Air jet crash (https://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=12153667)

[SLFinAZ]

To me this all boils down to a very simple set of questions. We have an airframe with a known set of technical issues which were easily managed on the previous flight. Those known issues should have generated a very specific review of certain procedures and been addressed in detail in the preflight planning/brief.

So...

1) were the memory items and checklist briefed prior to takeoff as would be expected?
2) was the problem identified in a timely manner and were the memory items and checklist preformed in a timely manner?


If the airplane was in fact being flown utilizing pitch and power and suffered a loss of control then we have one set of issues. If an attempt to re-engage the AP was made you have a totally different scenario. Do we have any clear information on how the previous flight was conducted after recovery? Was the AP reengaged or did the FO
hand fly the plane? What would the normal intent be for the PIC in these circumstances given the previous issues. If you (the professional captains here) were conducting the preflight brief would your stated intent be to return in the event of a technical issue or to troubleshoot and continue? To me the logical mindset would be to return but
what is the SOP here? Would the thinking be identical to the previous flight where the issue was addressed very quickly and the PIC determined that it was both safe and prudent to continue the flight as scheduled?

How long did the trouble shooting take and what was the configuration for the remainder of the flight (was it flown raw data?). Would this information be readily available to the crew in this flight? Was there a pressure to meet this standard and continue? From what I recall the previous flight declared an emergency but then pressed on. Could the
same scenario have been playing out where even though a request to return was made that there was no real intent and that the upset occurred when they attempted to duplicate the previous flights configuration?

Obviously something catastrophic occurred very quickly. If they felt they had addressed the issue and had the intent to press on would attempting to re-engage the AP and then having it spit the bit be more likely or would manually flying at the prescribed settings and being distracted while trying to troubleshoot be more likely? I'm guessing that the CVR will show that
they were trying to continue the flight instead of having a 100% focus on configuring the plane for a return.

[Cloudtopper]

Underwater footage shows debris of Lion Air jet crash (https://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=12153667)

Looking at this underwater footage , considering the depth of the water already the jet is becoming covered with the seafloor spreading.
MH370 certainly is substantially in a worse off position after a number of years in deeper waters and ocean currents. .

[Smott999]

now seeing rpts on cnn that they have lost the ping signal from CVR....getting buried ?

[Cloudtopper]

now seeing rpts on cnn that they have lost the ping signal from CVR....getting buried ?

Highly improbable as the battery should be designed to last 30 days . Technical name being the underwater locator beacon. {ULB}

[hans brinker]

Yes, a suitably equipped Mode S secondary radar can interrogate the aircraft's transponder for a number of parameters, including IAS.

TAS and heading, too, among others.

While that is true, I doubt the local controller had the equipment to display those parameters.

[M68]

Underwater footage shows debris of Lion Air jet crash

The text below the video is also interesting.

Regarding the problems during the previous flight and the ensuing maintenance I have some (outsider) questions.
Can one assume that, via some type of communication, the maintenance crew was given a detailed account of how severely that flight was affected by whatever technical fault that occurred?
Or would they have only had a piece of paper with a couple of short fault descriptions at hand?

[RatherBeFlying]

The likelihood of a blocked pitot depends on how industrious the local bugs are, but pitots blocked by insects are rare in temperate climates. It could be quite different in the tropics.

In this case we have pitots mounted on the fin to provide data to the STS, which leads to questions:

Are covers mounted?
Are STS pitots inspected pre flight?

Most likely a mobile platform would be needed.

Static ports are commonly covered for maintenance and testing. Aero Peru is just one example of how badly that can turn out in flight.

It's possible that the front pitot-static system was functional while the STS system was not, or vice versa. The confusion that might produce can only be imagined.

The tendency is that PF will believe his own airspeed over the others. It takes some serious CRM to work out which airspeed, if any, is the good one when one or more are bad.

[armchairpilot94116]

My bet would be the crew was not briefed and was not aware of the previous flight’s issues. And that the previous flight returned to normalcy after it gained altitude and that crew continued to destination and made a report

The plane was given a quick look and nothing of substance found and put back in service

When China Airlines had a spate of accidents back in the day I believe they hired Lufthansa to help them get the airline back in shape

Lion could use expertise from a company like JetBlue or Southwest to get their operations in order

Could be pilots are not trained well enough to handle various emergencies and perhaps there are punishments for emergency landings that were later found to not be needed

There are many issues to look at at Lion me thinks

[filejw]

My bet would be the crew was not briefed and was not aware of the previous flight’s issues. And that the previous flight returned to normalcy after it gained altitude and that crew continued to destination and made a report

The plane was given a quick look and nothing of substance found and put back in service


I find it hard to believe a crew even an inept one wouldn’t take a look at the logbook.

[Smott999]

an engineer on the flight?

[Eric Janson]

There are many issues to look at at Lion me thinks


Given their appalling incident/accident record the question is why they were allowed to continue operating at all.

Any Western Airline with a similar record would have had their AOC cancelled imho.

Plenty of questions for the CAA who appeared to have turned a blind eye to what was going on.

[DaveReidUK]

And didn't the have an engineer on the flight?

Yes, as you would know if you read the thread.

And they likely had a doctor, an accountant, a banker and a travelling salesman, too. What's your point ?

"engineer on the flight" < > "flight engineer". What difference would you expect the flying spanner in Row 23 to make to the outcome ?

[Smott999]

I did indeed mean “flight/maintenance engineer” as mentioned up-thread per avherald, placed onboard as “anticipatory measure”.
....mostly to rebut the notion that FC had not read the log or been prepared for similar issues to the prior flight.

[Longtimer]

Seems that some data has been recovered:Lion Air crash: Investigators recover 69 hours of flight data from black boxUpdated about 2 hours agoSun 4 Nov 2018, 7:53am https://www.abc.net.au/news/image/10452472-3x2-340x227.jpg (https://www.abc.net.au/news/2018-10-31/indonesian-navy-retrieves-from-lion-air-plane-crash-1/10452482)
Photo: Indonesian navy frogmen try to retrieve debris from the water during a search operation. (AP: Tatan Syuflana) (https://www.abc.net.au/news/2018-10-31/indonesian-navy-retrieves-from-lion-air-plane-crash-1/10452482)Related Story: Doomed Lion Air plane probably found at bottom of Java Sea, says Indonesian military (https://www.abc.net.au/news/2018-10-31/lion-air-plane-possible-location-found/10451774)Related Story: Crashed plane was brand new, but had 'technical issue' on previous flight (https://www.abc.net.au/news/2018-10-30/lion-air-plane-was-new-had-technical-issue-previous-flight/10445270)Related Story: Indonesian rescue diver dies while searching for victims of Lion Air jet crash (https://www.abc.net.au/news/2018-11-03/indonesian-rescue-diver-dies-in-lion-air-jet-crash-search/10463266)Investigators have retrieved hours of data from the flight recorder of the Lion Air jet that crashed off Jakarta on October 29, killing 189 people on board.Key points:

Fourteen of 189 victims identified from recovered remains
Search for victims extended by three days
Investigators still searching for second black box



The news came as Indonesian authorities on Sunday extended the search at sea for victims and debris.

National Transportation Safety Committee deputy chairman Haryo Satmiko told a news conference that 69 hours of flight data was downloaded from the recorder including its fatal flight.

The Boeing 737 MAX 8 jet crashed just minutes after take-off from Jakarta on October 29 (https://www.abc.net.au/news/2018-10-29/lion-air-passenger-plane-crashes-after-taking-off-from-jakarta/10441848) in the country's worst airline disaster since 1997.

The flight data recorder was recovered by divers on Thursday in damaged condition and investigators said it required special handling to retrieve its information.

The second black box — a cockpit voice recorder — has not been recovered but searchers are focusing on a particular area based on a weak locator signal.

"From here we will analyse what happened to that flight," Nurcahyo Utomo, head of Indonesia's transportation safety committee, told reporters.

Analysis of the data and a recovered aircraft landing gear and engine will begin on Monday and information will be passed to police if needed, Mr Utomo said.. Video: Black box retrieved from crashed Lion Air jet, Indonesian media says (ABC News) (https://www.abc.net.au/news/2018-11-01/reports-say-black-box-retrieved-from-lion-air-wreck/10457050)Search extended by three daysThe National Search and Rescue Agency chief Muhammad Syaugi said on Sunday the search operation, now in its seventh day and involving hundreds of personnel and dozens of ships, would continue for another three days.

Mr Syaugi paid tribute to a volunteer diver, Syahrul Anto, who died during the search effort (https://www.abc.net.au/news/2018-11-03/indonesian-rescue-diver-dies-in-lion-air-jet-crash-search/10463266) on Friday. https://www.abc.net.au/news/image/10463272-3x2-340x227.jpg (https://www.abc.net.au/news/2018-11-03/indonesian-diver-syachrul-anto-killed-while-searching-for-lion/10463274)
Photo: The search and rescue agency posted this photographic tribute to Syachrul Anto on its Instagram account. (Supplied: Instagram @sar_nasional) (https://www.abc.net.au/news/2018-11-03/indonesian-diver-syachrul-anto-killed-while-searching-for-lion/10463274)

The family of the 48-year-old refused an autopsy and he was buried on Saturday in Surabaya.

As of Sunday a total of 105 body bags, few containing intact remains, had been recovered and handed to police for forensic identification, yet only 14 victims had been identified.

"I'm sure the total will increase," Mr Syaugi said, adding remains were also now washing up on land.

The second black box is thought to be around 50 metres from the main search area, where the water is only 30 metres deep, but ocean currents and mud on the sea bed that is more than a metre deep have complicated search efforts.

Mr Syaugi said a considerable amount of aircraft "skin" was found on the sea floor but not a large intact part of its fuselage as he had indicated was possible on Saturday.https://www.abc.net.au/news/image/10464216-3x2-700x467.jpg (https://www.abc.net.au/news/2018-11-04/indonesia-investigators-inspect-machinery-from-fatal-lion-air-f/10464230)
Photo: Officials inspect an engine recovered the from crashed Lion Air jet. (AP: Achmad Ibrahim) (https://www.abc.net.au/news/2018-11-04/indonesia-investigators-inspect-machinery-from-fatal-lion-air-f/10464230)Patchy safety recordThe pilot of flight JT610 had asked for, and received, permission to turn back to Jakarta, but what went wrong remains a mystery.A long list of air safety incidents (https://www.abc.net.au/news/2018-10-30/lion-air-tragedy-latest-in-long-list-of-indonesia-incidents/10445326)https://www.abc.net.au/cm/lb/10445502/data/lion-air-custom-image-data.jpg (https://www.abc.net.au/news/2018-10-30/lion-air-tragedy-latest-in-long-list-of-indonesia-incidents/10445326)
The sadness in the Lion Air crash is that no-one would really be shocked by it — the Indonesian aviation sector has a bad reputation for good reason, writes former Indonesian correspondent Samantha Hawley. (https://www.abc.net.au/news/2018-10-30/lion-air-tragedy-latest-in-long-list-of-indonesia-incidents/10445326)

Flight tracking websites show the plane had erratic speed and altitude during its fatal 13-minute flight and a previous flight the day before from Bali to Jakarta.

Passengers on the Bali flight reported terrifying descents (https://www.abc.net.au/news/2018-10-30/lion-air-plane-was-new-had-technical-issue-previous-flight/10445270) and in both cases the different cockpit crews requested to return to their departure airport shortly after take-off.

Lion Air has claimed a technical problem was fixed after the Bali fight.

The first crash of a Boeing 737 MAX is the focus of scrutiny by the global aviation industry.

Preliminary findings of the investigation are expected to be made public after 30 days.

Indonesia is one of the world's fastest-growing aviation markets but its safety record has been patchy.

The Lion Air crash is the worst airline disaster in Indonesia since 1997, when 234 people died on a Garuda flight near Medan.

In December 2014, an AirAsia flight from Surabaya to Singapore plunged into the sea, killing all 162 on board.

Its transport safety panel investigated 137 serious aviation incidents from 2012 to 2017.

"There's still a lot we need to improve," Air Transportation Director General Pramintohadi Sukarno said at a press conference on Saturday, referring to safety rules.

AP/Reuters

[DaveReidUK]

I did indeed mean “flight/maintenance engineer” as mentioned up-thread per avherald, placed onboard as “anticipatory measure”.....mostly to rebut the notion that FC had not read the log or been prepared for similar issues to the prior flight.
Ah, I get your point.

The horrifying part is that you may well be right - that someone in the organisation was worried that the crew might find themselves with a barely controllable aircraft for the second sector in a row.

[TURIN]

Or that he was on board in the F/D jumpseat to observe any anomaly and help diagnose the fault. Been there, done it.

[JulioLS]

edmundronald;

I think the pilots on the previous leg, from DPS to CKG, had enough nouse to fly their way out of the problem manually.....

[JulioLS]

Well, one of the lines of speculation is that the handling problems were exacerbated by the computer control of an automated trim system, as a result of erroneous data being fed into the computer. What you're proposing is to have that same computer (whcih is making the problem worse, based on bad data input), take over flying the airplane, and fix the problems that it is creating ... based on that same bad data that is causing the problem. See how that all gets kinda circular?

I don't think he was saying that. Rather, I think he was saying that when the computer blows a gasket because of erroneous speed and alt data, it should revert to a basic mode of ignoring the inputs and just reverting to thrust and pitch (or lets say AoA). Nice idea but how does this computer know the pitch or AoA? Sometimes a pilot is a better option....

[Ian W]

Well, one of the lines of speculation is that the handling problems were exacerbated by the computer control of an automated trim system, as a result of erroneous data being fed into the computer. What you're proposing is to have that same computer (whcih is making the problem worse, based on bad data input), take over flying the airplane, and fix the problems that it is creating ... based on that same bad data that is causing the problem. See how that all gets kinda circular?

'The computer' (possibly several all working together in a network) already knows that there is a problem with the pressure instruments as the symptoms are reasonably obvious and can be diagnosed 'by the computer' with no problem, except that nobody has asked the software designer/architect/analyst to do that. The reliance has always been on handing the bag of bolts to the crew with a cryptic message or three together with aural alerts that might assist or confuse.
A system could easily alert that GPS alt changes mismatch pressure altitude change and offer to provide GPS altitude as a reference an on altimeter. Yes this does not match pressure altitude but is more accurate measuring vertical distance and rate of climb and descent. The much derided magenta line is generated by 'the computer' which also knows it in 4 dimensions how fast the aircraft is traveling along it and whether the aircraft is above or below it. 'The computer' in short could disregard the pressure instruments and just follow the magenta line in all 4 dimensions. It could even generate a new magenta line to the appropriate runway threshold and fly a recovery. Yes it may be hunting a little but it will know the approximate engine settings and then work from that reference. 'The computer' would then be doing the flying the aircraft by reference to the surface in the way that a pilot could do if that pilot stops trying to make sense of unreliable instruments and just looks out of the window disregards the instruments and flies by setting pitch and power. (A repeated mantra during the AF447 thread)

Another way of putting that is first thing to do is aviate - not try to solve system problems. 'The computer' could be designed to do that too. Perhaps it should be.

[Machinbird]

Good report out of Indonesia above. Good flow of information.
Regarding the flightmech onboard, it would be interesting to know if he was specialized in a particular area and where he might have been seated-cockpit or cabin.
Regarding implementation of pitch and power by the crew, I don't think so. From FR24 data, the aircraft was pretty much accelerating/overpowered throughout.

If I was airborne and found out that I was now a test pilot, flying an aircraft that was not performing at all like it is supposed to, I would try to maintain the airspeed close to where I first found the problem, and then move cautiously toward the most forgiving portion of the flight envelope considering the current aircraft configuration.
Just my 2 cents from a steam gauge era viewpoint.

[DaveReidUK]

Or that he was on board in the F/D jumpseat to observe any anomaly and help diagnose the fault.

Yes, that would work.

Oh, hang on ...

[IcePack]

Good post Capn Bloggs. Trouble is us pilots spent so many years dumbing down our profession that everyone thinks they can do it. This includes the owners & management hence recruit anyone especially those with money. The schools being commercial operations are very loath to fail those candidates without flying ability as they would loose students. Unfortunately not every one has the aptitude to be a pilot, in the true sense of the word even those that think they do. Quote “Fly the d** Arroplane & don’t over stress it. Get your cockpit management in place (CRM) & get the other guy to diagnose. If you want to confirm what he thinks hand him control & cross check his thoughts. It will be taking 80 to 90 % of your cognitive ability to control an “erroneont” aeroplane.

[JulioLS]

SLFinAZ;

From what I read (in Indonesian). The previous flight (DPS to CKG) requested to return. But killed the systems and hand flew it to Jakarta. They did not return to DPS. I assume they dealt with the situation, got control of the aircraft manually, and decided to continue. But that is guesswork.

[Eyes only]

Or that he was on board in the F/D jumpseat to observe any anomaly and help diagnose the fault. Been there, done it.

Of simply that the mechanics at the outport have not been trained up on the new MAX computer systems.

[A Squared]

edmundronald;

I think the pilots on the previous leg, from DPS to CKG, had enough nouse to fly their way out of the problem manually.....

