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Air Asia Indonesia Lost Contact from Surabaya to Singapore

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Air Asia Indonesia Lost Contact from Surabaya to Singapore

Old 1st Jan 2015, 17:35
  #881 (permalink)  
tuj
 
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@gums - your posts are real gems, thanks for your insight. I have read them with great interest back in the AF447 days.

Back to the subject, if this Captain was the PF, do you have any idea what type of training he would have received in the Indonesian Air Force? I would think that a fighter pilot would regularly be on the edge of the flight envelopes, but perhaps this is not true with a 2nd-world Air Force? Perhaps his training was limited to bombing runs and BVR interception?

I can't shake the notion that the Captain should have been someone with a chance to recover the plane, having familiarity with FBW and sidestick controls. He certainly wouldn't have 'stirred-the-muck' like the AF447 inputs.

Perhaps one question is, is this another story of the THS going into NU and then the crew forgetting about it when the automatics cut out?
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Old 1st Jan 2015, 17:42
  #882 (permalink)  

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lapp

You might like to consider post 859 re piloting similarities between extreme turbulence and loss of airspeed.
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Old 1st Jan 2015, 17:48
  #883 (permalink)  
 
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Originally Posted by slats11

An interesting question. What altitude would you like tracked? FL as per altimeter? GPS derived altitude (when available)? Both?

Imagine if we had both and there was a sudden substantial discrepancy. Imagine how useful it would be in a case when it was going to takie time to get the recorders (deep mid pcean).

As an aside, how often is GPS coverage sufficient to permit altitude to be calculated.
This is an interesting question.

GPS provides a 3D position, it is just that only the 2D position is used normally.
GPS is used (as one would expect) by GPS Landing Systems that provide the vertical as well as lateral guidance. These are made more accurate by ground based augmentation systems (GBAS) but the accuracy is of the order of 8 meters in all directions without GBAS but with wide area augmentation systems (WAAS).

If everyone flew on GPS altitude then the huge (and they are worryingly huge) number of errors caused by mis-set altimeters would go away.

Currently aircraft in cruise follow a pressure level based on 29.92 / 1013 which means as they fly into a low pressure area they descend and in high pressure areas they climb. Crossing some fronts will mean a descent followed by a climb. However, this is keeping them at the same pressure level so might be better for engine economy but that may be lost if the engines reduce thrust in the decent toward a front then increase thrust to climb away from the front.

Some aircraft are using GPS to provide backup speed information by continually cross referring GPS calculated ground speed to airspeed so if the airspeed indicators drop out the GPS system can provide a reasonable airspeed figure.

So expect to see satellite based altitude and speed information continue to creep into aircraft systems.
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Old 1st Jan 2015, 17:57
  #884 (permalink)  
 
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You might like to consider post 859 re piloting similarities between extreme turbulence and loss of airspeed.
We have zero knowledge about what happened in this case.
There is zero evidence that the two accidents are even just similar.

Keep banking your drum of hate against a plane maker, and keep making a fool of yourself.
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Old 1st Jan 2015, 17:57
  #885 (permalink)  
 
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And it's not just 'Asian' crews. Some of the folks I fly with still think it is an entitlement to play video games and watch movies on their tablets while at the controls. After NW 188 overflew MSP five years ago and the feds pulled the pilots' tickets some of this stuff died down but now it's getting worse, not better in my observation.

I started to say something but it was a long trip ahead and some of these folks act like you've taken away their birthday if you mildly imply that the captain is in command. I guess it's a generational culture thing.


Since you are from TN we may have flown for the same airline. Saw a marked difference when I went to the left seat. Stuff I would never do as a F/O without asking the captain happens all too frequently. On a domestic flight, first leg the F/O (PM) pulls out a book at cruise. Next leg F/O (PF) pulls out said book prior to the transition altitude. I tell him to put it away and he ends up pouting for the rest of the trip.
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Old 1st Jan 2015, 17:59
  #886 (permalink)  
 
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"I have control" is good, but a response of "you have control" is even better. Makes sure everyone is on the same page. It's been a long time since I crewed on a heavy, but I remember that even back circa 1980 the response had pretty much fallen out of use.
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Old 1st Jan 2015, 18:22
  #887 (permalink)  
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Ian W : Ah the famous debate between GPS and baro altitude! Just like enbedded lateral off-set on FMS , those are wonderful ideas but full of hidden (good) reasons not to do it.
Heavily debated during the ICAO FANS meetings, , if my memory is correct ( long time ago !) main reason against was that WGS84 ( the GPS reference ) is a spheroidal while earth is irregular (a "potatoidal" was the name used) and therefore not suitable in some parts/areas of the world.

