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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 12th Jan 2015, 16:07
  #1841 (permalink)  
 
Join Date: Mar 2014
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@Livesinafield: "I think 3km is a lot I'm sure a 6kt current can't move 20kilos of metal that's sat in the sand"

At 6kt that distance represents about 20 minutes - if one of two pieces sinks straight away after surface impact and disruption, and the other floats for 20 minutes before sinking carried by a current flowing at that speed, that does not seem particularly unrealistic?
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Old 12th Jan 2015, 16:08
  #1842 (permalink)  
 
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I would not bet on that. Diver and sailor here - the amount of force 6 knots of current exerts on a large and light metal object is immense.
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Old 12th Jan 2015, 16:30
  #1843 (permalink)  
 
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Modern airborne radar is better than the "crap" we had 30 years ago? Surely you jest.

I could see the control tower on an airport from 5 miles out with the old radars, I could see individual airplanes parked on the ramp. I could see the weather clearly and make my own decisions as to the amount of water carried by parts of the cloud and thus make my own decision as to the parts to avoid. I flew years and years in the tropics and experienced hundreds of severe encounters at some of the worst levels (around 13,000 to 15,000 feet).

I give you the new radars are easy to use and they do the deciphering for you, but often they are wrong and always exaggerate. They are useless for fine work, cannot do even a small part of what was done by the older radars. They are cheaper to buy and to maintain, and are much lighter, so I see the reason for them, but don't kid yourself that they are better for the purpose they were built.
No Boofhead, I do not jest. They were crap.
I cut my ITCZ teeth on B732's in West Africa in the early 80's. My prevailing memory of those old radars was dodgy unreliable displays, lots of twiddly knobs to play with, and the definite impressioin that half the time they were serving you BS. Maybe because my crusty old Captains weren't 'adept' enough at twiddling the knobs. Or maybe because it was a black art that required a lot of concentration to work right - the kind of time you don't always have when racing around at 500mph in a storm filled sky.

Indeed a pair of my colleagues were almost killed by one of those cranky boxes. They made the mistake of interpreting a gap in the display as a hole. It was in fact a 'Super Cell', blanked out by radar attenuation. The aircraft was almost a write-off. The damage was impressive.

C Band Radar requires larger antennae, and other heavier equipment (so I'm told) so other solutions would be developed by necessity. The new radars do not require anything like the artistry of the old systems to give you useful info. When you say 'pilots don't know how to read/operate their radar' and instead recommend a return to those prehistoric glow tubes of old - you are being a bit of a luddite, nothing more. There is every likelihood such a system would create more problems than solutions. So I'll keep my modern, stabilised, bright, colour contoured, computer enhanced, map overlaid MODERN Wx radar thanks. If you want you can always switch off the automatics and play away to your hearts content with the raw data, ground clutter, noise, and all the other rubbish.

The bottom line is - the new stuff shows the weather very well in my experience. You use it to avoid - not penetrate CB's. Doing otherwise is the only possible explanation I can come up with for your love of those old boxes.
Good luck.
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Old 12th Jan 2015, 16:44
  #1844 (permalink)  
 
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All or most of the pax will have died from the same cause, so a few autopsies should be enough.
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Old 12th Jan 2015, 16:47
  #1845 (permalink)  
 
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Are you sure the super-cell would not be black on a new radar too? Very early on with the monochrome digital radar we had back in the day, we learne the black blobs in the middle of the green returns were the worst areas to fly, not holes in the storms. The physics of extreme rain absorbing the radio waves has not changed.
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Old 12th Jan 2015, 17:00
  #1846 (permalink)  
 
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Correct.
Also with modern radar, any black area surrounded by Red is to be acoided at all times as this is probably an area where the data is invalid due to much precipitation...

On some models, this is supposed to be depected by magenta, not on the radars I operate though.
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Old 12th Jan 2015, 17:03
  #1847 (permalink)  
 
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Large ships and some boats will fit S band radar that can burn through heavy rain, but the antennas would never fit anything but an AWACS airplane.
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Old 12th Jan 2015, 17:03
  #1848 (permalink)  
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Originally Posted by sAx_R54 View Post
@TWheels

Your sure of this are you.....less to do with SOP??
The airline I worked for in Indonesia welcome the engineer to sit in the jumpseat, but if they weren't required to be there to troubleshoot a problem, then they usually chose to sit in the cabin unless, of course, when we were full and they had no choice. On such occasions, I got the impression they felt uneasy being in the cockpit, which I suspect is due to the authority gradient.
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Old 12th Jan 2015, 17:11
  #1849 (permalink)  
 
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3km, explosive

Tail section carried 3km is believable only if the tail was down current from the FDR. When we see current direction overlaid on a map of FDR and tail section locations it will be clear enough. Or more puzzling if the tail was cross stream or upstream.