Or perhaps the problem manifested itself in a more severe and uncontrollable manner than it did on the previous flight.

[DaveReidUK]

Of simply that the mechanics at the outport have not been trained up on the new MAX computer systems.

Essentially the issue is whether the airline was being disingenuous when (according to Avherald) it denied that the presence of the engineer was connected with the problems on the previous sector.

As previously posted, I find it hard to believe that a type that has been in service with the operator for nearly a year and a half, flying on a route that gets 6 daily rotations with the type, needed to carry a flying spanner just to sign off the aircraft at the outstation.

[Smott999]

I vote for airline disingenuous.
But it sure is troubling to think that the FC w engineer, presumably fully briefed on/even anticipating a particular problem, were still overcome. Assuming the issue was the same as prior flight of course.

[silverstrata]

Well, one of the lines of speculation is that the handling problems were exacerbated by the computer control of an automated trim system, as a result of erroneous data being fed into the computer.

The term ‘computer’ is somewhat overstating the technology in the speed-trim system. It is a couple of 286 processors, based upon a Sinclair ZX Spectrum architecture.

Silver

[Rananim]

To me this all boils down to a very simple set of questions. We have an airframe with a known set of technical issues which were easily managed on the previous flight. Those known issues should have generated a very specific review of certain procedures and been addressed in detail in the preflight planning/brief.

So...

1) were the memory items and checklist briefed prior to takeoff as would be expected?
2) was the problem identified in a timely manner and were the memory items and checklist preformed in a timely manner?



We MUST assume that :
a)the accident crew were aware of the previous flights UAS because it was written up in the tech log and would prohibit that Commanders acceptance of the
aircraft unless it had been signed off by a licensed engineer.When the accident Captain signs for the aircraft,he acknowledges reading the write up by the previous commander and the corrective action taken by the engineer.He must do this to accept the aircraft.

We CAN REASONABLY assume that:
a)The accident crew would have given special attention to UAS during the pre-flight briefing.They would have reviewed memory items and/or a plan of action.
b)The accident crew would have tried to obtain first hand information from the previous crew if possible(phone)
c)The flying spanner was added to the accident crew because of the tech issue.Lionair is a big airline and will have engineers based at most destinations.
d)The accident crew would have discussed the absolute need NOT to take a known pitot static anomaly into the air,of the need to abort the takeoff if ASIs diasgree at 80 knots.
e)The fact that they did not abort the takeoff implies strongly that the UAS was undiscoverable on takeoff.Prime suspect static vent(s).

We CAN HOPEFULLY assume:
a)Both accident crew members had been trained in UAS events in the simulator on one or more occasions in their flying career.
b)that both crew members knew verbatim the UAS memory items and of the absolute need to disengage ALL AUTOMATION and recognize that there is a mismatch between reality and perception and fly the plane using common sense attitude/thrust combinations.
c)That the crew would have sufficient lateral thinking to disengage any system fed by ADIRU false data that might conflict with their ability to control the aircraft.eg STS.The pilots see/hear the trim wheel spinning.They know or should know it is fed via AP stab trim motor.They know where the AP stab trim cutout switch is.

We can NEVER assume:
a)that the startle effect in all non normal situations will be controlled and handled well by a crew.The longer the startle effect lasts the more chance for loss of muscle memory,cognitive thinking,and onset of panic.

[Vessbot]

We MUST assume that :
a)the accident crew were aware of the previous flights UAS because it was written up in the tech log and would prohibit that Commanders acceptance of the
aircraft unless it had been signed off by a licensed engineer.When the accident Captain signs for the aircraft,he acknowledges reading the write up by the previous commander and the corrective action taken by the engineer.He must do this to accept the aircraft.
.

Not necessarily, it depends on the airline's rules for what exactly must be checked. For example, at mine, we have to look that all squawks are closed since the last airworthiness release. Some look back further than that, some don't. So if I see an airworthiness release from last night on a new (otherwise) blank page, I've satisfied my requirement without looking back to yesterday's squawk and corrective action.

[Dogma]

A worrying inability to handle an air data non-normal in a "new" jet

I'm personally concerned that the CAA UK has signed off UK operators doing a bit of CBT at home and thats the end of any differences training. Training in the UK has reached rock bottom in terms of quantity and in many training events quality

Sad state of affairs

[SLFinAZ]

We MUST assume that :
a)the accident crew were aware of the previous flights UAS because it was written up in the tech log and would prohibit that Commanders acceptance of the
aircraft unless it had been signed off by a licensed engineer.When the accident Captain signs for the aircraft,he acknowledges reading the write up by the previous commander and the corrective action taken by the engineer.He must do this to accept the aircraft.

We CAN REASONABLY assume that:
a)The accident crew would have given special attention to UAS during the pre-flight briefing.They would have reviewed memory items and/or a plan of action.
b)The accident crew would have tried to obtain first hand information from the previous crew if possible(phone)
c)The flying spanner was added to the accident crew because of the tech issue.Lionair is a big airline and will have engineers based at most destinations.
d)The accident crew would have discussed the absolute need NOT to take a known pitot static anomaly into the air,of the need to abort the takeoff if ASIs diasgree at 80 knots.
e)The fact that they did not abort the takeoff implies strongly that the UAS was undiscoverable on takeoff.Prime suspect static vent(s).

We CAN HOPEFULLY assume:
a)Both accident crew members had been trained in UAS events in the simulator on one or more occasions in their flying career.
b)that both crew members knew verbatim the UAS memory items and of the absolute need to disengage ALL AUTOMATION and recognize that there is a mismatch between reality and perception and fly the plane using common sense attitude/thrust combinations.
c)That the crew would have sufficient lateral thinking to disengage any system fed by ADIRU false data that might conflict with their ability to control the aircraft.eg STS.The pilots see/hear the trim wheel spinning.They know or should know it is fed via AP stab trim motor.They know where the AP stab trim cutout switch is.

We can NEVER assume:
a)that the startle effect in all non normal situations will be controlled and handled well by a crew.The longer the startle effect lasts the more chance for loss of muscle memory,cognitive thinking,and onset of panic.

So what do you think that the crews intent was once the UAS issue surfaced. Were they focused on returning to the field (level at 5k vs, gradual climb?) or did they intend to continue the flight as per the previous crew. Given the time lapse (roughly 5 minutes) at roughly 5000 feet without declaring an emergency I'd guess that the crew felt reasonably in control
of the situation. If they intended to continue why not maintain a gradual ascent like the previous flight? If in fact they had flight control issues (vs strictly UAS) why not declare an emergency? Is it possible that the engineer was in the jump seat and making trouble shooting recommendations or observations/requests? Would this create a distraction or complication that would lead to a sudden loss of control?

If the crew had never had a 3rd person involved in a sim setting is it a possibility that the unexpected distraction of that additional voice and potential trouble shooting interaction created enough confusion to lead to a sudden upset or undertake a course of action outside of the preflight brief? I'm wondering if the tech might have asked them to reengage the AP at some point for example?

[Aeroncabat]

From FR24 data, the aircraft was pretty much accelerating/overpowered throughout.

This is what intrigues me most. Overspeed is about the only consistent thing about the flight, at least from what can be ascertained so far from the "data".



If I was airborne and found out that I was now a test pilot, flying an aircraft that was not performing at all like it is supposed to, I would try to maintain the airspeed close to where I first found the problem, and then move cautiously toward the most forgiving portion of the flight envelope considering the current aircraft configuration.

Is it a stretch to imagine the airline in question "troubleshooting" an undetermined and assumed controllable anomaly in such a way?

Just my 2 cents from a steam gauge era viewpoint.

It is perhaps unfortunate in this instance that the crew did not have a few stone-age instruments onboard. (edit: at least instruments they paid any attention to) I often thank the almighty that the only things on my little crate that can even remotely be considered electronic are the lights and radios.

[henra]

We MUST assume that :
…
We CAN REASONABLY assume that:
...
We CAN HOPEFULLY assume:
…

I'm rather convinced that if all your assumptions had been fulfilled in this case we would not be having this Thread here.
And

We can NEVER assume:
a)that the startle effect in all non normal situations will be controlled and handled well by a crew.The longer the startle effect lasts the more chance for loss of muscle memory,cognitive thinking,and onset of panic

wouldn't have applied had they been sufficiently prepared mentally and training wise…

This is assuming it wasn't a totally unrecoverable problem with the airframe (which I would consider extremely remote).

[gums]

Salute!

Dat's right, Henra.
++++++++++++++++++++

Had to go back to the Alaska Airline crash with the " jackscrew nut. Wanted to see if there had been a squak on a preceding flight. Couldn't tell, but it would seem to me with all the damage that jackscrew had and the metal trapped in the big nut, that there would have been some slight indication to the PF. OTOH, with the use of the AP, the jammed stab was overcome by basic elevator trim. Finally, aero forces and commands by the PF caused the frst failure.
===================
Looking for a silver lining, this crash is a wakeup call to examine not only procedures but the design of the stab and pitch feel system, then all the air data inputs.

I tend to go with 'bird ( as in Machin') about possible PIO due to bad data coupled with a flaky pitch trim. You do not need a massive structural failure to reach extreme vertical pitch and speeds. We saw that at Rostov and that whole maneuver was done by the crew ( still have chills seeing the video). And one of our 73X drivers here claims that losing some or all of that trim/feel system can be challenging, especially at higher speeds.

And I have been a non volunteer test pilot on at least two flights, two types. Not fun. Only one required instant action and even that one I did the "don't just do something, sit there!" for first few seconds. Jet was still flying, so whatever I had was good enuf for then. picture on my Pprune profile bio.

Gums opines...

[porterhouse]

Nice idea but how does this computer know the pitch or AoA? ....
:rolleyes: :rolleyes:
How?? There are AoA sensors.

[henra]

Had to go back to the Alaska Airline crash with the " jackscrew nut. Wanted to see if there had been a squak on a preceding flight. Couldn't tell, but it would seem to me with all the damage that jackscrew had and the metal trapped in the big nut, that there would have been some slight indication to the PF. OTOH, with the use of the AP, the jammed stab was overcome by basic elevator trim. Finally, aero forces and commands by the PF caused the frst failure.

Salute gums!
That was indeed a really harrowing accident. And one which was completely unrecoverable by the crew. I can't imagine a similar mechanical problem in an only 6 months old (read: brand new) 737 MAX, though, despite the fact that the final dive reminds indeed somewhat of Alaska 261.


Looking for a silver lining, this crash is a wakeup call to examine not only procedures but the design of the stab and pitch feel system, then all the air data inputs.

I tend to go with 'bird ( as in Machin') about possible PIO due to bad data coupled with a flaky pitch trim. You do not need a massive structural failure to reach extreme vertical pitch and speeds. We saw that at Rostov and that whole maneuver was done by the crew ( still have chills seeing the video). And one of our 73X drivers here claims that losing some or all of that trim/feel system can be challenging, especially at higher speeds.

A mis- behaviour of the STS / Elevator feel system as a result of an Air Data problem ist indeed probably quite high up the probability scale as a main culprit for this one. That said there should have been ways of stopping the interference of STS, e.g. by pulling the AP stab trim CB.
Still it might be worth having a second look if the systems cannot be made to act more benignly. UAS in itself is probably a challenge to a Crew and topping this with automatic mis- trimming due to bad air data is obviously not a terribly good idea and has led to accidents in the past. That is one area of flight safety where there might be a little room for improvement from an engineering perspective (although how to do it exactly will have to be very cautiously thought through - it is easy to create unwanted side effects in other cases when not done properly).

Regards,
Henra

[DaveReidUK]

Had to go back to the Alaska Airline crash with the " jackscrew nut. Wanted to see if there had been a squak on a preceding flight. Couldn't tell, but it would seem to me with all the damage that jackscrew had and the metal trapped in the big nut, that there would have been some slight indication to the PF. OTOH, with the use of the AP, the jammed stab was overcome by basic elevator trim. Finally, aero forces and commands by the PF caused the frst failure.

The longitudinal trim control system had been working up to and including the initial phase of the accident flight.

[Squawk7700]

A mis- behaviour of the STS / Elevator feel system as a result of an Air Data problem ist indeed probably quite high up the probability scale as a main culprit for this one.

Perhaps don’t call it a mis-behavoir as it’s doing what it’s supposed to, based on the ASI inputs. Recognising and responding appropriately is the key.

Some of the first checklist items are to start switching things off.

You’d be behind the 8-ball the whole time if this failed and if you tried to turn around before you were stabilised.

Can the input source be switched on the STS? (I’m assuming it could be)

[Lord Farringdon]

You only have to look at that video of the wreckage, look at what is left of that engine (just the core), look at the shredded aircraft skin, read the reports that there seems to be no major piece of wreckage and of course that no victims remains are likely to be found intact, and you realise that this airplane from just few thousand feet hit the sea with such force that it was akin to flying into a mountain face or a building. Assuming MH370's final act was a similar nose dive into the ocean, but from a much higher altitude, is it any wonder nothing has been found? The engine cores of MH370 and some landing gear would fall to the bottom to be indistinguishable among rocks and detritus while the rest of the aircraft shredded into a million tiny pieces would slowly sift itself over hundreds of square miles of the Indian Ocean as these pieces drifted in the current and slowly descended the four miles to the bottom. Very much a case of "there's nothing to see here folks, go home".

But this Lion Air accident happened in only thirty metres of water. So I guess most of the remains will be concentrated but they may be buried in a similar way to the Value Jet crash that buried itself deep in a swamp. Like the Lion Air crash, the Value Jet aircraft ( loss of control due to fire in their case) was airborne for just 10 minutes before it rolled over and head down at 860km/h impacting with the swamp near vertically. The aircraft was destroyed on impact, with no large pieces of the fuselage remaining, and like Lion Air there were little in the way of intact human remains. I guess why I'm comparing these two is to understand just how difficult it may be to find or extract the CVR from the ocean bed. Although, the pinger going off is a really good sign that maybe the CVR is still above the sea bottom. The FDR presumably was and I assume that they are both co- located in the tail?

[Cool Guys]

Could we have a similar situation to Air Asia 8501; ie inflight fault finding gone awry, a CB pulled at an inappropriate time?

[olasek]

Assuming MH370's final act was a similar nose dive into the ocean, but from a much higher altitude, is it any wonder nothing has been found?
Bad assumption, large pieces of MH370 were found and in fairly good condition, whatever was found was not "shredded", so the current assumption is that MH370 hit water in a fairly benign fashion. Anyway, I would not mix both accidents, I would not draw any parallels, there is enough trolling in this thread already.

[PJ2]

Re pitot pressures and pitot covers etc., pitot pressures for the elevator feel computer are sourced from individual pitot tubes located on either side of the vertical fin, (and not the pitots supplying data to the ADRs).

The static ports for inputs to the elevator feel computer are located on the lower left rear of the fuselage, (below/fwd of the horizontal stab). This is for the -400 series and may differ for the Max.

This may distinquish a unique "UAS" problem, (single failure, referenced generally in the thread), from any possible combined UAS / STS / Elevator feel problem, (ref D.Bru comments). The SSDFR and CVR information become critical to understanding.

[Lord Farringdon]

Bad assumption, large pieces of MH370 were found and in fairly good condition so the current assumption is that MH370 hit water in a fairly benign fashion. Anyway, I would not mix both accidents, I would not draw any parallels, there is enough trolling in this thread already.
Alright forget I mentioned 'that other' accident. My comment was most certainly not an attempt to troll but to sincerely understand the conditions in which the search for the CVR is being undertaken. I could refer to another one that had some really good deep sea diver experience commenting on the thread (but won't in case I'm told off again) but if we don't learn something from these past recovery attempts what is the point of even having this thread? We become limited in what we can discuss with that sort of community censorship.

[phylosocopter]

It seems to me that the decision of the preceeding flight to continue to destination may have been quite properly made on safety grounds, they could have felt that they needed that transit time to become fully confident in controlling the craft in manual mode, they had an agreed flight plan and could plan ahead, It may well have taken them that length of flight to become confident that they could manover without entering PIO.

[Nomad2]

Trouble is these modern, highly automated and computerised jets are so simple to operate that most of the time a school kid can fly them.
But when the computers and automation get glitchy, they suddenly need a pilot, and a good one at that.
It seems that most of the time, that pilot is right there, and ready- but when he isn't, we get AF447 or any of the recent 'loss of control' type accidents.
Maybe the memory action for some of these system failures should be 'Automatics off. FLY. Do nothing for a while. Think'.

[Capn Bloggs]

Maybe the memory action for some of these system failures should be 'Automatics off. FLY. Do nothing for a while. Think'.
It is. That is exactly the Memory procedure for a UA situation. and set X° pitch and Y° N1 (depends on the aircraft type). Pretty simple really.

[VGCM66]

Everybody forgot to: Aviate, Navigate, Communicate in that flight. So those same somebodies it seems ultimately ended up stalling the plane into the Ocean. Securing the flight by any means was priority number one, first and only. Once safe, they could have troubleshooted the problem then.

Cheers,

[A Squared]

Everybody forgot to: Aviate, Navigate, Communicate in that flight. So those same somebodies it seems ultimately ended up stalling the plane into the Ocean. Securing the flight by any means was priority number one, first and only. Once safe, they could have troubleshooted the problem then.

