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Indonesian aircraft missing off Jakarta

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Indonesian aircraft missing off Jakarta

Old 31st Oct 2018, 14:20
  #301 (permalink)  
 
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Originally Posted by Winnerhofer View Post
Boeing which is participating in the probe, has privately expressed an interest in whether the pilots received unreliable speed data and about the maintenance history of the plane, according to people familiar with the conversations.
It will be interesting to see if any maintenance was performed on the radar in the day(s) preceding the accident.
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Old 31st Oct 2018, 14:32
  #302 (permalink)  
 
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Originally Posted by Winnerhofer View Post
Boeing which is participating in the probe, has privately expressed an interest in whether the pilots received unreliable speed data and about the maintenance history of the plane, according to people familiar with the conversations.
Great information!!!!! What are the odds that an Aircraft manufacturer would be interested in the maintenance history of one of their crashed products. That must be the smoking gun, right there!!!!
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Old 31st Oct 2018, 14:36
  #303 (permalink)  
 
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Originally Posted by thomasfo View Post
Any reason the pitot tube covers are not made with a weak spot and with a 'parachute' so they would just rip off at takeof speed? Sounds like a $1 solution to a repeating problem.
A number of reasons, one of the simplest is so that they don't get blown off in a storm.

Another is that it will make people skip the checks, statistically only slightly more often than with "non-parachute" covers, knowing (maybe unconsciously) that they'll blow off anyway. And then maybe the "little $1 parachute" fails ...

Lack of total air pressure data is noticeable on the takeoff roll long before V1, and should be an immediate criterion to reject the takeoff. There are numerous speed call-outs on aircraft with multiple pilots, things like "airspeed alive", "80 knots" (and/or "100 knots"), "Vee One" and "Rotate", all based on indicated airspeed. Some of these calls need to be acknowledged by the other pilot after cross-checking the speed indication on the instrument on his side, usually with something like "(80 knots,) checked". A discrepancy will cause a reject.

This is a matter of a safety culture, that procedures and safety awareness are in place and pervasive (although this is not something that can be created overnight). An airline where it can happen that multiple checks for pitot covers fail has a deeper problem with its organisational culture.

Small ad-hoc technical fixes may seem to be the solution to a specific problem, but they may also distract from a deeper problem. If it can happen that pitot covers remain undetected, what else will be regularly overlooked on pre-takeoff checks? A takeoff with pitot covers, while rare, is not only a serious issue in itself, but also a symptom of much deeper problem.

Bernd
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Old 31st Oct 2018, 14:45
  #304 (permalink)  
 
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The Pitot covers don’t explain the sudden vertical dive. I’m not seeing how the two are connected.

It would be more plausible had the numbers shown a sudden climb before dive indicating stall due poor handling of incorrect speeds. But it just fell.
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Old 31st Oct 2018, 14:56
  #305 (permalink)  
 
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Media reporting pilot experience:

https://www.ndtv.com/india-news/lion...-good--1940308

31 yr old CA got his licenses from Bel Air flight school in California 2009 and hired at Lion Air in 2011. Of the 6000 hrs the overwhelming majority are at Lion Air.
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Old 31st Oct 2018, 15:03
  #306 (permalink)  
 
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Originally Posted by DaveReid
It will be interesting to see if any maintenance was performed on the radar in the day(s) preceding the accident.
I'll bite. Why?
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Old 31st Oct 2018, 15:13
  #307 (permalink)  
 
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Originally Posted by Nemrytter View Post
If anyone actually cares about the quality of various ADS-B sources then this is worth a read, in German unofunrtately but google translate does an OK job: https://www5.in.tum.de/pub/Zintl2017_BA.pdf
A good read, thanks. I wonder how well his model holds up for abnormal attitudes.

My guess is: not at all, seeing the various iterations they had to go through to get even normal flight attitudes roughly right (i. e. good enough to look plausible when seen from a kilometre away).

Bernd
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Old 31st Oct 2018, 15:19
  #308 (permalink)  
 
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Originally Posted by Flyer1015 View Post
Media reporting pilot experience:

https://www.ndtv.com/india-news/lion...-good--1940308

31 yr old CA got his licenses from Bel Air flight school in California 2009 and hired at Lion Air in 2011. Of the 6000 hrs the overwhelming majority are at Lion Air.
I believe Lion Air may have had an agreement with Eagle Jet back in those days to 'employ' low time newbies under some paid 'hour building program'. I'm not saying he was one of those on the program, but it was widely known that such programs existed back then.

Lion air stops recruiting through eagle jet
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Old 31st Oct 2018, 15:29
  #309 (permalink)  
 
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Salute!

@Bloggs

The air data sensors appear to be just behind the radome and access panels for the radar. There's possibility of contamination or even a "loose" pnematic line depending upon the actual configuration of the air data sensors. One plane I flew had the AoA sensors on the radome, so one birdstrike ruined the day for that puppy, as it was full FBW and needed those things to keep the pointy end forward.

WRT manual flying the beast, it seems that unless you turn off stuff, like the trim and feel system, you still have pitch inputs from "Hal". So I am sticking with a loss of control due to the combo of bad air data and possible mechanical failure involving the stab trim.