Another one was that , at the time , the GPS precision mode switch was still in the hands of the US military , and also in addition, many States would not accept to depend solely on it.
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Old 1st Jan 2015, 18:33
  #888 (permalink)  
 
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for example noting that acoustic ping search has, for now, failed
Somewhat worrying that the head of the search effort is quoted by the South China Morning Post article as saying that they are hoping to detect the ELT underwater.

Hopefully just a misquote and he really means the recorder ULBs.
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Old 1st Jan 2015, 18:34
  #889 (permalink)  
 
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You can't get AoA or airspeed from INS.

surely, GPS is absolute and doesn't have to be integrated. Based on that you can even get GS, but airplane doesn't care about GS at all.

AoA vanes and pitot tubes are the only direct measurements of those crucial parameters that can be obtained.
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Old 1st Jan 2015, 18:53
  #890 (permalink)  
 
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Originally Posted by ATC Watcher
Ian W : Ah the famous debate between GPS and baro altitude! Just like enbedded lateral off-set on FMS , those are wonderful ideas but full of hidden (good) reasons not to do it.
Heavily debated during the ICAO FANS meetings, , if my memory is correct ( long time ago !) main reason against was that WGS84 ( the GPS reference ) is a spheroidal while earth is irregular (a "potatoidal" was the name used) and therefore not suitable in some parts/areas of the world.

Another one was that , at the time , the GPS precision mode switch was still in the hands of the US military , and also in addition, many States would not accept to depend solely on it.
Indeed, but as you say that was a long time ago. Things have moved on significantly since then. The ellipsoid corrections to geoid are taken care of by software corrections for example.

(For the technical: The World Geodetic System 1984 (WGS84) datum surface is defined as an oblate spheroid or ellipsoid, with major transverse radius at the equator. The coordinate origin of WGS-84 is the center of mass of the Earth. This is being replaced in some applications by the Earth Gravitational Model of 1996. The EGM96 geoid varies from the WGS-84 ellipsoid by between +85 and -105 meters. This can be corrected by software with errors reduced to centimeters
see

Evaluation of EGM96 geoid model in the U.S.
The CARIB97 high resolution geoid height model for the Caribbean Sea
Tutorial: The Geoid and Receiver Measurements | Education | UNAVCO
)

We are also now in the position that ATC surveillance is based on GPS (or rather satellite based positioning - includes GLONAS, Galileo etc.). As it is one of the little recognized aspects of the move to ADS-B and C reports for the basis of aircraft tracking that the Air Navigation Service Providers are now becoming reliant on GPS.
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Old 1st Jan 2015, 18:53
  #891 (permalink)  
 
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The only sustained input nose up was between about 2:11:40 and 2:12:30. But even before that started the THS had trimmed full up, and it was game over.
You seem to dismiss this pilot input as inconsequential. Any sustained nose-up input for nearly a full minute in which auto-trim engages is reckless, no?
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Old 1st Jan 2015, 18:56
  #892 (permalink)  
 
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"Would the automatics eventually recover from any condition resulting from a jet upset? Stall/Spin? Inverted?"

Unlikely, since there are an too many permutations of logical states. In other words - the system is too complex to cover for all possible outcomes.

The only definitive proof that it could would lie in math field - prove it in math - it is 100% guarantee,

One counterexample also - Bus stall warning shutting itself below 60kt threshold, since the AoA readings rendered invalid/inacc. I doubt designers predicted/ thought about that )
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Old 1st Jan 2015, 18:57
  #893 (permalink)  
 
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Angel Ernie Gann had the answer . .

from his book FATE IS THE HUNTER paraphrased somewhat and extracted in describing crashes ..

At these times, Gann says, "... diligently acquired scientific understanding is suddenly blinded and the medieval mind returns. In describing NTSB investigations of crashes, a cause always has to be arrived at, even when the investigators privately know that the true explanation is that "...some totally unrecognizable genie has once again unbuttoned his pants and urinated on the pillars of science".
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Old 1st Jan 2015, 18:58
  #894 (permalink)  
 
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French Copilot p2f background

Here's the gentleman's background. He was a graduate of a very tough engineering university (CalTech or MIT level), held managerial post at TOTAL, then indeed p2f. Not taking sides in this debate, just providing info:

"Quand la filiale de la compagnie malaisienne est venue, en 2012, en Espagne chez CAE Global Academy organiser des sélections de pilotes de ligne, l’APPAG a présenté les élèves de sa première promotion qui venaient de terminer leur cursus. Rémi Plésel a fait partie des candidats. Ils ont été six à être retenus par Air Asia Indonesia. Ils ont signé un contrat de trois ans. Le quadragénaire totalisait alors 850 heures de vol, affirme son ami. Des heures qu’il avait financé lui-même, avec son salaire, pour entretenir ses qualifications. « Il allait souvent voler aux Etats-Unis ». Il a notamment effectué son mûrissement au pilotage à l’école de pilotage de la compagnie aérienne Delta Airlines, à Sanford (Floride)."