Cheers,

No, it doesn't seem that they stalled the plane into the ocean at all. Virtually all evidence revealed to date is consistent with a high speed dive into the ocean. Whatever happened, stalling the airplane is one of the less likely scenarios.

[Volume]

but hey, we've stalled it Bloggs, get the nose down!!
Unfortunately this is not what generations of airline pilots were trained for. Lots of training books and examination requirements were focusing on recovering stall by applying engine power and prioritizing to maintaining altitude.

Which has a valid element, "get the nose down!!" may easily get you into a very unusual attitude you typically never fly in, outside the envelope of your systems (elevator feel, speed trim...) which may just trigger the next unusual reaction of the aircraft.
You may end up in a steep dive out of control if you push it too hard in an attempt to "get the nose down!!", which may have been exactly what happened in this case.
Before you start any agressive maneuvre out of the usual envelope of a large transport aircraft, you should be very sure you are not following a false warning, which can be the result of UAS, like the overspeed warning the birgenair pilots were facing.

There should be no control inputs with two exclamation marks when flying a large transport...

[bsieker]

Everybody forgot to: Aviate, Navigate, Communicate in that flight. So those same somebodies it seems ultimately ended up stalling the plane into the Ocean. Securing the flight by any means was priority number one, first and only. Once safe, they could have troubleshooted the problem then.

Cheers,

And what is the purpose of this post? We don't even know what happened, and yet you already assert that the flight crew screwed up. Oh, if only we could find enough pilots who never make any mistake, then everything would be perfectly safe.

But even suppose we find that someone did something which we now know contributed to the accident, here's something to keep in mind:

It is never enough to find out who made which mistake. It is more useful to ask why the people at the sharp end did what they did. Almost always we find that what the pilots (or other operators) did, made sense to them at the time. With perfect hindsight, and all the time in the world to analyse, we sometimes find that it was not the best thing they could have done. But it is useful to try to understand their limited view of things and limited time and mental processing capacity available, to figure out what they might have thought, and how they might have reasoned. Don't start with the assumption that because they made a "mistake", that these pilots were particularly bad at their job. Others might make the same, or similar mistakes, faced with the same situation and the same set of incomplete, and perhaps seemingly contradictory, information available.

Only then can we start and try to find ways to prevent it in the future.

As Sidney Dekker put it in "The Field Guide to Understanding 'Human Error' "(paraphrasing): mistakes should not be seen as the cause of the accident, but as a symptom of larger problems.

Cheers,
Bernd

[silverstrata]

Trouble is these modern, highly automated and computerised jets are so simple to operate that most of the time a school kid can fly them. But when the computers and automation get glitchy, they suddenly need a pilot, and a good one at that'.


Except that the B737 has no computers. The flight control system and STS system is good old 1961 engineering - whacking great 5mm steel cables to all control surfaces, plus a bit of hydraulic servo. And while it can be a bit heavy if all the hydraulics fail, it basically becomes a large Cessna 172. And there are no ‘computers’ to fail.

Even the STS system can hardly be called a computer, as it only has 200 bytes of iron-ferrel core memory. And the comment that the STS was reverse trimming and not assisting, is a bit of a red herring, as it always does that. Most annoying system ever, because pilots like aircraft to be in trim, not out of trim. And the STS can be overcome with trim input, as pilots do every day when hand flying, or by disconnecting the trim system. (Whatever the STS does, you just oppose it, otherwise the control forces are absurd).

And upon trim system disconnection you are left with that enormous clanking manual stab-trim-wheel, with more thick steel cables, that was originally installed as a steam-valve on the Titanic - but it sure saved money on design costs....

Silver

[Clandestino]

To those of you admonishing your colleagues for tossing around first-impressions while “bodies are still warm,” THAT’S WHAT WE DO! WE’RE PILOTS! This thread is not a news organization, it’s a crowded pub. It’s OK to put your bets on the table about what happened before the investigation has even begun, much less ended.


Hear, hear! Of course it is OK, especially if one's opinion is based on misunderstanding of the aeronautical fact one has heard in some pilot pub, left to ripen in a vat of runaway imagination. A pinch of desire to get attention by fearmongering also helps. Some contributions to the discussion are qualitywise getting close to the heights attained by Chapman, Palin, Cleese et al in 1970s.

Just in case you are really here for information and not, like dirty old me, for entertainment:

Maybe there were aeroplanes of Vought F7U generation that could be stalled at any speed, but to achieve that one needs sturdy airframe that can reach stall before structural limit, powerful elevator that can generate high alpha at high speed and low stick force gradient so the pilot can pull the Gs, all of which transport aeroplanes are lacking. Forget about high speed (high speed as in "significantly higher than 1G") stalls in airliners.

Children of the Magenta is one of the most abused video in the history of the PPRuNe. It's point is not that today's pilots don't know how to fly, it is that over-reliance on the systems we don't really understand can happen to anyone and that pilots should always be ready to go into downgraded GTFOH mode.

Changing of control feel or efficiency is not an issue in itself on any airliner, happens rather frequently and extremely often ends up in successful landing.

STSon NG is nowhere near FBW Airbus autotrim by its speed & authority and it's only half-useful (methinks I'm overcrediting it here anyway). Quick blip on trim switch will stop it doing whatever it thinks is appropriate for the situation. I have no idea if some of its arcane faults can really introduce pitch trim runaway but then it doesn't mater: if it does, memory (or recall if that is your parlance) items for runaway stabilizer include activating both stab trim cutout switches. If it doesn't help, grab and hold the trim wheel. Haven't done MAX conversion yet but I really doubt the mighty MAX is anything but grafting of some new fancy displays and engines on old, tired, 1960ies basic airframe.

Not everything is automated today (taxiing isn't for sure) and even automation fails regularly so why do we have to wait for quite a lot between the crashes so the resident PPRuNe experten get the excuse to air their "we got it wrong and we have to return to the straight aeronautical path" pet theories, despite the humongous growth of air traffic? Well, it's not just about the modern systems being far more reliable than those of steam gauge era. Pilot of yesterday who knew how to fly, unlike the flying youth of today, is mythical creature. Quite a lot of them lost: control or idea where they are or how much fuel they still have and quite a few time we didn't even bother to figure out what happened or when we did, we would just say it was pilot's error while letting the airline that had failed to provide relevant and meaningful training of the hook. Accident rates of today's Indonesia or Africa would put those of USA in 1950ies to shame. Modern pilots (even the dreaded MPLs) are well trained and cope successfully with instrument/system/automation failures on daily basis (collectively, that is), flying manually just fine. Most of the incidents don't make it even as far as AvHerald and remain buried in company safety bulletins. Those ending in tragedy tend to be outlying ones where pilots do something so contrary to their basic training that currently we have no psychological tool to explain what the heck they were thinking. Now faced with the things we found dangerous and explicable, and fearing them for a few quite good reasons, we come up with pretty interesting and somewhat flawed solutions. The authorities promulgate the truth that aeroplane can be stalled at any attitude, which is not whole truth as the aeroplanes that recently ended in "any attitude stall" did so with quite active help from their crews in achieving and maintaining stall. Some of the concerned PPRuNers are suggesting more technology, such as AoA indicators, as if the pilot unable to keep the proper attitude will somehow magically be snapped out of his detachment from reality by yet another gauge. While I'm hoping that someone, somewhere will come with the plausible explanation of recent LoC accidents, I'm not holding my breath.

[A Squared]

Except that the B737 has no computers. The flight control system and STS system is good old 1961 engineering - whacking great 5mm steel cables to all control surfaces, plus a bit of hydraulic servo. And while it can be a bit heavy if all the hydraulics fail, it basically becomes a large Cessna 172. And there are no ‘computers’ to fail.

Even the STS system can hardly be called a computer, as it only has 200 bytes of iron-ferrel core memory. And the comment that the STS was reverse trimming and not assisting, is a bit of a red herring, as it always does that. Most annoying system ever, because pilots like aircraft to be in trim, not out of trim. And the STS can be overcome with trim input, as pilots do every day when hand flying, or by disconnecting the trim system. (Whatever the STS does, you just oppose it, otherwise the control forces are absurd).

And upon trim system disconnection you are left with that enormous clanking manual stab-trim-wheel, with more thick steel cables, that was originally installed as a steam-valve on the Titanic - but it sure saved money on design costs....

Silver



https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/300x358/aw_geez_not_this_crap_again_1a9cc6d86e7e6d1c54b7b51ec948ed1b 252eec2e.jpg


Sigh, first you were claiming that it wasn't a computer because it only had a 286 microprocessor (Which is a bizarre claim to those of us old enough to recall when all the cool kids had 286 processors in their computers) Now you pop back up claiming it's not a computer because it only has a certain amount of memory ... seriously? Do you even hear the things you're saying? Might I suggest that whatever larger point you might be trying to make is obscured by your misguided and factually incorrect semantics? Whatever this device is, it has a digital CPU, it has digital memory, it takes digital input data and performs logical programming steps to generate digital output data. Most of the rest of the world calls that a computer. If it's really important to you for it not to be called a computer, can you suggest a word or combination of words that you would find acceptable? I don't see that anyone has claimed that the 737 is fly-by-wire a la the Airbus, but it is certainly equipped with a device that most of the rest of the world calls a computer, whcih is autonomously making adjustments to large control surfaces whcih affects how and where the airplane flies.

[c_coder]

200 bytes of iron-ferrel core memory.
Core memory, really? There are some very good low powered microcontroller platforms around. Some may be comparable in performance to an 80286, They show up on space probes, where resistance to radiation is important. But nobody is using core memory, other that on a few antiques.

[Brian W May]

Good post Capn Bloggs. Trouble is us pilots spent so many years dumbing down our profession that everyone thinks they can do it. This includes the owners & management hence recruit anyone especially those with money. The schools being commercial operations are very loath to fail those candidates without flying ability as they would loose students. Unfortunately not every one has the aptitude to be a pilot, in the true sense of the word even those that think they do. Quote “Fly the d** Arroplane & don’t over stress it. Get your cockpit management in place (CRM) & get the other guy to diagnose. If you want to confirm what he thinks hand him control & cross check his thoughts. It will be taking 80 to 90 % of your cognitive ability to control an “erroneont” aeroplane.

I think you need your medication adjusted old chap . . . I think I know what you mean but some of it really is in the delivery.

[Switchbait]

I know that sometimes the simulator does not entirely accurately reflect the way that the aircraft behaves, however at no stage during the many Airspeed Unreliable events I have flown in the simulator, did the Speed Trim System do anything at all that I can remember, and it most certainly did not behave in such a way that presented any problem.

I cant help but think this constant reference to the STS in this thread is due lack of understanding of the STS.

I dont know what caused the airplane in question to end up in the sea, but I highly doubt that the STS caused it.....

The data recorder has been recovered. Give them a few days and some FACTUAL information will be available.

[A Squared]

I know that sometimes the simulator does not entirely accurately reflect the way that the aircraft behaves, however at no stage during the many Airspeed Unreliable events I have flown in the simulator, did the Speed Trim System do anything at all that I can remember, and it most certainly did not behave in such a way that presented any problem.

I cant help but think this constant reference to the STS in this thread is due lack of understanding of the STS.

I dont know what caused the airplane in question to end up in the sea, but I highly doubt that the STS caused it.....

The data recorder has been recovered. Give them a few days and some FACTUAL information will be available.


I'll cheerfully admit that my entire understanding of the 737 STS comes from this thread, or reading I've done as a result of this thread, so there may be some pretty big gaps in my knowledge. That said, the idea this can't be the cause because it doesn't act that way in the simulator bears comment. Simulators only do what they have been programmed to do. that means that they only simulate failures whcih have been anticipated and programmed into the software. It is certainly within the realm of possibility for a system to fail in a manner that hasn't been anticipated by it's designers, and produce unanticipated results that wouldn't have been programmed into a flight simulator.

[dmba]

So having airspeed issue doesn't necessarily result in the aircraft falling out of the sky, as proven on the previous flights. What's different this time?

[Seabreeze]

FDR Pingers transmit at 37.5 kHz while most pilots can't hear much beyond 16 KHz (maybe 20 if you are young).

In an earlier life I had some experience finding underwater equipment which was "marked" by a pinger. Pinger receivers usually relay the signal at a frequency that the user (pinger receiver operator) can hear, and some receivers are directional allowing an operator to "home" in on the signal by moving in the direction from which the signal appears to be coming. Having said this, this is not a very accurate way of finding a pinger, and even in shallow water ( 30 m) it is difficult to get much closer than 100-150m from a pinger. Hence the need for divers.

They use 37.5 kHz since there is not so much background sea noise at that frequency.

Seabreeze

[Station Zero]

If anyone wants to know a little more about ELBs fitted to recorders, do a search for Dukane DK100 or DK120 or Teledyne Benthos ELP-362D. Plenty of info on them and their theory of operation.

[SLFinAZ]

So having airspeed issue doesn't necessarily result in the aircraft falling out of the sky, as proven on the previous flights. What's different this time?

The presence of an engineer for certain.

[JulioLS]

So what do you think that the crews intent was once the UAS issue surfaced. Were they focused on returning to the field (level at 5k vs, gradual climb?) or did they intend to continue the flight as per the previous crew. Given the time lapse (roughly 5 minutes) at roughly 5000 feet without declaring an emergency I'd guess that the crew felt reasonably in control
of the situation. If they intended to continue why not maintain a gradual ascent like the previous flight? If in fact they had flight control issues (vs strictly UAS) why not declare an emergency? Is it possible that the engineer was in the jump seat and making trouble shooting recommendations or observations/requests? Would this create a distraction or complication that would lead to a sudden loss of control?

If the crew had never had a 3rd person involved in a sim setting is it a possibility that the unexpected distraction of that additional voice and potential trouble shooting interaction created enough confusion to lead to a sudden upset or undertake a course of action outside of the preflight brief? I'm wondering if the tech might have asked them to reengage the AP at some point for example?The data from flight radar (with all the normal caveats) suggests that they never had control of the aircraft.... But your point about the added distraction of an engineer is well made.

[Derfred]

I know that sometimes the simulator does not entirely accurately reflect the way that the aircraft behaves, however at no stage during the many Airspeed Unreliable events I have flown in the simulator, did the Speed Trim System do anything at all that I can remember, and it most certainly did not behave in such a way that presented any problem.

I cant help but think this constant reference to the STS in this thread is due lack of understanding of the STS.

I dont know what caused the airplane in question to end up in the sea, but I highly doubt that the STS caused it.....

The data recorder has been recovered. Give them a few days and some FACTUAL information will be available.

Thank you, Switchbait. I have tried to suggest the same, but you have done it eloquently.

[Less Hair]

Except that the B737 has no computers. The flight control system and STS system is good old 1961 engineering...

The MAX even has some fly by wire (spoilers) on top.

[gums]

Salute!

I would not be too quick to eliminate a simple problem with the STS or feel system that made another "simple" problem worse( if UAS is a "simple" problem), resulting in loss of control. In other words, a simple reversed wire could have reduced or even reversed back pressure. So pull back and the sucker moves faster/further than you are used to. I speak from personal experience with a reversed wire on my aileron-rudder-interconnect. The jet was very benign WRT rudder requirements unless you crammed in a gob of aileron quickly. So shortly after takeoff I did my normal "sharp" roll to course and whoa! Nose slices the opposite way big time. Scary and neutral stick and no more trouble shooting. My GIB also noticed what happened and we agreed to cautiously come bak and write it up. Sure enuf, the connectors were not polarized and a tech had inserted them the wrong way. So new item on personal checklist when doing the control movement check I would ask ground crew if rudder was moving slightly in direction of roll command.

Even the Boeing description claims that the trim/feel system increases static stability, and the tendency to get back to "trimmed" AoA/speed. So imagine that working backwards!?!

Secondly, you don't need to have a high speed stall to wind up in a high speed dive. You can get there with a slow speed stall and then an unrecoverable dive, although availabkle data does not show any real slow speeds on this plane. The 737 rudder hardovers way back then resulted in steep, high speed dives.

The data should be able to show what happened, and the CVR would be as helpful as it was in AF447.

Gums opines...