Gums sends...
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Old 31st Oct 2018, 15:39
  #310 (permalink)  
 
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Originally Posted by Volume View Post
What is most ridulous is that in 1988 most pilots would have easily handled such situation...
There is not really any proof that most pilots can't handle it today. AF447 investigation found 30+ previous similar incidents that were easily handled non-events vs. the one that wasn't handled - surely that is "most" pilots easily handling such situation?

But "most" has never been all - e.g. in 1974 flight NW6231 went down killing all aboard, cause?: pitots iced up, mishandled, stalled...

Modern aircraft rely much more on automation of highly integrated systems and profit from the significaltly higher reliability of the modern systems (electronics vs. electromechanical).
At the same time pilot training has changed from basic flying perfection to efficient procedures and system management, well trained to handle any situation the engineers thought of by the best procedure.
If all goes well, safety figures go up a lot.
It is fundamental that when you engineer a system (hardware, software, training, procedures, the whole thing) to eliminate the failures that are simple, predictable, easy to understand, have happened before, what you end up with is a system that now fails in ways that are complex, hard to understand, unpredictable and new. Hopefully it's overall a safer system than before, but that doesn't always follow.
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Old 31st Oct 2018, 16:00
  #311 (permalink)  
 
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it seems that unless you turn off stuff, like the trim and feel system, you still have pitch inputs from "Hal".
This is the reason why the first 5 or more points on the emergency checklist end with "- OFF".
Autopilot - OFF, Auto Throttle- OFF, Flight Director- OFF etc.

Unfortunately many pilots switch on again those gimmicks as soon as possible to avoid having to fly by hand...
It is sometimes tempting to have the aircraft flying by itself, and to concentrate on troubleshooting.

A topic I never really finally concluded on is what should be the preferred tactics (in general aviation, SEP): Acccept that something has failed, switch off anything related to have a clear status, just fly what is left manually and leave it to a mechanic to fix it after landing. Or troubleshoot in flight to be back to normal as soon as possible. Even for such major events like an engine failure, accept to fly a glider and prepare for the perfect emergency landing (after all I did some 5000 glider landings...), or trying to restart until emergency landing becomes unavoidable. At home in the armchair I am always with tactics one, what I will do if it really happens and I am full of adrenaline, no idea.

Commercial pilots already have that decided by some smart people at the manufacturer, authority and operator. Just follow the trained procedure.
Hopefully they never get into a situation for which no checklist/procedure exists... Or for which the checklist/procedure has been written without ever being tested (a.k.a. the sully situation)

In 1988 most pilots would have easily handled such situation...
With "such situation" I was thinking of loosing all air data in VMC daylight in the airport pattern.
AF447 was a bit more complex, I would not have expected all pilots to have handled that back in 1988... Hand flying in IMC at night in a heavy thunderstorm in the middle of the ocean at FL360 is a bit different from hand flying at 5000 ft.
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Old 31st Oct 2018, 16:21
  #312 (permalink)  
 
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Did they find the FDR and CVR in the meantime? Can‘t be that difficult in 30m tropical water. Without their data all is pure speculation.
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Old 31st Oct 2018, 16:23
  #313 (permalink)  
 
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Originally Posted by DaveReidUK View Post
Reportedly 72 ft (22 m). If it turns out to be part of the aircraft, that's pretty close to the length of half a 737-8 wing with the centre wing box attached.

That could suggest it was no longer attached to the fuselage (and falling considerably more slowly, hence remaining relatively intact) by the time it hit the water.
Hmmm... If we suppose it went in at near 90deg bank, how much would the uppermost wing be shielded from impact forces by the fuselage?

XL888 went down with the wings still attached (pretty sure there was actual video or photos of the event, but can only find simulations now), I can't find detailed info about how large the wreckage pieces were, but the report refers to a "partial wing zone" in the wreckage mapping, and there are pictures of the stab floating in one piece. Half a wing doesn't sound impossible, even if impacting intact.
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Old 31st Oct 2018, 16:39
  #314 (permalink)  
 
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No turn around and and land?

Not a pilot, feel free to delete ...

Absent airspeed indications, I would expect pilots to set throttle and AoA for stable flight, declare an emergency, get an estimation of windspeed from ground, point a Mark I Eyeball out the window on that pointy end, and use the compass, radio altimeter and groundspeed indicators to navigate back to the airfield, and land - surely with a 5mph ground wind, and decent weather, a visual-only landing is a possibility?

I know that flying is hard and requires specialist training but if visual flying of a modern airplane in good conditions at 5000ft has become impossible for trained pilots with 5000 hours, then maybe this is an issue for input to the politicians and not to be left for the industry to bury in the name of "self-regulation"? Or is the "blocked vents ==> mass funeral" scenario now going to be played out every few years?

AF447 was a wake up call on the effects of bad airspeed indications ...

I think those smart guys with sliderules in Seattle and Toulouse are perfectly capable of making planes that can be flown by hand when necessary, provided the customers or supervisory authorities ask nicely.