Vol QZ 8501 : Rémi Plésel, un copilote engagé - AéroBuzz : Actualité et Information Aéronautique
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Old 1st Jan 2015, 19:01
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Originally Posted by Sunamer
You can't get AoA or airspeed from INS.

surely, GPS is absolute and doesn't have to be integrated. Based on that you can even get GS, but airplane doesn't care about GS at all.

AoA vanes and pitot tubes are the only direct measurements of those crucial parameters that can be obtained.
What you say is true - as an instantaneous measurement. But if for a period of time I have ground speed and track from GPS and airspeed from a pitot tube then I can calculate the ambient windspeed and direction. If the pitot sensed airspeed drops out - I can generate and display an airspeed based on the ground speed from GPS and the previous windspeed and direction. In most cases this will be near enough to provide the pilot with sufficient useful information. Add the pilot selecting the appropriate 'pitch and power' for cruise to that and in most instances the information is sufficient to recover the aircraft. This is on the assumption that there will not be gross changes in wind speed/vector in the short period of time before the air driven sensors come back on line.
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Old 1st Jan 2015, 19:12
  #896 (permalink)  
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We are also now in the position that ATC surveillance is based on GPS (or rather satellite based positioning - includes GLONAS, Galileo etc.). As it is one of the little recognized aspects of the move to ADS-B and C reports for the basis of aircraft tracking that the Air Navigation Service Providers are now becoming reliant on GPS.
On the horizontal plane, absolutely ,( GNSS is the "politically correct" term ), but the altitude part of ADS is still derived from Mode S transponder altitude, whose encoder is barometric, and unlikely to change in our lifetime if you ask me .
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Old 1st Jan 2015, 19:26
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lapp

We have zero knowledge about what happened in this case.
I was under the impression that the aircraft was flying towards a known band of weather, had asked for a level change and shortly after this contact was lost.

In my first post and for the benefit of non pilots I was simply outlining the piloting actions I was taught (many moons ago) in the event of encountering extreme turbulence or loss of airspeed indication.

If you see that as me banging a drum of hate I can only apologise for confusing you.
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Old 1st Jan 2015, 19:33
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I can generate and display an airspeed based on the ground speed from GPS and the previous windspeed and direction. In most cases this will be near enough to provide the pilot with sufficient useful information. Add the pilot selecting the appropriate 'pitch and power' for cruise to that and in most instances the information is sufficient to recover the aircraft.
You are assuming 2 things; that SatNav gives horizontal speed and ignores vertical speed components and that SatNav is unaffected by environmental aspects such as electrical weather systems. Existing Integrated INS gyros do all this successfully in vehicles such as submarines to space craft.
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Old 1st Jan 2015, 19:46
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Just like enbedded lateral off-set on FMS , those are wonderful ideas but full of hidden (good) reasons not to do it.
Lateral offset is SOP these days in the SLOP program, not sure why you wouldn't want to do it. A good overview here: https://ivao.aero/training/documenta...P_SEC_SLOP.pdf

Also, you almost always get lateral offsets flying in Chinese airspace, I don't see how you could avoid them. These offsets seem somewhat random and are not always to the right side. Sometimes you even get them on SID's and have to invoke some FMS magic to make them work.
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Old 1st Jan 2015, 19:48
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"I have ground speed and track from GPS and airspeed from a pitot tube then I can calculate the ambient windspeed and direction"

Right, but it is not the same as getting airspeed from GS, since in that case you have to get GS(gps velocity), last wind readings and you have to have a really nice INS that would give precise enough acceleration measurements (not INS for 150$) so that when you feed all that stuff into some sort of soph. alg (kalman filter or smthg), you would get correct(more or less) "airspeed" reading.

In the lab that I am working in (university lab - aerospace/engineering dept) we got INSsa that cost 10 times as $150 and it's not as precise for supporting that kind of model of obtaining airspeed as it should be.

What I was arguing about is -> $150 might not be enough.
-------------------------------------------------------------

"If the pitot sensed airspeed drops out"
caution - conditions that determine that "drop out" might be vague.
It is probably easier to let this thing to be decided by a pilot.
-------------------------------------------------------------

If am not mistaken, at least B787 have that mode in which it derives airspeed from gps and (I am assuming, by using INS too). In that video the difference in airspeed and calculated "airspeed" was around 5 kts. But, again - not with a $150 solution )
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