[Rananim]

I know that sometimes the simulator does not entirely accurately reflect the way that the aircraft behaves, however at no stage during the many Airspeed Unreliable events I have flown in the simulator, did the Speed Trim System do anything at all that I can remember, and it most certainly did not behave in such a way that presented any problem.
I concur but.....
We're going round in circles here,data is minimal,no engineering input.
It doesnt have to be STS,it could be AP STAB trim.Whats important is that something gave them unwanted trim based on faulty ADIRU data.Now that something can be STS or AP STAB trim.Thats assuming unwanted "incorrect"(ie incorrect for the reality they were facing) trim is the golden nugget here.Talk of elevator feel providing the incorrect sensitivity for the high speed has been sparse here.I prefer the trim theory as it would explain the sudden loss of control more readily IMO.We can only work on deduction here so lets try that.
Previous flight commander reports ALT IAS disagree and STS trimming "wrong way"------->we deduce UAS undiscoverable on takeoff---->we deduce he was PF and he flew manually during UAS event (STS was operating) before disabling AP stab trim and giving control to FO------->Flight returns to Jakarta below RVSM airspace with FO flying manually.
Accident flight....Commander reads and signs tech log----->we deduce he knows of the previous UAS event----->we deduce further he will surely be stop minded if ASI disagree on takeoff----->takeoff is not aborted------>therefore same fault occurs on accident flight as previous flight------>possible static vent problem------->not discoverable until after liftoff------>Capts ALT lags or sticks------>Capts ASI underreads in climb.
We know from previous UAS accidents crews want to throw it back to the autopilot.Understandable but highly undesirable.What if the accident Captain engages AP B(good side) after takeoff in an effort to give himself time to think?What will happen?AP B will use FCC B to control pitch roll up to MCP selected altitude of 5000 right?FCC B is being fed with right side ADIRU data which we are assuming is good.Things dont go well and control is lost....why?AP stab trim is being controlled by FCC A(bad side data).FCC A commands stab trim/STS signal on power up.Result------->overspeed with AP stab trimming nose down.The crew are confused and disoriented(by low AS on Capts side)and distracting warnings, and dont retard thrust,possibly dont retract flaps.They ask ATC for speed readout and return to Jakarta.AP captures 5000 with difficulty and pitch oscillations,soon after sudden loss of control.

[AI23B]

All of these discussions, suppositions theories and explanations are of no relevance in a country where saving face and money is more important than human life. The aeroplane was logged as having a similar IAS fault more than once and yet was signed off as being serviceable each time. It should have been removed from service and manufacturers input sought after the second incident and it's about as simple as that - hindsight? - no common bloody sense.

[GarageYears]

Because it has a lot further range than audible frequencies, and detectors are readily available.

Next...

Actually, no, the latest research indicates that an 8.8kHz pinger has much greater underwater range...

"Following the two simulation exercises practiced in this study, it is quite clear that the decision made by the aeronautical administrators to adopt the use of a low-frequency ULB in the fuselage of airplanes was justified. Despite the differences between the two methods, both agree on higher pressure values at longer distances for the 8.8 kHz pings, as expected. The numerical model indicates the possibility of detection (RL > 10 dB [12]) at distances of ~8 km for the 8.8 kHz signal, while for the 37.5 kHz signal the detection can be considered not possible since the water depth (3790m) was bigger then the range where RL = 10 dB."

See: https://www.researchgate.net/publication/318719682_Underwater_Locator_Beacon_signal_propagation_on_tr opical_waters

Note: The ULBs fitted in Air France Flight 447 (https://en.wikipedia.org/wiki/Air_France_Flight_447), which crashed on 1 June 2009, were certified to transmit at 37.5 kHz for a minimum of 30 days at a temperature of 4°C. Investigating the crash, the BEA recommended that FDR ULBs' transmission period be increased to 90 days and for "airplanes performing public transport flights over maritime areas to be equipped with an additional ULB capable of transmitting on a frequency (for example between 8.5 kHz and 9.5 kHz) and for a duration adapted to the pre-localisation of wreckage" (i.e. with increased range).

- GY

[Smott999]

I concur but.....
We're going round in circles here,data is minimal,no engineering input.
It doesnt have to be STS,it could be AP STAB trim.Whats important is that something gave them unwanted trim based on faulty ADIRU data.Now that something can be STS or AP STAB trim.Thats assuming unwanted "incorrect"(ie incorrect for the reality they were facing) trim is the golden nugget here.Talk of elevator feel providing the incorrect sensitivity for the high speed has been sparse here.I prefer the trim theory as it would explain the sudden loss of control more readily IMO.We can only work on deduction here so lets try that.
Previous flight commander reports ALT IAS disagree and STS trimming "wrong way"------->we deduce UAS undiscoverable on takeoff---->we deduce he was PF and he flew manually during UAS event (STS was operating) before disabling AP stab trim and giving control to FO------->Flight returns to Jakarta below RVSM airspace with FO flying manually.
Accident flight....Commander reads and signs tech log----->we deduce he knows of the previous UAS event----->we deduce further he will surely be stop minded if ASI disagree on takeoff----->takeoff is not aborted------>therefore same fault occurs on accident flight as previous flight------>possible static vent problem------->not discoverable until after liftoff------>Capts ALT lags or sticks------>Capts ASI underreads in climb.
We know from previous UAS accidents crews want to throw it back to the autopilot.Understandable but highly undesirable.What if the accident Captain engages AP B(good side) after takeoff in an effort to give himself time to think?What will happen?AP B will use FCC B to control pitch roll up to MCP selected altitude of 5000 right?FCC B is being fed with right side ADIRU data which we are assuming is good.Things dont go well and control is lost....why?AP stab trim is being controlled by FCC A(bad side data).FCC A commands stab trim/STS signal on power up.Result------->overspeed with AP stab trimming nose down.The crew are confused and disoriented(by low AS on Capts side)and distracting warnings, and dont retard thrust,possibly dont retract flaps.They ask ATC for speed readout and return to Jakarta.AP captures 5000 with difficulty and pitch oscillations,soon after sudden loss of control.

....you theorize Captain realizes poss faulty AS on his side, and engages AP B (good side AS) ...yet AP Stab Trim is still being controlled by the (bad side) FCC A.
What should Captain have done to get Stab Trim looking at B?

As a mere SLF freight it seems odd that Cap would recognize faulty airspeed on his A side, and take action to flip the AP to B side....yet still allow the AP Stab Trim (which I infer is separate somehow) to continue to receive input from the faulty A side...?

Perhaps this is a common mistake? All thoughts appreciated and thanks again for the informative forum.

[bobdxb]

Indonesia's National Transportation Safety Committee (KNKT) said on Monday (Nov 5) that the Lion Air jetliner that plunged into the Java Sea last Monday suffered a more devastating crash impact than an AirAsia flight that crashed into the sea in December 2014.

The size of the debris collected so far showed the ill-fated Lion Air dived into the water at high speed and the plane broke in pieces upon impact with the water body, Mr Soerjanto Tjahjono, chief of the National Transportation Safety Committee, told a radio station.

"The plane broke apart upon impact when it hit the water. There has been no signs of material fatigue. There were worries by some that the plane broke apart in mid-air due to material fatigue. We can confirm it is not the case," he told Elshinta radio.

[bobdxb]

Sources say that the Indonesian aviation authority's inspectors have already found "faults" in 3 other Lion Air 737s... things like "sensors not sensing" and display errors like the ones squawked before for the accident airplane. Does not look good for the airline, and puts "contributing factors" very much in play.

In order to dispel rumors, "we want to clarify that in the black box there were four flights that experienced problems with the airspeed indicator," agency head Soerjanto Tjahjono said.

[GarageYears]

....you theorize Captain realizes poss faulty AS on his side, and engages AP B (good side AS) ...yet AP Stab Trim is still being controlled by the (bad side) FCC A.
What should Captain have done to get Stab Trim looking at B?

As a mere SLF freight it seems odd that Cap would recognize faulty airspeed on his A side, and take action to flip the AP to B side....yet still allow the AP Stab Trim (which I infer is separate somehow) to continue to receive input from the faulty A side...?

Perhaps this is a common mistake? All thoughts appreciated and thanks again for the informative forum.


If you're referring to the Speed Trim System (STS) it has it's own speed sensing system based on pitots located at the rear of the aircraft.

-GY

[Rananim]

Where has it been verified that the STS was trimming the wrong way, (meaning 'reversed operation', counter to pilot intention)
It wasnt...it was trimming as designed...but to the pilot it appeared to be trimming the wrong way..... makes sense as he had corrupted CAS data.

What should Captain have done to get Stab Trim looking at B?
He cant as far as I know.FCC A commands the signal from power up.After landing,the squat switch on the gear will change it to FCC B for the next flight.The pilot must disengage AP stab trim to stop the unwanted trim.Using electrical trim overrides it but wont disable it.After 5 seconds,STS will trim again.Pulling on the stick will stop the trim but again it will start trimming if stick pressure is released.It has to be disabled in a UAS(or rather this particular UAS scenario).Ive never encountered this problem during UAS in simulator.However,this doesnt mean it cant happen.Too many variables.....ie type of UAS,which FCC is controlling etc.

[Smott999]

If you're referring to the Speed Trim System (STS) it has it's own speed sensing system based on pitots located at the rear of the aircraft.

-GY

I understand that STS has its own separate AS inputs.

however Ran indicated that AP has Stab Trim input as well, and theorized the Cap May have left AP Stab Trim on the faulty side A.
Merely SLF here and perhaps Ran was in error. Ran weigh in as you will thanks all.

[Lifer01]

Specifically, the Speed Trim function does not operate with Autopilot engaged. It’s essentially a “low speed” function.

The AP can, of course, trim the stab though.

[Smott999]

It wasnt...it was trimming as designed...but to the pilot it appeared to be trimming the wrong way..... makes sense as he had corrupted CAS data.


He cant as far as I know.FCC A commands the signal from power up.After landing,the squat switch on the gear will change it to FCC B for the next flight.The pilot must disengage AP stab trim to stop the unwanted trim.Using electrical trim overrides it but wont disable it.After 5 seconds,STS will trim again.Pulling on the stick will stop the trim but again it will start trimming if stick pressure is released.It has to be disabled in a UAS(or rather this particular UAS scenario).Ive never encountered this problem during UAS in simulator.However,this doesnt mean it cant happen.Too many variables.....ie type of UAS,which FCC is controlling etc.

...again, as a SLF it seems a bit odd that there exists the opp to switch AP to B, whilst AP Stab Trim is fixated on A and at best can be disabled. Why not allow AP Stab Trim to use B? I’m sure there’s a good reason! But your theory is quite scary....AP Stab Trim just continues to push down given it’s on faulty too-slow A-side airspeed...?

[MurphyWasRight]

If the crew had never had a 3rd person involved in a sim setting is it a possibility that the unexpected distraction of that additional voice and potential trouble shooting interaction created enough confusion to lead to a sudden upset or undertake a course of action outside of the preflight brief? I'm wondering if the tech might have asked them to reengage the AP at some point for example?

The data from flight radar (with all the normal caveats) suggests that they never had control of the aircraft.... But your point about the added distraction of an engineer is well made.


Could someone who knows the regulation and actual practice comment on the allowed role of a flying spanner?
Seems sensible to me that on a revenue flight they should have no input unless an emergency is recognized in which case one of course one would use whatever resources seems appropriate.

Attempting to debug a possible intermittent problem while carrying passengers should be way outside the permitted realm.

I am not a pilot but have plenty of experience with 'group debugging' which is almost always less efficient than a single concentrating person, perhaps with some 'spare hands' turning knobs or holding probes but otherwise staying out of the thought process.

[Rananim]

Originally Posted by GarageYears https://www.pprune.org/images/buttons/viewpost.gif (https://www.pprune.org/rumours-news/614857-indonesian-aircraft-missing-off-jakarta-32.html#post10302459)If you're referring to the Speed Trim System (STS) it has it's own speed sensing system based on pitots located at the rear of the aircraft.


Hmm.........no.We really need engineering input to try and get somewhere here but........ FCCs command the STS, AP STAB TRIM functions.
The air data inertial reference unit (ADIRU) sends these signals
to the FCC for speed trim calculations:
* Computed airspeed (CAS)
* Mach
* Inertial vertical speed
* Roll angle
* Angle of attack.
AMM 22


Each ADIRU sends these air data reference (ADR) signals to its
onside FCC:
* Uncorrected altitude
* Baro corrected altitude number 1
* Baro corrected altitude number 2
* Mach
* Computed airspeed
* Maximum allowable airspeed (VMO/MMO)
* True airspeed
* Static pressure
* Total pressure
* Indicated angle of attack.
AMM 22
From above L ADIRU sends CAS to FCC A. FCC A commands the STS signal via AP stab trim motor,just like when it commands AP stab trim

Inputs to ADIRU?
The pitot static system is comprised of three separate pitot tubes and six flush static ports.Two pitot probes and four static ports interface with the air data modules.The remaining auxiliary pitot probe and alternate static ports provide pitot and static pressure to the standby instruments.The air data modules convert pneumatic pressure to electrical signals and send these data to the ADIRUs.Each pitot air data module is connected to its on-side pitot probe;there is no cross-connection.The air data module connected to the Captain's pitot probe sends information to the left ADIRU,while the air data module connected to the First Officer's pitot probe sends information to the right ADIRU.
FCOM 10.20.13
Elevator pitots have no interface with ADIRUs.They feed the elevator feel computer.

FCC A and FCC B
The FCC can supply these commands:
* A/P trim nose up
* A/P trim nose down
* Speed trim nose up
* Speed trim nose down.
If the autopilot is engaged, the FCC can supply an A/P trim
command. If the autopilot is not engaged, the FCC can supply a
speed trim command.
AMM 22

Column Switching Module
When the main electric trim is in operation, switches in the
column switching module open. This does not let the FCC clutch
signal go to the trim actuator. The FCC and the main electric
trim cannot control the trim actuator at the same time.
If the pilot moves the control column forward or aft, signals go to
the two FCCs. These signals do not allow the FCC to supply trim
commands that do not agree with the pilot.
AMM 22
Speed Trim Stability
The speed trim controls the stabilizer to oppose any change of
airspeed. An increase in CAS causes a nose up trim command
to the stabilizer. A decrease in CAS causes a nose down trim
command to the stabilizer.
AMM 22

STS is not there for fun.Its needed for certification.By retrimming it gives you more elevator authority,particularly important in high AoA low CAS
conditions.Nothing absurd about it.

[Kiwiconehead]

Could someone who knows the regulation and actual practice comment on the allowed role of a flying spanner?
Seems sensible to me that on a revenue flight they should have no input unless an emergency is recognized in which case one of course one would use whatever resources seems appropriate.

Attempting to debug a possible intermittent problem while carrying passengers should be way outside the permitted realm.
I've done both "flying spanner" - which is paxing on the flight so as to have engineering coverage at an outstation, and being an observer for intermittant faults which is really not helpful in most cases anyway.

Flying spanner I have usually sat in the cabin, although on short flights on one contract sat in the jumpseat as the passengers on that contract asked me too many stupid questions when I was in the cabin.

I have done observation flights for things like yaw dampers dropping out on takeoff rolls and the like, but you can't tell much other than "yes the yaw damper dropped out" CDS fault summaries and QAR provide much more data from which you can analyse faults, if you have technical support (thats what the likes of Boeing are for).

I have been asked advice on what to do with failures when in the jumpseat, and my advice is always "whatever the QRH says" then after that is actioned I have discussed the system with crew. But not for troubleshooting, more for crew information.

[MurphyWasRight]

Thanks KiwiC.
I have been asked advice on what to do with failures when in the jumpseat, and my advice is always "whatever the QRH says" then after that is actioned I have discussed the system with crew. But not for troubleshooting, more for crew information
That is what I would hope/expect to be the case.

BTW: When I mentioned not debugging on a revenue flight I meant taking action, not observing and possibly correlating data not recorded such as actual displays etc although as you point out in most cases it probably just confirms the reported fault.
I suspect there may be times when observing the fault first hand may clarify things since the write up could be ambiguous,vague or operates as designed but not as desired/expected.

[gulliBell]

Please excuse my ignorance with the question, but is it possible to fly a complex commercial jet airliner like this when the flight instruments go whacky by pretending it's a Cessna 172, set the power manually, fly an attitude manually, trim it manually, and look outside? Or is that too difficult for pilots of push button planes now?

And in this instance where an air data computer (or whatever gizmo) was replaced as a fix for a defect entered into the technical log, is a maintenance assessment flight required to actually check that the fault has been fixed?

[DaveReidUK]

And in this instance where an air data computer (or whatever gizmo) was replaced as a fix for a defect entered into the technical log, is a maintenance assessment flight required to actually check that the fault has been fixed?

Nothing was replaced following the previous DPS-CGK flight (for which we have seen the tech log).

As I posted on the day after the crash:

Somebody please correct me if I'm wrong (I belong to the avionics = PFM school), but the rectification action carried out for that entry in the tech log appears to have been to clean the connector plug on the elevator feel computer followed by a ground test, which was successful.

I'd have thought that (a) the EFC might well have been performing correctly anyway (in flight), given that the warning light responds to differences in either hydraulic pressure or pitot dynamic pressure, which were presumably detected by the EFC and (b) a ground test wouldn't necessarily be able to reproduce either of those conditions.

I'd be interested to know what procedure the AMM prescribes for diagnosing and rectifying this issue.

I haven't seen any subsequent posts re what the AMM says.

[TURIN]

As previously posted, I find it hard to believe that a type that has been in service with the operator for nearly a year and a half, flying on a route that gets 6 daily rotations with the type, needed to carry a flying spanner just to sign off the aircraft at the outstation.

I am frequently called out to assist one particuler airline that has been operating a modern type for nearly two years and they still carry a flying spanner to certify the log. Some airlines just don't like other people messing with their kit and also like to 'control' the certifier. (read into that what you will).

[JLWSanDiego]

Great discussion but wondering if a "TechLog" forum should be started for much of the "what ifs" and "how does it work" as was done on AF447 ?