Edmund

Last edited by edmundronald; 31st Oct 2018 at 16:51. Reason: minor
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Old 31st Oct 2018, 16:47
  #315 (permalink)  
 
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Originally Posted by edmundronald View Post
Not a pilot, feel free to delete ...

Absent airspeed indications, I would expect pilots to set throttle and AoA for stable flight, declare an emergency, get an estimation of windspeed from ground, point a Mark I Eyeball out the window on that pointy end, and use the compass and groundspeed indicators to navigate back to the airfield, and land - surely with a 5mph ground wind, and decent weather a visual-only landing, maybe a bit on the fast side for safety is a possibility?

I know that flying is hard and requires specialist training but if visual flying of a modern airplane in good conditions at 5000ft has become impossible for trained pilots with 5000 hours, then maybe this is an issue for input to the politicians and not to be left for the industry to bury in the name of "self-regulation" -

AF447 was a wake up call on the effects of bad airspeed indications ...

Edmund
SPOT ON EDMUND
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Old 31st Oct 2018, 16:50
  #316 (permalink)  
 
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Edmund
You might be after something ......
Luckily enough you say you're not a pilot because if any old [email protected] would state the same he would be cried down big time ".... wait for the final report, everything is ok with ops and training in this region, no difference between locos and regulars, blah blah ...".

It's early time on this one, i know, but smells a lot in your pointed direction.
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Old 31st Oct 2018, 16:53
  #317 (permalink)  
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spanner point of view...

hard shell Pitot Covers would give you pretty much no airspeed at all, modern covers are made to partially burn through and for sure one of the 3 system would have provided some sort of indication. As they took off at the end, they must have had at least 2 reliable speed signals.
737's do not come with P/S smart probes, therefore I would bet something was wrong with the static ports. As there was some work the night before on the system, the guys might have covered the ports with high speed tape to do do some tests (not really da way to go, but most of the equipment used to cover the static ports are leaking badly). The ports are unpainted and some speed tape is hard to detect if you are complacent or in a rush. If static pressure is missing, that really messes up your indication and you will have no reliable data at all.

as for the ADSB out well not a 737 geek, however the system uses barometric as well as geographical altitude and transmits both. ADSB does not transmit vertical or horizontal airspeed, instead horizontal and vertical velocity ;-)

cheers
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Old 31st Oct 2018, 17:02
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Originally Posted by Volume View Post
This is the reason why the first 5 or more points on the emergency checklist end with "- OFF".
Autopilot - OFF, Auto Throttle- OFF, Flight Director- OFF etc.

Unfortunately many pilots switch on again those gimmicks as soon as possible to avoid having to fly by hand...
It is sometimes tempting to have the aircraft flying by itself, and to concentrate on troubleshooting.

SNIP


With "such situation" I was thinking of loosing all air data in VMC daylight in the airport pattern.
AF447 was a bit more complex, I would not have expected all pilots to have handled that back in 1988... Hand flying in IMC at night in a heavy thunderstorm in the middle of the ocean at FL360 is a bit different from hand flying at 5000 ft.
Worth adding that not one of the three AF447 crew looked at the emergency checklist at all, nor even mentioned it. Easy to say from here, but those OFFs surely would have helped...... (BTW, though it's possible that the PF thought he was in a heavy thunderstorm, he wasn't - they had pretty much avoided it, though clipping its edge brought on the temporary pitot icing that got them and their a/c very confused indeed.)
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Old 31st Oct 2018, 17:16
  #319 (permalink)  
 
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Salute!

ya got it right, Volume. Try to “start over”, if you can. With the current flight control and nav gear systems, that is a challenging task. My systems engineering background and thousands of fighter hours confirm that approach.

With all respect to Edmond, in very rare cases a series of failures and design features result in a condition that all the engineers and test pilots never envisioned. So the “pitch and power” procedure might not work because the damned jack screw for the stab has failed or is stuck.

My heart goes out to the crew, that prolly had to deal with problems they had not been trained for, or maybe no procedure published because the combo of mals couldn’t happen, huh?

Gums sends....


Last edited by gums; 31st Oct 2018 at 17:18. Reason: Typo
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Old 31st Oct 2018, 17:19
  #320 (permalink)  
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Originally Posted by infrequentflyer789 View Post
Hmmm... If we suppose it went in at near 90deg bank, how much would the uppermost wing be shielded from impact forces by the fuselage?

XL888 went down with the wings still attached (pretty sure there was actual video or photos of the event, but can only find simulations now), I can't find detailed info about how large the wreckage pieces were, but the report refers to a "partial wing zone" in the wreckage mapping, and there are pictures of the stab floating in one piece. Half a wing doesn't sound impossible, even if impacting intact.
In 2000, Alaska 261 went down from FL17800 of Port Hueneme, California - into the Pacific - and there were still several large pieces of the airplane recovered - including the engines.

https://www.ntsb.gov/investigations/...ts/AAR0201.pdf

Of course - the angle of entry will dictate what happens to the structure - but I'd nonetheless think they would be some larger pieces recovered.
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