I don't know anyone who does not with hindsight regret their choice of words from time to time, especially when in front of a crowd or on camera. I don't yet see anything contradictory in the 'explosive..air pressure' statement'. Sounds may be mis-interpreted, so must be considered separately. But a high volume, high velocity intrusion of seawater midpoint into a mostly horizontal fuselage could be expected to result in some cabin air overpressure. The paper bag analogy remains viable. Do recall also the fuselage frame pic of the skin neatly unzipped from the intact frame. The most likely cause of that is a sudden, very large, very uniform internal pressure. One must come up with an alternate cause for the unzipped skins to be able to disregard a fuselage overpressure. The video of the fuselage in situ which also shows virtually all cabin contents absent suggests a significant force having removed them.
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Old 12th Jan 2015, 17:19
  #1850 (permalink)  
 
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Originally Posted by despegue View Post
Correct.
Also with modern radar, any black area surrounded by Red is to be acoided at all times as this is probably an area where the data is invalid due to much precipitation...

On some models, this is supposed to be depected by magenta, not on the radars I operate though.
And remember that these radars regardless of their age are showing the rain which is mainly in the cold downdrafts. Warm updrafts will show a lot weaker on the radar but the turbulence will be as bad as the rainy downdraft and sudden changes in OAT can confuse the ADIRUs.
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Old 12th Jan 2015, 17:27
  #1851 (permalink)  
 
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Do any airliners fit stormscopes or equivalent technology? One of their selling points was that lightning was found in turbulent air, heavy rain or not. I liked the one I had way back when. Not as accurate as radar, but it worked.
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Old 12th Jan 2015, 17:34
  #1852 (permalink)  
 
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Reading FDR

Numerous news reports about the recovery of QZ8501's flight data recorder say it might take up to a month to read the data. Can anyone tell me if this is true and why it takes so long, especially if the FDR is intact, as this one seems to be?
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Old 12th Jan 2015, 17:46
  #1853 (permalink)  
 
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No professional investigator or materials engineer would be confused by scrapes or scratches from the recovery effort.
As a professional aviation investigator and materials engineer I concur with peekay4's comment.

Moreover, I think it is important to not overplay the significance of the airframe impact damage. Think about what happens when an aircraft impacts land rather than water. Events X, Y and Z occur at altitude, leading to aircraft loss with ground impact. There will often be massive deformation, tearing and even burning of the airframe as a result of the ground impact. For the most part there is not a lot of significance that can be attributed to the somewhat random large-scale airframe damage caused by ground impact, other than determining things such as approximate speed, attitude and angle at impact (I'm in no way saying that impact damage and ground witness marks are unimportant, just that for the most part these are a consequence of a chain of preceding events that are often more significant to the investigation). Despite extensive ground impact damage, the evidence of what occurred is still there to be found, and far more often than not the factors leading up to the accident will be determined by the investigation team.

It is not easy hauling damaged airframes out of water without causing additional deformation and damage. My point is that some salvage-induced damage is not likely to be a big deal w.r.t. determining what happened with this flight.
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Old 12th Jan 2015, 17:49
  #1854 (permalink)  
 
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island airphoto,
I can remember being struck by lightning in a clear blue sky when flying out of Tel Aviv - no turbulence and not a cloud in the sky! Lightning in thunderstorm is not associated with turbulence in the same that way that water droplets are.
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Old 12th Jan 2015, 17:49
  #1855 (permalink)  
 
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island_airphoto

Are you sure the super-cell would not be black on a new radar too? Very early on with the monochrome digital radar we had back in the day, we learne the black blobs in the middle of the green returns were the worst areas to fly, not holes in the storms. The physics of extreme rain absorbing the radio waves has not changed.
The old radars were monochrome. So how did you tell the difference between attenuation caused by a super cell and an actual gap? You couldn't. Well, maybe if you were highly skilled in the black arts you might be that kind of genius who just COULD tell the difference. Black holes didn't always appear neatly ensconced in the centre of green blobs. In the event I referred to the guys reported no green contour - just a nice clear (black) gap between the green blobs. A sucker hole.