[SLFinAZ]

Please excuse my ignorance with the question, but is it possible to fly a complex commercial jet airliner like this when the flight instruments go whacky by pretending it's a Cessna 172, set the power manually, fly an attitude manually, trim it manually, and look outside? Or is that too difficult for pilots of push button planes now?

And in this instance where an air data computer (or whatever gizmo) was replaced as a fix for a defect entered into the technical log, is a maintenance assessment flight required to actually check that the fault has been fixed?

Basically if you look at the previous posts specific to both memory items and the QRH that's more or less what your describing, you start by turning off the various levels of automation and then setting pitch and power. So the real question is what exactly was going on? Was there a compounding technical issue or possibly a slow response that caused a structural failure (overspeed with flaps still down for example) or did the crew get distracted for some reason or fail to follow the recommended procedures? The simple truth is that by itself the UAS should not have been enough to cause a loss of control without some other variables at work. This did not happen at cruise to an unsuspecting crew but was a known issue with an engineer onboard and was in fact an expected event if in fact the 4 previous flights all had issues. The limited factual information makes it somewhat baffling till we get the CVR transcript...

[FanControl]

is a maintenance assessment flight required to actually check that the fault has been fixed?

Exactly but it seems they did not even diagnose the problem correctly, with this cannon plug stuff.

[rmac2]

So just to clarify regarding the last few posts

The STS reads from alternate FCC on alternate flights. Reset by the landing gear squat switch.

So on the previous flight which retained controlability during an entire night flight from Bali to Jakarta despite UAS on Captain side was followed by a flight which lost control in day VMC during a period of UAS on Captain side.

Hmmm, food for thought

[Capn Bloggs]

https://www.abc.net.au/news/2018-11-05/lion-air-jet-had-airspeed-indicator-problem-on-last-four-flights/10467826

Lion Air jet had problem with airspeed indicator on last four flights, Indonesia officials sayUpdated about 4 hours agoTue 6 Nov 2018, 4:01am
Video: Officials said data from the black box shows the plane's speed and altitude were erratic. (Photo: AP/Tatan Syuflana) (ABC News) (https://www.abc.net.au/news/2018-11-06/black-box-shows-airspeed-indicator-malfunctioned/10468192)Related Story: All Boeing 737 MAX 8 planes in Indonesia will be inspected after crash (https://www.abc.net.au/news/2018-10-31/lion-air-crash-prompts-inspection-of-all-boeing-737-max-8-plane/10450186)
Related Story: Who owns Lion Air and what do we know about its safety record? (https://www.abc.net.au/news/2018-10-30/who-owns-lion-air-and-what-do-we-know-about-them/10445800)
Related Story: Nothing will change despite the latest Indonesian air tragedy (https://www.abc.net.au/news/2018-10-30/lion-air-tragedy-latest-in-long-list-of-indonesia-incidents/10445326)
Related Story: Crashed plane was brand new, but had 'technical issue' on previous flight (https://www.abc.net.au/news/2018-10-30/lion-air-plane-was-new-had-technical-issue-previous-flight/10445270)The last four flights a Lion Air passenger plane embarked upon before its fatal descent into the Java Sea all had a problem with the airspeed indicator, Indonesia's National Transportation Safety Committee has found.Key points:

Data from the black box data recorder shows the jet's speed and altitude were erratic
Indonesia is asking Boeing and air safety authorities in the US how to prevent similar problems in the future
It is still not clear whether the airspeed indicator problem was a mechanical or maintenance issue



Committee head Soerjanto Tjahjono and investigator Nurcahyo Utomo told a news conference that the problem was similar on each of the four flights, including the one on October 29 that killed all 189 people on board (https://www.abc.net.au/news/2018-10-30/lion-air-plane-was-new-had-technical-issue-previous-flight/10445270).

The stunning revelation came after angry relatives confronted the airline's co-founder at a meeting organised by Indonesian officials.

At the meeting, Mr Soerjanto said information downloaded from the flight data recorder was consistent with reports the plane's speed and altitude were erratic.Embed: Lion Air crashed plane tracker map (https://datawrapper.dwcdn.net/zaA9g/3/?abcnewsembedheight=500)

Mr Soerjanto told reporters the safety committee was asking Boeing and air safety authorities in the United States what action to take to prevent similar problems on this type of plane around the world.

"We are formulating, with [the National Transportation Safety Board in the US] and Boeing, detailed inspections regarding the airspeed indicator," he said.

It was not immediately clear whether the reported problem stemmed from a mechanical or maintenance issue, nor whether US authorities would order any checks.

"Whether the trouble came from its indicator, its measuring device or sensor, or a problem with its computer — this is what we do not know yet," Mr Nurcahyo said.

"We don't know yet where the problem lies, what repair has been done, what their reference books are, what components have been removed.

"These are the things we are trying to find out: what was the damage and how it was fixed."https://www.abc.net.au/news/image/10458878-3x2-700x467.jpg (https://www.abc.net.au/news/2018-11-05/woman-cries-at-funeral-of-victim-of-lion-air-disaster,-nov-1-20/10467846)
Photo: A family member cries at the funeral of Jannatun Cintya Dewi, a passenger of the crashed Lion Air flight. (Reuters: Sigit Pamungkas) (https://www.abc.net.au/news/2018-11-05/woman-cries-at-funeral-of-victim-of-lion-air-disaster,-nov-1-20/10467846)

Many families face an agonising wait for missing relatives to be identified.

Police medical experts have received nearly 140 body bags of human remains and have identified 14 victims.

Relatives questioned why the plane had been cleared to fly after suffering problems on its Bali to Jakarta flight on October 28 that included a rapid descent after take-off that terrified passengers.A long list of air safety incidents (https://www.abc.net.au/news/2018-10-30/lion-air-tragedy-latest-in-long-list-of-indonesia-incidents/10445326)https://www.abc.net.au/cm/lb/10445502/data/lion-air-custom-image-data.jpg (https://www.abc.net.au/news/2018-10-30/lion-air-tragedy-latest-in-long-list-of-indonesia-incidents/10445326)
The sadness in the Lion Air crash is that no-one would really be shocked by it — the Indonesian aviation sector has a bad reputation for good reason, writes former Indonesian correspondent Samantha Hawley. (https://www.abc.net.au/news/2018-10-30/lion-air-tragedy-latest-in-long-list-of-indonesia-incidents/10445326)

"Lion Air said the problem was fixed, is it true the problem was cleared?" said Bambang Sukandar, whose son was on the flight.

"If not, technicians in charge must be responsible."

Another man, who identified himself as the father of passenger Shandy Johan Ramadhan, a prosecutor in a district on the island where the flight was headed, said Lion Air had "failed" the families of victims."Since the time of the crisis, I was never contacted by Lion Air. We lost our child, but there was no empathy that Lion Air showed to us," he said.

After the meeting with passengers' relatives, Mr Rusdi left in a hurry, avoiding questions from reporters.

Safety experts have said it is too early to determine the cause of the crash of the flight.

Authorities have yet to recover the jet's cockpit voice recorder from the sea floor, just north-east of Jakarta, where the plane crashed 13 minutes into its flight.

Boeing did not immediately respond to a request for comment.

The US manufacturer has delivered 219 of the 737 MAX jets to airlines around the world. The Lion Air crash was the first involving this type of plane, which was only introduced into service last year.

AP/Reuters

[Switchbait]

There are Memory Items for Airspeed Unreliable, they are simple and result in a stable aircraft.

There are Memory Items for Runaway Stabilizer for when “Uncommanded stabilizer trim movement occurs continuously”, they are also simple and result in a stable aircraft.

For the crowd assuming that the STS somehow caused this thing to go in, the Memory Item for Runaway Stabilizer SHOULD have that covered....

Both defects are honestly not that hard to deal with.

I’m very interested to see the DFDR data, but in the meantime it pays to remember,
“We don’t rise to the level of our expectations, we fall to the level of our training”

[InfrequentFlier511]

I keep wondering about the flight deck asking atc for their speed, when it should be available on the PFD. (I know, UAS, but why think ATC would know any more than you?) *Unless* something took out the PFD - maybe (and I apologize for even thinking it) the lesson of QZ8501 wasn't learned, and actions on the flight deck made a manageable situation much worse. I get the impression here that as long as the structure remains intact and one engine still turns, a 737 can still get you home, but panic can turn a wise man into a fool.

[B-757]

..I can only think of 3 conditions, where a modern jetliner would end up in a high energy descend (provided all flight controls are working normally)..
..Emergency descend, spiral, and out of trim..

..This flight ended similar to the FlyDubai one..Investigators will find out what happened..Meanwhile,

Fly safe
B-757

[olasek]

There are Memory Items for Airspeed Unreliable, they are simple and result in a stable aircraft.

Exactly, I think we are dealing with a lot of hogwash here.
VFR conditions, daytime, what is the problem of flying level even when your airspeed indicators show absurd numbers.
Fix thrust and maintain selected pitch, and you can even look out the windows ...
This accident shapes up to be one of the worst example of pilot's dereliction of duty ... unless something hit this aircraft or there was a bomb, or his wing fell off, etc.

[First_Principal]

This link (https://web.archive.org/web/20030427083626/http:/www.avweb.com/news/safety/183038-1.html) was posted by @Centaurus on one of the Pacific forums.

Perhaps more than any dispassionate report this transcript of the CVR from AuroPeru 603 provides particularly useful insight into how erroneous instrument readings can cause serious havoc in the cockpit, despite thousands of hours of experience. Spoiler: this is a sad and scary read, and it doesn't end well.

I make no personal comment on similarities to the flight under discussion, but others have commented here on such things; this is it from the horses mouth :(

FP.

[Bleve]

... Under VFR - Power, plus attitude equals performance? No matter what the panel is telling you - if the top of the panel is roughly lined up with the horizon, and the thrust levers are at a certain setting, you'll keep flying? ...

This has been discussed already in the thread, but yes P+A=P applies to all aeroplanes, even big jet ones. After the AF447 accident Boeing (and I'm guessing Airbus) rewrote the Unreliable Airspeed checklist and the initial (memory) steps are essentially: turn off the automatics, hand fly and set a Power and an Attitude. This will give you approximately straight and level flight. [ie Piloting 101: Aviate (P+A=P).] Once that is done and you have established safe manual flight, then the analysis and fault finding can begin. In my airline we've been getting regular Unreliable Airspeed scenarios in our Simulator exercises ever since AF447. I'm guessing it's not going to let up for quite some time yet.

The question now appears to be a Human Factors one: Why are crews not recognising Unreliable Airspeed events and applying the correct recovery procedures?

[vilas]

: Why are crews not recognising Unreliable Airspeed events and applying the correct recovery procedures? UAS after takeoff is straight forward procedure. But unreliable speed and complications of STS and feel can be hand full.

[LaissezPasser]

I’m curious what you all read this tea leaf in Ben Otto’s latest WSJ story:But investigators are now focusing on reasons for a subsequent abrupt altitude drop, these people said, followed by the fatal dive. Operation of another flight-control system, called the angle of attack indicator, also is bound to be examined by the probe, according to safety experts. Such devices are critical in telling aviators how high or low an aircraft’s nose is pointing. Angle of attack sensors operate independently from airspeed sensors.

[sSquares]

350 knots at 5000 feet seems indicate that the actual speed was not known by the pilots.

Maybe mining all public domain flight data might inform some useful airline statistics. The data of all four previous flights for this aircraft should indicate the UAS events as described by the investigators.

-comments from armchair-

[Terry McCassey]

Could we have a similar situation to Air Asia 8501; ie inflight fault finding gone awry, a CB pulled at an inappropriate time?
Not entirely similar. The Captain on 8501 cycled the C/B for the FAC which is a big no no in flight. This will do a complete power down and power up of the computer which will, and did, lead to massive control surface displacement after the power was restored.

[double_barrel]

This link (https://web.archive.org/web/20030427083626/http:/www.avweb.com/news/safety/183038-1.html) was posted by @Centaurus on one of the Pacific forums.

.

What am I missing here? These guys called V1 and V2 on the take-off run. Similarly with the infamous Brisbane take-off with pitot covers on.

How is this possible? Can the tape or covers on the pitots stretch enough to compress the air in the pitot to give accurate and consistent speed readings at ground level? That seems very unlikely.

[Bleve]

What am I missing here? These guys called V1 and V2 on the take-off run. Similarly with the infamous Brisbane take-off with pitot covers on.

How is this possible? Can the tape or covers on the pitots stretch enough to compress the air in the pitot to give accurate and consistent speed readings at ground level? That seems very unlikely.

Firstly with Aeroperu 603, it was the static ports that were covered, so the IAS will indicate correctly at the altitude the static ports were covered. During the take-off roll everything appeared and indicated normally, so V1 & V2 calls were OK. Different story once they climbed away from the altitude at which the static ports were blocked.

With MAS in Brisbane with the pitot tubes covered, both pilots observed red flags on their IAS displays. So how could they call V1 &V2? The interim ATSB report gives a clue: When the Captain called the 100 knot IAS check, the groundspeed was 100kts.

[DaveReidUK]

I keep wondering about the flight deck asking atc for their speed, when it should be available on the PFD. (I know, UAS, but why think ATC would know any more than you?)

Sadly, that may have been more of a forlorn hope than an expectation.

To clear up any confusion, it now seems that ATC are unlikely to have had the necessary equipment (specifically EHS) to see JT610's IAS. And even if they did, it wouldn't necessarily have been any more reliable than what the crew's ASI(s) were displaying.

Re groundspeed, ATC would have access to that (probably both the GPS-derived GS being sent by ADS-B and a less accurate PSR-derived GS). Having said that, the crew would have also have had groundspeed in front of them, on both the PFD and ND, again derived from GPS and therefore not subject to any UAS issues.

[B-757]

I really don't understand what is so tricky about maintaining attitude by reference to PFD'S ADI when flying an airliner; even UAS checklists are telling us to do so.


[/QUOTE]..You will after you get more experience..Sounds like you haven´t seen the s**t hit the fan yet..

Fly safe,
B757

[ozaub]

There were many contributing factors in break-up of AirAsia 8501, not least language confusion between Indonesian Captain and French FO. Towards end of CV recording Captain tells FO to “Pull Down, Pull Down”: meaning push! But FO kept pulling back on side stick.Perhaps there was similar language confusion between Indian Captain and Indonesian FO on this Lionair flight. Only the CVR can tell.

[Clandestino]

IYou will after you get more experience..Sounds like you haven´t seen the s**t hit the fan yet..
What will I see? That the shaker and the clacker might go off erroneously & simultaneously? That's what the QRH says and what is practiced in the sim.

Incidentally, the s***s that hit my fans (and props) so far were up to the point of impact contained in the guts of gulls, magpies, swallows and similar.

[CodyBlade]

French Captain and Indonesian FO


The other way round..

[CDRW]

..Works perfect, if you are in VMC conditions..However, it will get tricky, if you are in the clouds and your instruments are giving you false information (as in this case)..Things happen very fast going at 300+ knots..

Fly Safe
B-757
Well you got this nice little instrument often called the Artificial Horizon. If in the clouds, put the nose just above the horizon and wings level. Set a power and wahllah.
Now if that instrument is telling you porkies, combined with UAS, I'm afraid you up the creek without a paddle.

[krismiler]

So far then it looks like an unreliable airspeed problem which wasn't handled correctly and resulted in tragedy. Even back in the 1970s D.P. Davies was complaining in "Handling the Big Jets" about pilots who had forgotten how to fly due to automation, it's far worse these days as progression onto airliners is more rapid and the level of automatics is more advanced.

Today's generation of aviators are taught to operate autopilots virtually from the start and have never developed basic skills on steam driven aircraft. It's routine to engage the A/P a few seconds after lift off and only disengage it a couple of minutes before touchdown. Setting an attitude and a power setting and making adjustments to achieve the required flight path was a basic and essential skill for an earlier generation of pilots but today's crop can largely get away without the old skills, until something goes wrong. It's a sad fact that many airline pilots today are only able to do their jobs because of the level of automation on modern aircraft, they couldn't cope with an aircraft that had to be FLOWN rather than operated.

[phil gollin]

.

Just before the flood of information and supposition starts, may I just note that the confidentiality held regarding this crash and investigation has been very good. Normally on here there is endless discussion regarding leaks and voluminous criticism of the leaks (especially when it concerns certain parts of the world). Thankfully, this time things have proceeded properly, I can only hope it continues whilst the first (and then second, hopefully) recorders are examined.

.

[A Squared]

.

Just before the flood of information and supposition starts, may I just note that the confidentiality held regarding this crash and investigation has been very good. Normally on here there is endless discussion regarding leaks and voluminous criticism of the leaks (especially when it concerns certain parts of the world). Thankfully, this time things have proceeded properly, I can only hope it continues whilst the first (and then second, hopefully) recorders are examined.

.

You mean aside from the photos of the Aircraft logs being published all over the internet?

