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-   -   Air Asia Indonesia Lost Contact from Surabaya to Singapore (https://www.pprune.org/rumours-news/553569-air-asia-indonesia-lost-contact-surabaya-singapore.html)

Ian W 1st Jan 2015 16:20


Originally Posted by The Ancient Geek (Post 8805031)
Regarding the inadequacies of weather radar in detecting many hazardous conditions there has been a lot of promising recent research using LIDAR.
Meteorologists are very pleased with the ability to better detect convective conditions but this is cutting edge stuff so likely to be many years away from routine use in aviation.

Maybe this will replace our current weather radars in the future. OTOH having a scanning laser on the nose of every airliner may prove to be too hazardous.

There is a problem that LIDAR does not work in heavy rain as the laser signal is too attenuated while the radar signal will work in all but the heaviest rain but is not good at identifying clear air turbulence. The answer in research was that both should be set up together.

Real issue is that turbulence may be rain wrapped or be sitting just the other side of a curtain of rain waiting for you to fly into it. This is where the human interpretation of the storm structure is needed. Honest research meteorologists will admit that this is not a simple problem every storm is different. This is why the rather less than useful advice is to avoid flying close to Cb. In all areas of the tropics and sub-tropics this would stop flying a large proportion of the time. However, it does lend support to the idea of a 'business trajectory' being used rather than fixed routes based on canned plans.

ZAGORFLY 1st Jan 2015 16:26

Weather Radar
 
A great source of wisdom and knowledge is : Archie Trammell
google it ...

Rockhound 1st Jan 2015 16:28

Stall warnings on AF447
 
Roseland,
In reference to your post #857, you are incorrect when you claimed that the stall warnings on AF447 stopped shortly after the captain re-entered the cockpit.
The stall warning sounded a total of 75 times during the fall of AF447 to the ocean. By my count, it sounded 29 times after the captain's return to the flight deck. Not once was it acknowledged by any of the crew.
Rockhound

sAx_R54 1st Jan 2015 16:32


Originally Posted by JoeyBalls:8804780
@ Mixture

well, the safest thing would be to never take off...............................how do you think that will play out?

Also, people keep mentioning the CA was an F-16 pilot, so what? Flying an F-16 is absolutely nothing like flying an Airbus. The only commonality is they both are Yoke-less..............

Well the suggestion maybe that the F16 pilot has spent a significant proportion of his time maneuvering his aircraft to extremis of flight envelope in all conditions. A significant proportion of 20k hour commercial pilot time has been spent accumulating an hours actual flying time in every 9hr sector (e.g 30mins landing 30 mins take-off inc departure from ramp), with maybe 50% of the 'hours on type' spent in a 3 axis motion platform. So maybe just a little more than the yoke!

tuj 1st Jan 2015 16:35

@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?

John Farley 1st Jan 2015 16:42

lapp

You might like to consider post 859 re piloting similarities between extreme turbulence and loss of airspeed.

Ian W 1st Jan 2015 16:48


Originally Posted by slats11 (Post 8805258)

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.

lapp 1st Jan 2015 16:57


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.

Springer1 1st Jan 2015 16:57

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.

PersonFromPorlock 1st Jan 2015 16:59

"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.

ATC Watcher 1st Jan 2015 17:22

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.

DaveReidUK 1st Jan 2015 17:33


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.

Sunamer 1st Jan 2015 17:34

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.

Ian W 1st Jan 2015 17:53


Originally Posted by ATC Watcher (Post 8806088)
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.

formulaben 1st Jan 2015 17:53


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?

Sunamer 1st Jan 2015 17:56

"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 )

SAMPUBLIUS 1st Jan 2015 17:57

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". :suspect:

formationdriver 1st Jan 2015 17:58

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

Ian W 1st Jan 2015 18:01


Originally Posted by Sunamer (Post 8806103)
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.

ATC Watcher 1st Jan 2015 18:12

Ian W

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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