With a modern contoured radar what would you expect to see in the same scenario?
A green contour, followed by a yellow contour, followed by a red contour, maybe some purple - then, what? A hole? Blackness?
Well it might depend on your radar set, but my suggestion is you don't go near RED or PURPLE, and try your best to avoid YELLOW and GREEN too.
That'll keep you safe.
No guesswork or black art required.

PS Radar attenuation is part and parcel of the system. If a sufficiently strong beam is emitted it could pass through all weather giving no returns. Not much good for WX spotting.
The signal needs to be of just the right strength to be partially reflected thus showing the WX. The snag is the weaker beam also suffers attenuation.
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Old 12th Jan 2015, 17:54
  #1856 (permalink)  
 
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Stormscope

Island Airphoto:

Yes, I remember flying around with a Stormscope, they detect static electricity from moving air currents, not necessarily lightning, and so are pretty good at telling you where the rough air might be... especially at low level, but I would expect a Stormscope would be overworked in an area of multiple active CBs - just too many dots! They were mostly intended for light - non radar - aircraft. I never flew a heavy aircraft with one.
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Old 12th Jan 2015, 17:59
  #1857 (permalink)  
 
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Originally Posted by Leightman 957 View Post
Tail section carried 3km is believable only if the tail was down current from the FDR. When we see current direction overlaid on a map of FDR and tail section locations it will be clear enough. Or more puzzling if the tail was cross stream or upstream.

I don't know anyone who does not with hindsight regret their choice of words from time to time, especially when in front of a crowd or on camera. I don't yet see anything contradictory in the 'explosive..air pressure' statement'. Sounds may be mis-interpreted, so must be considered separately. But a high volume, high velocity intrusion of seawater midpoint into a mostly horizontal fuselage could be expected to result in some cabin air overpressure. The paper bag analogy remains viable. Do recall also the fuselage frame pic of the skin neatly unzipped from the intact frame. The most likely cause of that is a sudden, very large, very uniform internal pressure. One must come up with an alternate cause for the unzipped skins to be able to disregard a fuselage overpressure. The video of the fuselage in situ which also shows virtually all cabin contents absent suggests a significant force having removed them.
Any fuselage "overpressure" would be caused by the force of water entering the cabin, and nothing to do with air pressure. Air easily compresses, water does not.
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Old 12th Jan 2015, 18:00
  #1858 (permalink)  
 
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Algol - we used to try and get a ground return on the far side of the storm to see if it was a hole or heavy rain and then tilt up to get an idea how hight the tops were. It was far from foolproof with the small antennas on a piston twin, sometimes you just had to keep away from all of it or heavy rain where you were would blind you to what was coming. I suspect that is still true - heavy enough precip where you are right now won't let you see very well if even worse is in front of you.
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Old 12th Jan 2015, 18:00
  #1859 (permalink)  
 
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Has this been posted before? Video that shows a rear door on the tail: BBC News - Navy releases new underwater footage of AirAsia plane


Last edited by Lost in Saigon; 12th Jan 2015 at 18:14.
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Old 12th Jan 2015, 18:04
  #1860 (permalink)  
 
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Lessons from AF447

I don't yet see anything contradictory in the 'explosive..air pressure' statement'. Sounds may be mis-interpreted, so must be considered separately. But a high volume, high velocity intrusion of seawater midpoint into a mostly horizontal fuselage could be expected to result in some cabin air overpressure. The paper bag analogy remains viable. Do recall also the fuselage frame pic of the skin neatly unzipped from the intact frame. The most likely cause of that is a sudden, very large, very uniform internal pressure. One must come up with an alternate cause for the unzipped skins to be able to disregard a fuselage overpressure.
Surely the impact that occurred with AF447 would be a good model for an intact aircraft hitting the ocean at relative high vertical speed? I do not recall there being anything that might have been described as some kind of cabin over-pressure 'explosion' due to water ingress. It seems very unlikely that the aircraft would hit in a sufficiently flat attitude, that would avoid a structural break up at critical stress points - meaning there would be no intact pressure vessel to "over-pressure".
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