[B738bbjsim]

You mean aside from the photos of the Aircraft logs being published all over the internet?
I would have expected by now that the logs of the other 3 UAS events would have surfaced too (if they were logged)

[A Squared]

I’m curious what you all read this tea leaf in Ben Otto’s latest WSJ story:


But investigators are now focusing on reasons for a subsequent abrupt altitude drop, these people said, followed by the fatal dive. Operation of another flight-control system, called the angle of attack indicator, also is bound to be examined by the probe, according to safety experts. Such devices are critical in telling aviators how high or low an aircraft’s nose is pointing. Angle of attack sensors operate independently from airspeed sensors.


Not much, seems like stating some pretty obvious general observations for the benefit of those without the aviation background to realize that they're obvious.

[Concours77]

Not much, seems like stating some pretty obvious general observations for the benefit of those without the aviation background to realize that they're obvious.

Not obvious, and not even accurate. In a “vertical” dive, the Angle of attack can be “0”. The Nose is “-90”. AoA is NOT Pitch. (How high or low the Nose is pointing).

[averdung]

So far then it looks like an unreliable airspeed problem which wasn't handled correctly and resulted in tragedy. Even back in the 1970s D.P. Davies was complaining in "Handling the Big Jets" about pilots who had forgotten how to fly due to automation,

You mean the Sperry SP77 was "automation"? Methinks the dear Capt. Davies exaggerated a bit.

[A Squared]

Not obvious, and not even accurate. In a “vertical” dive, the Angle of attack can be “0”. The Nose is “-90”. AoA is NOT Pitch. (How high or low the Nose is pointing).


Really ... you're claiming that at no time during the course of an investigation into an airline accident involving a loss of control and strong evidence of Airspeed Unreliability and possible malfunction of an automated flight stability system, would investigators think to take a look at AoA data? That is an interesting opinion. Fascinating, really. :hmm:

[DaveReidUK]

Really ... you're claiming that at no time during the course of an investigation into an airline accident involving a loss of control and strong evidence of Airspeed Unreliability and possible malfunction of an automated flight stability system, would investigators think to take a look at AoA data? That is an interesting opinion. Fascinating, really. :hmm:

With respect, I don't think he claimed that at all.

He was simply pointing out that the journo had conflated two terms - AoA and attitude - that in an upset may not bear any relation to each other.

In fact I was typing a similar post at the same time, but I was too slow. :O

[A Squared]

What am I missing here? These guys called V1 and V2 on the take-off run. Similarly with the infamous Brisbane take-off with pitot covers on.

How is this possible? Can the tape or covers on the pitots stretch enough to compress the air in the pitot to give accurate and consistent speed readings at ground level? That seems very unlikely.

Well, it should be pointed out again, that the speculation that pitot tube covers might have been left on in the current accident is just that, purely speculative. It hasn't been ruled out, but there's no reason to suggest this was the problem. So, given that, it is entirely possible that in the current accident, the airspeed indication was normal during the takeoff run, and the airspeed unreliability occurred later. It should also be pointed out that we don't know that they called V1 and V2. The CVR has not yet been recovered.

[A Squared]

With respect, I don't think he claimed that at all.

He was simply pointing out that the journo had conflated two terms - AoA and attitude - that in an upset may not bear any relation to each other.

In fact I was typing a similar post at the same time, but I was too slow. :O

Well, yeah Journalist has a "not quite right" idea of what AoA means, I noted that and moved on, I guess if we want to attach a lot of significance to that, we can. I'm not sure what, exactly though. My take on the question to which I was responding was that the poster was asking "what do you think of the announcement that the investigators will investigate the sudden unplanned descent and the AoA data? " Not: "what do you think about the Journalist's ability to accurately describe Angle of Attack"

[double_barrel]

Well, it should be pointed out again, that the speculation that pitot tube covers might have been left on in the current accident is just that, purely speculative..

I was referring to the CVR from the Aeroperu 603 accident which was shown to be due to the static ports being covered. To add complication to this tangle of links and posts, I had misread that report and taken it to say that the pitots were covered. But my comments do also apply to the BNE MAS takeoff with pitot covers on. I remain unclear about how an apparently accurate 100kn speed call was made there.

[GarageYears]

Well, it should be pointed out again, that the speculation that pitot tube covers might have been left on in the current accident is just that, purely speculative. It hasn't been ruled out, but there's no reason to suggest this was the problem. So, given that, it is entirely possible that in the current accident, the airspeed indication was normal during the takeoff run, and the airspeed unreliability occurred later. It should also be pointed out that we don't know that they called V1 and V2. The CVR has not yet been recovered.

And if the reported previous occurrences of UAS (alleged to be on 4 previous flights...) are correct, then I think all would agree that covered pitots for multiple flights seems completely implausible.

- GY

[mross]

The engineers investigated UAS three times and would surely have discovered blocked or disconnected sensors. What is the next most likely cause? How many AoA sensors does the A/C have?

[A Squared]

I was referring to the CVR from the Aeroperu 603 accident which was shown to be due to the static ports being covered. To add complication to this tangle of links and posts, I had misread that report and taken it to say that the pitots were covered. But my comments do also apply to the BNE MAS takeoff with pitot covers on. I remain unclear about how an apparently accurate 100kn speed call was made there.

Ahhh, OK, obviously I though you were speaking of the current LionAir accident. I too am unclear on the BNE MAS incident. Did the PM make the call based on GS? Where is GS displayed on a A330? On the airplane I fly, it's displayed in a location that you're really have to work at it to mistake it for IAS. Or did he make the call based on GS intentionally, because he didn't have an IAS displayed? The preliminary report states that they observed IAS error flags, was that before or after the 100 knot call? It will be interesting to read the final report on that incident.

[DaveReidUK]

The engineers investigated UAS three times and would surely have discovered blocked or disconnected sensors.

One would have thought/hoped so.

But then again, one would have thought/hoped that the engineering response to a warning of a discrepancy between the inputs (either pitot or hydraulic) to the Elevator Feel Computer would have been to investigate those inputs, rather than just cleaning an electrical connector on an 11-week-old aircraft (!) and then confirming that there was no fault in the EFC itself, before signing off the aircraft as fit for flight.

[Mad (Flt) Scientist]

The engineers investigated UAS three times and would surely have discovered blocked or disconnected sensors. What is the next most likely cause? How many AoA sensors does the A/C have?

I don't think we know exactly what is stated here.We 'know' from statements apparently based on initial FDR data (?) that three (immediately?) previous flights showed URA (UAS) tendencies. We don't know that they were investigated as each occurred. The infamous leaked MX log only showed a single write-up. It is surely possible that nothing was written up until the final flight of the day, so MX really only had one (overnight) troubleshooting attempt?

[DaveReidUK]

It is surely possible that nothing was written up until the final flight of the day, so MX really only had one (overnight) troubleshooting attempt?

No.

Leaving aside the many other implications of that suggestion, the aircraft in question only flew two sectors on the day preceding the accident (MDS-DPS-CGK), so it had nightstopped at least twice since the first of the three previous reported UAS events.

[Mad (Flt) Scientist]

No.

Leaving aside the many other implications of that suggestion, the aircraft in question only flew two sectors on the day preceding the accident (MDS-DPS-CGK), so it had nightstopped at least twice since the first of the three previous reported UAS events.

Thanks, I'm not even remotely able to keep up with the info.

Has it been definitively stated that is was the three immediately preceding flights? if it were intermittent over a longer period that's even more insidious.

[DaveReidUK]

Has it been definitively stated that is was the three immediately preceding flights? if it were intermittent over a longer period that's even more insidious.

From USA Today:

"The “black box” data recorder from a crashed Lion Air jet shows its airspeed indicator malfunctioned on its last four flights, investigators said Monday, just hours after distraught relatives of victims confronted the airline’s co-founder at a meeting organized by officials.

National Transportation Safety Committee chairman Soerjanto Tjahjono said the problem was similar on each of the four flights, including the fatal flight on Oct. 29 in which the plane plunged into the Java Sea minutes after taking off from Jakarta, killing all 189 people on board."

The last four flights were:

Denpasar-Manado 27 Oct
Manado-Denpasar 28 Oct
Denpasar-Jakarta 28 Oct
Jakarta-Pangkal Pinang 29 Oct

Lion Air jet's airspeed indicator malfunctioned on 4 flights (https://eu.usatoday.com/story/news/world/2018/11/05/lion-air-crash-plane-had-airspeed-problem-4-flights/1889396002/)

[M68]

One would have thought/hoped so.

But then again, one would have thought/hoped that the engineering response to a warning of a discrepancy between the inputs (either pitot or hydraulic) to the Elevator Feel Computer would have been to investigate those inputs, rather than just cleaning an electrical connector on an 11-week-old aircraft (!) and then confirming that there was no fault in the EFC itself, before signing off the aircraft as fit for flight.

For such a new aircraft (that, I guess, must be under some kind of warranty) is there actually an exchange of maintenance information happening between the airline and Boeing in a (real-)timely manner?
Or does Boeing usually not get to know what problems have occurred and (hopefully) been fixed by the airline's staff, even if it's a recently delivered airplane?

[glad rag]

If this information is verified, then the obvious conclusion is that there was some sort of malfeasance/misfeasance on the part of maintenance people.

And what if they had diligently (https://www.google.co.uk/search?rlz=1C1PRFI_enGB777GB777&q=diligently&spell=1&sa=X&ved=0ahUKEwiM-LSbicHeAhVDF8AKHbSfBOAQkeECCCsoAA) followed the appropriate manufacturer advice and maintenance procedure[s] after each event? And had been unable to reproduce the fault?

I would suggest the firing of the company maintenance manager may be your biggest clue here at present.

"The plane shouldn't have been flying at all." Where is the mel listing for the max btw?

[jolihokistix]

Re: Interesting examples of other similar events, and re: further comments on those but not on the main subject.

Please head with RE:

A Squared's comment above, "Ahhh, OK, obviously I though you were speaking of the current LionAir accident." hits a nerve and prompts me to post this reminder. Often during the course of this thread I see that when comments are made about a separate accident, bringing in little details such as V1, V2 called or not, it confuses the picture for everyone if no immediate indication is given first regarding which scenario they are describing.

In order to avoid non-signposted sidetracks and subsequent confusion.
Not a rule per se, but more manners or common sense?

[Loose rivets]

hear hear. Warping into a different universe mid-puzzle tests even the greatest minds.

[QDMQDMQDM]

Bloomberg reporting Boeing on the verge of issuing a safety alert on the 737 Max series:

https://www.bloomberg.com/news/articles/2018-11-07/boeing-is-said-close-to-issuing-safety-bulletin-on-737-max-jets?utm_campaign=socialflow-organic&utm_source=twitter&utm_content=business&utm_medium=social&cmpid=socialflow-twitter-business

[Organfreak]

Where is the mel listing for the max btw?

http://fsims.faa.gov/wdocs/mmel/b-737-8_rev%200.pdf

[Lord Farringdon]

hear hear. Warping into a different universe mid-puzzle tests even the greatest minds.
Which rather sounds like what those poor sods on JT610 were up against.

[kristofera]

Bloomberg reporting Boeing on the verge of issuing a safety alert on the 737 Max series:

https://www.bloomberg.com/news/articles/2018-11-07/boeing-is-said-close-to-issuing-safety-bulletin-on-737-max-jets?utm_campaign=socialflow-organic&utm_source=twitter&utm_content=business&utm_medium=social&cmpid=socialflow-twitter-business

The second to last sentence in that article is the best bit... "It wasn’t immediately clear if the airspeed issue had any connection with the angle-of-attack matter."

[CONSO]

https://www.wsj.com/articles/boeing-faa-to-issue-safety-alerts-following-lion-air-crash-1541562339?mod=hp_lead_pos3

ByAndy PasztorNov. 6, 2018 10:45 p.m. ET Responding to the Lion Air jetliner crash that killed 189 people in Indonesia last week, manufacturer Boeing (http://quotes.wsj.com/BA) Co. BA 1.24% (http://quotes.wsj.com/BA?mod=chiclets) and U.S. aviation regulators intend to issue twin safety warnings about potentially suspect flight-control software that can confuse pilots and lead to a steep descent of the affected aircraft model, according to people familiar with the matter.The moves are the first public indication that investigators suspect a possible software glitch or misinterpretation by pilots—related to an essential system that measures how high or low a plane’s nose is pointed—may have played an important part in the sequence of events that caused the Boeing 737 Max 8 to plunge into the Java Sea.

Goes on

[Zeffy]

https://www.seattletimes.com/business/boeing-aerospace/boeing-to-warn-737-max-operators-of-a-potential-instrument-failure-that-could-cause-the-jet-to-nose-dive/
​​​​​​ (https://www.seattletimes.com/business/boeing-aerospace/boeing-to-warn-737-max-operators-of-a-potential-instrument-failure-that-could-cause-the-jet-to-nose-dive/)...Pilots are typically trained on how to handle a “runaway trim” situation, said the person briefed on the Boeing bulletin, but that’s with everything else working as it should. In this case, the control column shaking, the stall warning, and the air speed indicator disagreement all combine to create confusion and keep the pilots very busy.

Boeing instructs pilots in the bulletin that if this failure arises, “higher control forces may be needed to overcome any nose-down stabilizer trim.” The instructions go on to say that after stabilization, the automatic trim system on the horizontal tail should be switched off and any trim performed manually...

[aeromech3]

RE: For such a new aircraft (that, I guess, must be under some kind of warranty) is there actually an exchange of maintenance information happening between the airline and Boeing in a (real-)timely manner?
Or does Boeing usually not get to know what problems have occurred and (hopefully) been fixed by the airline's staff, even if it's a recently delivered airplane?

I worked in a Middle Eastern airline which had only 2 score aircraft but started a Defect Control Dept in late 1970's; each departure station would SITA telex the defects to base and these would be reviewed by a senior engineer and advice to Maintenance, they were also loaded into a very basic ATA program which would show on a measles chart repeat entries for investigation (the most frequent being ATA38, bogs basins). Each morning the Boeing and Pratt & Whitney rep would take note of the problems 1st hand from the hand written cardex system; when we joined up with an American Operator, we had a live link through dedicated SITA line to their Maintenance system; when ETOPS arrived this department was further tuned. With LION Air having over 100 Boeing's one would hope they have a monitoring Dept; it is likely that whilst the days of most resident Reps have gone by way of the bean counters exit route, there is now both ACARS and internet and surely manufacturers have similar access to relevant data from such a major airlines but then can only act bi laterally not instantaneously.

[spongenotbob]

https://theaircurrent.com/aviation-safety/boeing-nearing-737-max-fleet-bulletin-on-aoa-warning-after-lion-air-crash/

Wow...

[Rated De]

https://theaircurrent.com/aviation-safety/boeing-nearing-737-max-fleet-bulletin-on-aoa-warning-after-lion-air-crash/

Wow...

That is staggering.
With the weather as observed, daylight and a known history it was difficult to imagine any pilot losing control to the degree that has been surmised.
That a transport category aircraft can enter an 'aggressive dive' that that upon release of the electric trim may commence again ought be a little more than a 'service bulletin'. Given the article references 'only during manual flight', can this trim hard over happen on approach, as a poor soul hand flies an ILS?

[double_barrel]

The repeated uncommanded nose down action can be stopped by deactivating the stabilizer trim system, according to the official. Boeing warns that the stabilizer system can reach its full downward position if not counteracted by pilot trimming the aircraft and disconnecting the stabilizer trim system.

(my underlining)

Does that mean pulling a breaker?
Upon which trim will return to neutral? Or stay wherever it happened to be?

[Eutychus]

Given the article references 'only during manual flight', can this trim hard over happen on approach, as a poor soul hand flies an ILS?

SLF question: so "fly the damn airplane", oft-repeated above, would in this case be the worst possible advice (and was most likely what the luckless crew were trying to do)?

[Rated De]

SLF question: so "fly the damn airplane", oft-repeated above, would in this case be the worst possible advice (and was most likely what the luckless crew were trying to do)?

Yes that was the point.
Following the checklist with the cacophony of noise alerts and aural tones, the luckless souls were supposed to ignore all the noise, and NOT fly manually.
If what is contained in the article is correct, this is beyond a service bulletin and requires an immediate cessation of operations and grounding until the root source of the fault is identified, isolated and rectified.
Give the often repeated mantra of 'commercial viability' the regulatory authorities would appear (again if this article is correct) to be quite happy to throw the luckless pilots flying this junk under the oncoming bus.
It reeks of regulatory capture, with the usual caveat of waiting for the service bulletin to be promulgated.

[Eutychus]

If what is contained in the article is correct, this is beyond a service bulletin and requires an immediate cessation of operations and grounding until the root source of the fault is identified, isolated and rectified.It certainly doesn't encourage me to get on a 737 MAX for the time being.

[Capn Bloggs]

Following the checklist with the cacophony of noise alerts and aural tones, the luckless souls were supposed to ignore all the noise, and NOT fly manually.
If what is contained in the article is correct, this is beyond a service bulletin and requires an immediate cessation of operations and grounding until the root source of the fault is identified, isolated and rectified.
Give the often repeated mantra of 'commercial viability' the regulatory authorities would appear (again if this article is correct) to be quite happy to throw the luckless pilots flying this junk under the oncoming bus.
The QF A330 that took the plunge, twice, didn't result in grounding the fleet, despite the authorities NEVER working out what happened. Airbus came up with a procedure where crews push-button-disabled a particular system.

SLF question: so "fly the damn airplane", oft-repeated above, would in this case be the worst possible advice (and was most likely what the luckless crew were trying to do)?
If you're comfortable handflying and the aeroplane starts doing something in pitch you don't like with, say, full back stick, you trim against it. Or you grab the trim wheel and stop it. Or you engage the AP! My point is, you have to be happy with hand-flying to be able to have spare brain space to try something.

So, is the STS the culprit when the speeds/AoA go haywire?

[A Squared]

From the Seattle Times article (https://www.seattletimes.com/business/boeing-aerospace/boeing-to-warn-737-max-operators-of-a-potential-instrument-failure-that-could-cause-the-jet-to-nose-dive/)

In reference to the faulty AoA data ...

At the same time, it causes an indicator of the minimum speed to tell the pilot that the plane is near a stall, which also causes the pilot’s control column to shake as a warning. And the air-speed indicators on both sides of the flight deck disagree.

Does that mean that it causes the airspeed indicators disagree with each other, or does that mean that the airspeed indicators disagree with the stall warning/stick shaker (but agree with each other) ?

[Rated De]

The QF A330 that took the plunge, twice, didn't result in grounding the fleet, despite the authorities NEVER working out what happened. Airbus came up with a procedure where crews push-button-disabled a particular system.


If you're comfortable handflying and the aeroplane starts doing something in pitch you don't like with, say, full back stick, you trim against it. Or you grab the trim wheel and stop it. Or you engage the AP! My point is, you have to be happy with hand-flying to be able to have spare brain space to try something.

So, is the STS the culprit when the speeds/AoA go haywire?

Yes the QF A330 didn't result in a grounding, nor was the erroneous ADIRU issue resolved. The 'incident' wasn't fatal. One can imagine the pressure bought to bear by both operators and manufacturers on the regulator was substantial.
In this case, 189 souls were lost.
In a different era perhaps prudence would prevail.

[DaveReidUK]

https://theaircurrent.com/aviation-safety/boeing-nearing-737-max-fleet-bulletin-on-aoa-warning-after-lion-air-crash/

Wow...

Ostrower's piece appears to be an embroidered rehash of the Bloomberg article.

Based on his previous abysmal reporting of the tech log issue ("the perilous unreliability of Lion Air documents"), I think that waiting for independent confirmation of his "additional reporting" might be prudent.

[SigWit]

The QF A330 that took the plunge, twice, didn't result in grounding the fleet, despite the authorities NEVER working out what happened. Airbus came up with a procedure where crews push-button-disabled a particular system.


If you're comfortable handflying and the aeroplane starts doing something in pitch you don't like with, say, full back stick, you trim against it. Or you grab the trim wheel and stop it. Or you engage the AP! My point is, you have to be happy with hand-flying to be able to have spare brain space to try something.

So, is the STS the culprit when the speeds/AoA go haywire?


No, it is not the speed trim system. It is the regular autopilot trim system that commands the nose down trim in case of approaching stall AOA.

Probably the previous crew encountered the same problem and mistakenly wrote it up as a STS fault.

[Derfred]

That’s interesting, I’m pretty sure the NG does no such thing. Can anyone post how this works on the Max?

[Deepinsider]

Now that it's shaping up to include a stab trim issue, there is a parallel discussion going on
on the tech forum which may interest some on the STS issues.
https://www.pprune.org/tech-log/614997-b-737-speed-trim-system-3.html

I've never seen a 737 MAX, does it still have the stab trim wheels? (https://www.pprune.org/tech-log/614997-b-737-speed-trim-system-3.html)

[Denti]

That’s interesting, I’m pretty sure the NG does no such thing. Can anyone post how this works on the Max?
Actually, the NG does:

The EFS module increases hydraulic system A pressure to the elevator feel and
centering unit during a stall. This increases forward control column force to
approximately four times normal feel pressure. The EFS module is armed
whenever an inhibit condition is not present. Inhibit conditions are: on the ground,
radio altitude less than 100 feet and autopilot engaged. However, if EFS is active
when descending through 100 feet RA, it remains active until AOA is reduced
below approximately stickshaker threshold. There are no flight deck indications
that the system is properly armed or activated.
As airspeed decreases towards stall speed, the speed trim system trims the
stabilizer nose down and enables trim above stickshaker AOA. With this trim
schedule the pilot must pull more aft column to stall the airplane. With the column
aft, the amount of column force increase with the onset of EFS module is more
pronounced.

That is from a by now pretty old NG FCOM, i haven't been typed for the last three years on the 737.

That said, we had a few AoA malfunction on our 737 fleet, thank god the only serious thing that happened was a runway overrun without injuries due to different speed indications during take off (abort close to indicated V1, but probably way above V1). In flight the problems caused by the AoA were actually quite severe, indications for IAS, Altitude, VS, flight path vector, wind indication and ground speed all became unreliable on the affected side. Comparator warnings were not always generated, so it was usually detected by pilots saying "this doesn't look right" and then comparing indications across the flight deck. Most problems happened in mid to high altitudes though, so there was plenty of space to recover. And it might or might not have any relevance to the current case.

[kevleyski]

Gizmodo and Bloomberg reporting that fatal nose dive issue is known with the new 737 and what pilots should do at high speed stall.
(can’t post link)

[Derfred]

Thanks Denti. I was aware of the elevator feel input in a stall, and have experienced it in the Sim. Pull the aircraft into a stall and try to hold it in the stall, the back pressure becomes VERY heavy. That’s the elevator feel “anti-stall” in action.

But I wasn’t aware of any “anti-stall” stab trim operations, other than the STS simply doing it’s normal STS thing.

Is the Max different?

[SigWit]

Thanks Denti. I was aware of the elevator feel input in a stall, and have experienced it in the Sim. Pull the aircraft into a stall and try to hold it in the stall, the back pressure becomes VERY heavy. That’s the elevator feel “anti-stall” in action.

But I wasn’t aware of any “anti-stall” stab trim operations, other than the STS simply doing it’s normal STS thing.

Is the Max different?


No, the max trims down just as the 737NG trims down. The post you quote is from a 737NG FCOM and clearly states it trims down.

[wiedehopf]

From the Seattle Times article:

And the air-speed indicators on both sides of the flight deck disagree.


Now i do understand a malfunctioning AoA sensor sensing high AoA would make the red/black band come up on the speed tape (and activate the stick shaker)

But the IAS being displayed should still be correct? Which would technically not be UAS or IAS disagree at all?

Anyone have a guess if this is a compound issue or the UAS issue was not an UAS at all just interpreted that way?

[longlegs]

Who can share a copy of the Bulletin?737 Max angle-of-attack sensor subject of Boeing bulletin

07 Nov 2018 19:29 GMT+10:00
Flight Global

Boeing has issued an operations manual bulletin to 737 Max operators, covering air data sensors, following investigations into the crash of Lion Airflight JT610.

The manufacturer says it issued the bulletin on 6 November, directing operators to “existing flight crew procedures" to address circumstances involving erroneous angle-of-attack sensor information.

Angle-of-attack information is critical to avoiding the onset of stall conditions.

Indonesia's National Transportation Safety Committee has indicated that the ill-fated flight “experienced erroneous input" from such a sensor, says Boeing.

It stresses that issuing bulletins or recommendations, when appropriate, regarding the operation of its aircraft is a "usual process".

“The investigation into Lion Air flight 610 is ongoing and Boeing continues to co-operate fully and provide technical assistance at the request and under the direction of government authorities investigating the accident,” the manufacturer adds.

Media reports had earlier surfaced saying that Boeing was preparing to issue a service bulletin to Max operators.

The NTSC has said that it believes the crashed aircraft had been operating with airspeed indicator faults during its last four flights. It also called on Boeing and the US National Transportation Safety Board to take necessary action to prevent future cases of faulty flight system readings.

Flight JT610 had been operating from Jakarta's Soekarno-Hatta International airport to Pangkal Pinang when it crashed into the sea near the town of Karawang, claiming the lives of all 189 occupants.

[NSEU]

It also called on Boeing and the US National Transportation Safety Board to take necessary action to prevent future cases of faulty flight system readings.

Seriously? Make an aircraft which defies the laws of physics and never breaks down? 3 independent pitot-static systems isn't enough?

[phil gollin]

.

IF this is a software/coding problem, does that mean that the whole flight control system will need to be re-certified as if the checks missed one (huge) error what else might have been missed ?

Well, at least the lawyers will make lots of money out of this tragedy.

.

[averdung]

Seriously? Make an aircraft which defies the laws of physics and never breaks down? 3 independent pitot-static systems isn't enough?

Enough for the National Team of Scaredy Cats? Are you kidding? These are the people that make the FAA look sensible, rational, even daring.

[TURIN]

IF this is a software/coding problem, does that mean that the whole flight control system will need to be re-certified as if the checks missed one (huge) error what else might have been missed ?

If it was all fly by wire then maybe. My understanding is that it's only the spoilers that are electrically signalled. The rest of the system is cables, pulleys and hydraulics.

[Volume]

Boeing warns that the stabilizer system can reach its full downward position if not counteracted by pilot trimming the aircraft and disconnecting the stabilizer trim system.
So is it time to re-introduce all the deleted posts regarding stabilizer trim and elevator efficiency and early jet aircraft design (which the 737 still is over wide areas) ?

Otherwise I am still confused about the different messeges you receive....
- "UAS", which mainly means a pitot issue
- "Faulty speed and altitude indications", which more points to a static pressure issue
and now finally
- "angle of attack sensor subject", which is a totally different system altogether

If we are confused, the pilots probably have been as well...

Now i do understand a malfunctioning AoA sensor sensing high AoA would make the red/black band come up on the speed tape (and activate the stick shaker)
But the IAS being displayed should still be correct? Which would technically not be UAS or IAS disagree at all?
Well, whether the red/black band comes up on the speed tape or the speed goes down (due to UAS), both would reduce the margin between indicated airspeed and calculated stall speed, which may then trigger the stick shaker and the nose-down auto-trim, if the algorithm is made this way...
.

[SLFinAZ]

This issue existed on this specific plane for multiple flights prior to the accident flight. The previous flight was hand flown by the FO (my understanding) so it was a manual approach and landing which would have required multiple power settings and configurations as well as a continual ongoing trimming of the aircraft. So what would make this flight different?
I keep coming back to the combination of level flight (vs. the normal climb out) and the presence of an engineer (in cockpit?). My understanding is that SOP would be for power and pitch to be set such that a stabilized climb rate would be maintained while the non memory items on the checklist were performed...since this didn't happen and a mayday/pan wasn't called
I'm speculating that the decision to maintain (or try to) 5000 ft. was tied somehow to the engineer. Multiple oscillations and variable flight path....got to believe that the interaction of the engineer and crew will be a critical component of what happened and that the breach of the sterile cockpit doctrine will be central to how events unfolded.

[B738bbjsim]

Now that we have AOA in the spotlight, and reports of indicators issue on other Lion 737 Maxx, what could be the cause? The sensor itself, the computer monitoring and converting its readings, or the software converting those readings for interpretation by the STS, among other things??

Can the FDR parameters disclose this? Also, AOA gauge on the PFD was an option on the NG. Is it still an option on the Max, and does Lion have it?

[Suastiastu]

.

Just before the flood of information and supposition starts, may I just note that the confidentiality held regarding this crash and investigation has been very good. Normally on here there is endless discussion regarding leaks and voluminous criticism of the leaks (especially when it concerns certain parts of the world). Thankfully, this time things have proceeded properly, I can only hope it continues whilst the first (and then second, hopefully) recorders are examined.

.

Professionalism through experience unfortunately

[Capn Bloggs]

Also, AOA gauge on the PFD was an option on the NG. Is it still an option on the Max, and does Lion have it?
What use would it be if, as it appears, the AoA system was putting out duff gen? A dud AoA gauge would just confuse the crew even more.

[Volume]

So what would make this flight different?
Some maintenance was done in between. Which may have made things worse if curing the wrong symtoms...

This report will make interesting reading purely from a human factors point of view
I just hope real human factors specialists will be involved in writing it. For sure this will have many very interesting aspects.

I wonder if when the nose dropped each time, this motion caused an illusion that the aircraft had just entered an actual stall.
Especially as the reduction in g load would have been much stronger than any simulator can do, further creating confusion and raising adrenalin levels. The body of most persons reacts vilently to reduced g, and most large aircraft pilots experience it very seldom, not even in the sim.

You are incorrect that action led to a “massive control displacement.”
There has been an (still unexplained) rudder deflection, not large in numbers but still quite massive at cruise speed, which made things significantly worse.

[mross]

ABC News reports that the AoA sensors were replaced before the second-to-last flight https://abcnews.go.com/International/wireStory/boeing-jet-crashed-indonesia-key-sensor-replaced-59028450

Also, from Channel NewsAsia

Soerjanto Tjahjono, head of Indonesia's National Transportation Safety Committee told reporters that after one flight from Bali to Jakarta - the last flight before the crash - the left and right AOA sensors were found to disagree by 20 degrees.

https://www.channelnewsasia.com/news/asia/indonesia-lion-air-crash-boeing-issues-advice-over-sensors-10905532

[Volume]

The Boeing website (http://boeing.mediaroom.com/news-releases-statements?item=130327) is surprisingly clear...
The Indonesian National Transportation Safety Committee has indicated that Lion Air flight 610 experienced erroneous input from one of its AOA (Angle of Attack) sensors.
Quite a different issue compared to UAS...

[Denti]

The Boeing website (http://boeing.mediaroom.com/news-releases-statements?item=130327) is surprisingly clear...

Quite a different issue compared to UAS...
From my own experience on the NG a wrong AoA input will result in UAS, unreliable altitude, vertical speed, wind information and ground speed display. It is a basic correction factor into the ADIRU that does effect all resulting air data related information and surprisingly the non air data related information of ground speed as well. It might be different in the MAX, but somehow i doubt it. As different airflow over the fuselage results in huge position error values for static and pitot tube values, the AoA vane corrects those very different position errors, therefore a wrong AoA indication will result in a completely unreliable air data set.

[Concours77]

Volume.

Quote:
You are incorrect that action led to a “massive control displacement.”
There has been an (still unexplained) rudder deflection, not large in numbers but still quite massive at cruise speed, which made things significantly worse.

<<<<<<>>>>>>

Mod please delete if this is too arcane.

UAS. Some interesting similarities here to another UAS that ended badly.

Subject a/c experienced UAS, followed by warnings and Stall Warning. Pilot initiated (mistakenly) Stall recovery for approach, not high altitude, pull back stick to maintain altitude and increase power. AP switched off, but the CVR audio had the sound of AP switch being cycled by pilot, which is prohibited by airframer. “might lead to control loading leading to failures”.

When found, Rudder showed position of four degrees right, the max deflection allowed by RTLU, (Rudder limiter). Flight path reconstruction showed chronic right roll, and drift, consistent with this deflection in rapid uncontrolled descent.

Pilots ignored Stall Warnings, (there were many).
Subject aircraft type had experienced unexplained and uncommanded nose overs, that were recovered, prior.

Basically a case of aircrew not being familiar with, or untrained for, aircraft “idiosyncrasies”? Different type from this one, but both started with UAS.

Subject accident had major Trim issue. Trim controlled by automatics, they missed it as Trim ended up Full Nose Up, seemingly unknown by crew.

UAS was less well mitigated back then. It didn’t even have an acronym, but needed to be written out tediously when referenced. “UAS” was first used in that discussion, probably by lazy typing averse poster?

Subject aircraft had no AoA (display) installed, and was without a standby Airspeed display, both available at delivery, but not purchased.

Much discussion of “just fly Pitch, and Power”.

[Rananim]

Boeing warns that the stabilizer system can reach its full downward position if not counteracted by pilot trimming the aircraft and disconnecting the stabilizer trim system.

All manufacturers build planes with anti-stall devices.Airbus goes a step further and actually wont allow the stall(normal law).Boeing just warns and aids the pilot to prevent it.Stick shakers,EFS,PLI,the old stick pushers,autoslat,automatic trimming nose down etc etc....all used to help the pilot not stall.All very useful devices.Until you get unreliable pitot-static data(incl AoA).Then these devices can work against you.
What can the pilot do?What can the manufacturer do?
The pilot must know when there is a mismatch between reality and perception(training....airmanship....alertness).The pilot must then follow the QRH memory items and religiously disregard the warnings,disable any stall protection system that affects flight control surfaces( and the only one here is trim) and fly the plane(really not that difficult).EFS doesnt affect flight control surfaces per se it just makes it harder to pull and easier to push.Shakers are tactile warnings.PLI and the like are visual warnings.In the B737 its just the trim thats now working against your control of the ac.
The manufacturer must install these anti-stall devices for certification but cant,as some wise soul above said,prevent pitot-static errors from occurring.Life isnt like that.Errors occur.
Until they come up with something better than the pitot-static system,all they can do is provide data to the pilots in the FCOM and QRH on how to recover from the situation.Somebody a while back posted a picture of a Fokker 100 center pedestal panel(right next to the pilots) showing circuit breakers for overspeed/shaker.This is a very nice design IMO.Its so nice that perhaps it should be an industry standard(with provision of course that switches be protected by covers that have to be flipped by the pilot before they can be activated.... as shown in the Fokker 100 photo)Even with training and good airmanship,the need for crews to disable spurious warnings(the loud aural and tactile warnings that add to confusion) is of paramount importance,especially so if the UAS event is of longer duration.The manufacturer can also refrain from burying pertinent data in the AMM and start to include it in the FCOM.

[.Scott]

Quote:
You are incorrect that action led to a “massive control displacement.”
There has been an (still unexplained) rudder deflection, not large in numbers but still quite massive at cruise speed, which made things significantly worse.

Do we really know that there was a significant "rudder dieflection"? With airspeed just a bit above the maneuvering speed, a pull-up into a full stall is dangerous but semi-benign - it would cause the G force to exceed the rated 2.5G - but only briefly and not by much. But combined with a rudder deflection, it becomes a snap roll. A snap roll is not really a roll. It's a powerful horizontal spin.
I've done snap rolls in a Citabri with a header tank.

[Sailvi767]

This appears to be a simple bent or bad AOA probe giving a erroneous stall warning. Poor jetway operation is the usual cause of a bent probe. I have had it on a L1011 and 727 plus several military aircraft. It’s a no brainer to handle on a non FBW aircraft. You know you are not stalling based on airspeed, attitude, power and phase of flight. Disconnect the electrical trim and fly the aircraft. When time permits pull the stick shaker circuit breaker. What is hard to understand is why over 4 flights this was not diagnosed or fixed. You wonder if the pilots or mechanics even knew the stall warning comes off the AOA probe.

[A Squared]

. What is hard to understand is why over 4 flights this was not diagnosed or fixed. You wonder if the pilots or mechanics even knew the stall warning comes off the AOA probe.


Well, you're assuming that one of the symptoms was an unambiguous stall warning. I don't recall that it was written up in the trip log. from memory, I seem to recall the squawks were for an unreliable airspeed indication and an incorrect activation of the pitch trim. That's a little different than: "There we were, tooling along at M0.8, level at 360 and and suddenly the stall warning sounded and the stick shaker activated." That pretty clearly points to a possible AoA data problem, the way it was actually written up, much less so.

[A Squared]

.... and surprisingly the non air data related information of ground speed as well.

Yes, that is surprising. How does AoA data affect Groundspeed, and why?

[GarageYears]

Has anyone seen the Boeing issued bulletin?

The Boeing media room confirms such a bulletin has been issued: MediaRoom - News Releases/Statements (http://boeing.mediaroom.com/news-releases-statements?item=130327)

At this point I don't understand whether this is a MAX issue or a 737 recent generations issue (i.e. MAX and NG variants).

Any clarification appreciated.

- GY

[Water pilot]

Although not an (air) pilot I was an engineer. This one is entirely on the engineers. The AoA sensor was replaced the day before the fatal flight. I really should not have to expand on why flying passengers on a plane that has exhibited multiple critical failures of an unknown cause is a bad, perhaps even criminal course of action. This was being treated like a lemon car at a dealership is often treated -- "well, try replacing the sensors and see if that helps." That can be a bad idea even for a passenger car (and has led to lawsuits when the car crashes) but when you have hundreds of lives thousands of feet in the air it is beyond unacceptable. Even though the likes of Microsoft and Apple seem to have forgotten it, there is a thing called "testing" which you should do before a fix goes live. It is very easy to make things worse.
It was probably a bad wiring harness, and no amount of new sensors will fix that.

[DingerX]

That "journalistic" website that doesn't like to cite sources claims to have posted the bulletin in question:
The Indonesian National Transportation Safety Committee has indicated that Lion Air flight 610 experienced erroneous AOA data. Boeing would like to call attention to an AOA failure condition that can occur during manual flight only.

This bulletin directs flight crews to existing procedures to address this condition. In the event of erroneous AOA data, the pitch trim system can trim the stabilizer nose down in increments lasting up to 10 seconds. The nose down stabilizer trim movement can be stopped and reversed with the use of the electric stabilizer trim switches but may restart 5 seconds after the electric stabilizer trim switches are released. Repetitive cycles of uncommanded nose down stabilizer continue to occur unless the stabilizer trim system is deactivated through use of both STAB TRIM CUTOUT switches in accordance with the existing procedures in the Runaway Stabilizer NNC. It is possible for the stabilizer to reach the nose down limit unless the system inputs are counteracted completely by pilot trim inputs and both STAB TRIM CUTOUT switches are moved to CUTOUT.

Additionally, pilots are reminded that an erroneous AOA can cause some or all of the following indications and effects:

- Continuous or intermittent stick shaker on the affected side only.
- Minimum speed bar (red and black) on the affected side only.
- Increasing nose down control forces.
- Inability to engage autopilot.
- Automatic disengagement of autopilot.
- IAS DISAGREE alert.
- ALT DISAGREE alert.
- AOA DISAGREE alert (if the AOA indicator option is installed)
- FEEL DIFF PRESS light.

In the event an uncommanded nose down stabilizer trim is experienced on the 737-8 /-9, in conjunction with one or more of the above indications or effects, do the Runaway Stabilizer NNC ensuring that the STAB TRIM CUTOUT switches are set to CUTOUT and stay in the CUTOUT position for the remainder of the flight.

In short, bad AOA data is sufficient to cause the reports of UAS and STS acting backwards. The maintenance writeups implicitly made a diagnosis, and it looks like nobody down the line went back to the causes and inferred the problem. For that matter, go back and read the discussion here and see what was said about the AOA sensors. It's still a head-scratcher.
And, to reply to a comment from pages above, no this is not a case where "just hand-fly" would be the worst thing to do. The sensor failure kicked off the automatics, and there was no choice. The guidance in the bulletin is a "reminder" of the procedure to follow if the aircraft is trying to trim the nose into the ground.

[infrequentflyer789]

This appears to be a simple bent or bad AOA probe giving a erroneous stall warning. Poor jetway operation is the usual cause of a bent probe. I have had it on a L1011 and 727 plus several military aircraft. It’s a no brainer to handle on a non FBW aircraft. You know you are not stalling based on airspeed, attitude, power and phase of flight. Disconnect the electrical trim and fly the aircraft. When time permits pull the stick shaker circuit breaker. What is hard to understand is why over 4 flights this was not diagnosed or fixed. You wonder if the pilots or mechanics even knew the stall warning comes off the AOA probe.

Yes, except this (https://www.channelnewsasia.com/news/asia/indonesia-lion-air-crash-boeing-issues-advice-over-sensors-10905532) article (from further up the thread) states that the "broken" AOA sensor was replaced. Apparently they are sending it back to mfr for examination, presumably to find out how it caused a crash whilst not even on the aircraft... :confused: Does seem to mean that the earlier leaked maintenance reports that didn't mention AOA sensor were at best misleadingly incomplete. Also there is the possibility that the wrong sensor got replaced, or multiple duff sensors.

From the same article we also have (in relation to previous flight): "The pilot's success became our reference to give a recommendation to Boeing so they could issue an advice for other airlines to follow the same procedures if the same situation occurs,"

while on Boeing (http://boeing.mediaroom.com/news-releases-statements?item=130327) site it basically says "refer to existing procedures" - which is sort of implying that the crash pilots didn't follow them.

Also when comparing to L1011 & 727 era, need to remember that it's no longer three independent sets of sensors feeding three sets of gauges, but rather three sets of sensor inputs all going into multiple redundant ADIRUs which decide/calculate the "correct" data outputs, which can then be fed to either PFD. Any one sensor input being wrong could (by design, it shouldn't, but...) give incorrect or invalidated data on any output from any/all ADIRUs - it all depends on ADIRU internal logic. AF447 threw up some "interesting" ADIRU logic at high (actual) AOA, similar may apply at erroneously-high sensed AOA.

[rideforever]

The pilot must know when there is a mismatch between reality and perception(training....airmanship....
In this kind of event, "solving" the problem in the air with passengers on board is the wrong approach.
Better to disengage all automatic systems and fly manually until the flight is complete.
End of.
Fighting with the computer, which might or might not be working properly, or programmed properly, or the procedures which might or might not take into account this situation etc... this is a a game you will lose.
Uproot the problem land the plane, argue later.
In this era of .... a wish to reduce crew costs and bring in more computing .... with so many financial agendas behind the machines and procedures, simplify everything land the plane.

[Volume]

How does AoA data affect Groundspeed, and why?
Not groundspeed, but indicated airspeed....

In a nutshell: total pressure is constant wherever you have airflow, hence you can place a pitot tube at any location where you have attached airflow, if the probe roughly points into the airflow, it will work satisfactory.
Measuring static pressure only works in places, where the airflow has exactly the same speed as the aircraft. If you would measure static pressure on the upper wing surface, you would actually measure the low pressure which keeps you in the air. Also on the nose fuselage, you have slightly increased airflow speed, an your static pressure is too low. Towards the end of the fuselage your airflow may be more the same as the general airspeed, but the turbulent boundary layer of the fuselage would create some high frequency pressure variations. So it is very, very hard to find a proper place for the static probe.
If you place the static probe in a position where the additional speed due to the airflow around the fuselage is well known, you may correct the measured pressure electronically. This obviously happen here, static pressure measurement is AoA sensitive, so you measure AoA to correct your static pressure.
This way, an AoA failure results in unreliable static pressure, hence UAS and unreliable altitude. Additionally your AoA driven stall warning goes havoc...

Not so nice if you are sitting in row 0.

[FIRESYSOK]

The way I read this is : Pilots May have had erroneous air data (caused by faulty AOA sensor) on one side, causing multiple miscompare messages.

Confusing start..

Autopilot may not have been available; the bulletin saying STS may continue to trim nose-down to prevent a stall condition during manual flight.

(With those messages why wouldn’t the software automatically inhibit the STS?)

Either a false stick pusher activated, or the crew was fighting an ever-worsening out-of-trim condition which resulted in enourmous stick forces they could no longer handle? Both?

All the above my speculation, of course.

[ImbracableCrunk]

I've often wondered this, and maybe it could help: Why not go in to CWS when faced with UAS? Set the pitch (4deg or 10deg) via CWS and set the N1 (75% or 80%)?

[Water pilot]

Please remember this if you are one of the many fine Men and Women whom I sometimes trust with my life. A failure in a new plane is an even more serious matter than a failure in an old one, and you should refuse to fly it until the flaw with the plane -- and how confident you are that they have really discovered the true flaw --- is explained to your satisfaction. This is true of any complex system; each successful "flight" is a proof that there isn't a large underlying flaw in the construction. A 30-year-old house that shows drywall cracking and uneven floors is a far different matter than a one-month-old house with exactly the same symptoms to the same degree. There is a lot of stuff on a plane that will never go wrong if it was initially assembled correctly, so there really are not procedures to deal with an incorrect assembly.
Unless you always fly by hand, a programmer could design avionics that could kill the best of you. Obviously the engineers try very hard to keep people alive rather than kill them, but there is this guy called "Murphy" lurking in the background. One person in South Carolina has a bad day and puts the blue wire in the red slot or maybe a knife slips and "whew! It looks good, I don't have to redo that entire bundle" and the air gap between the wires is large enough that it doesn't cause a short on the dry day that the plane was tested...

[Concours77]

MtIn this kind of event, "solving" the problem in the air with passengers on board is the wrong approach.
Better to disengage all automatic systems and fly manually until the flight is complete.
End of.
Fighting with the computer, which might or might not be working properly, or programmed properly, or the procedures which might or might not take into account this situation etc... this is a a game you will lose.
Uproot the problem land the plane, argue later.
In this era of .... a wish to reduce crew costs and bring in more computing .... with so many financial agendas behind the machines and procedures, simplify everything land the plane.

Bravo...

Seems to me human pilots are in the cockpit to aviate. Automation is not in our DNA. Butt cheeks, intuition, training, and a sceptical approach to a cacophony of alerts, grabbing the manual, and trying to suss the computer instead of simply.....aviating. “What’s it doing now?” Is the road, literally, to ruin.

Unless and until AI commands pushback and what follows, the human/automatics interface will be a skirmish, not a collaboration.

Which infers that the interface of choice would be between automatics, and manual reversion. These types of horrors teach us that basic flight was quite possible, what killed these people was a stubborn reliance, ego driven, on man’s supremacy over man, via digital “solutions.” (sic)

After AF447, any fatality caused by Autotrim should be treated as homocide.

[Flutter speed]

Not groundspeed, but indicated airspeed....

In a nutshell: total pressure is constant wherever you have airflow, hence you can place a pitot tube at any location where you have attached airflow, if the probe roughly points into the airflow, it will work satisfactory.
Measuring static pressure only works in places, where the airflow has exactly the same speed as the aircraft. If you would measure static pressure on the upper wing surface, you would actually measure the low pressure which keeps you in the air. Also on the nose fuselage, you have slightly increased airflow speed, an your static pressure is too low. Towards the end of the fuselage your airflow may be more the same as the general airspeed, but the turbulent boundary layer of the fuselage would create some high frequency pressure variations. So it is very, very hard to find a proper place for the static probe.

If you place the static probe in a position where the additional speed due to the airflow around the fuselage is well known, you may correct the measured pressure electronically. This obviously happen here, static pressure measurement is AoA sensitive, so you measure AoA to correct your static pressure.
This way, an AoA failure results in unreliable static pressure, hence UAS and unreliable altitude. Additionally your AoA driven stall warning goes havoc...

Not so nice if you are sitting in row 0.

The link between AoA and indicated airspeed is not so obvious. As part of my profession I get to see a lot of the internals of modern Air Data / Inertial Navigation systems. And without going into detail, the correction from AoA for the static pressure is minimal (other corrections like ground effect, reverse thrust etc are more pronounced and still small). If AoA is way off, it seems more likely a miscompare is triggered between AoA1 and AoA2. This could have all kinds of consequences and warnings which on a 737 probably need to be recognized by a pilot an actively worked (i.e., manually switch Air Data source of affected side to standby or opposite).
Agree with the stall warning, the amber band etc will be all over the place.

edit: link (http://www.boeing.com/commercial/aeromagazine/aero_12/aoa.pdf) to Boeing Aero magazine regarding AoA indication on Boeing aircraft.

[WillFlyForCheese]

Now that we have AOA in the spotlight, and reports of indicators issue on other Lion 737 Maxx, what could be the cause?

My understanding is that the reports of “issues” are not on other Lion aircraft - but multiple flights of the same aircraft.

[wiedehopf]

So inhibiting the anti-stall trim system on AOA or other air data disagree would seem like a sensible thing to do?

Can Boeing even do that now without being sued?

[Concours77]

So inhibiting the anti-stall trim system on AOA or other air data disagree would seem like a sensible thing to do?

Can Boeing even do that now without being sued?

Let’s look at precedent. What did Airbus do as a result of AutoTrim full up to and through Stalll?

[A Squared]

How does AoA data affect Groundspeed, and why?


Not groundspeed, but indicated airspeed....

In a nutshell: ...blah, blah,blah, blah, blah,blah, blah, blah,blah ....
Not so nice if you are sitting in row 0.

Look my friend, if you had bothered to read the post I was responding to, you would have seen that the poster had stated that AoA would affect airspeeed but surprisingly, in addition to affecting airspeed (which I understand just fine, thank you ) it *also* affects groundspeed. I'll quote for you (again) the post I was responding to, so that you might have another chance to read it, perhaps with better comprehension this time.

. It is a basic correction factor into the ADIRU that does effect all resulting air data related information and surprisingly the non air data related information of ground speed as well. .

So, once again, for Denti, yes it's surprising that AoA affects groundspeed and I'd be interested to have that explained.

[FIRESYSOK]

Boeing has already said it can be dealt with with ‘existing procedure’.

[DaveReidUK]

Not groundspeed, but indicated airspeed....

Except that the author of the quoted post took pains to stress that both airspeed and groundspeed values are affected by unreliable AoA, in fact GS was mentioned twice in that context:

From my own experience on the NG a wrong AoA input will result in UAS, unreliable altitude, vertical speed, wind information and ground speed display. It is a basic correction factor into the ADIRU that does effect all resulting air data related information and surprisingly the non air data related information of ground speed as well

I look forward to learning how so.

[Water pilot]

The nose down stabilizer trim movement can be stopped and reversed with the use of the electric stabilizer trim switches but may restart 5 seconds after the electric stabilizer trim switches are released.
Jesus. So while you are fighting the other symptoms of UAS, the plane is quietly trying to kill you.

[A Squared]

I've often wondered this, and maybe it could help: Why not go in to CWS when faced with UAS? Set the pitch (4deg or 10deg) via CWS and set the N1 (75% or 80%)?

It might work, but if the airplane is actively fighting your efforts to keep it in stable flight via uncontrollable erratic trim inputs, you might be reluctant to believe that engaging the A/P in any mode would help, and you might be right.

[Concours77]

Jesus. So while you are fighting the other symptoms of UAS, the plane is quietly trying to kill you.

Airbus. same. Only reversing trim is done manually, and wheel must be held to retain new position. If one lets go the wheel, the aircraft reloads, and tries to kill again.