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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 9th Jan 2015, 15:21
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Unhappy re tail detach

" susiser said '
'How likely is it for the FDR to have detached from the airframe if the a/c reached the surface intact?

IF the aircraft was in a nose up- pitch up attitude when it hit the water, IMO the tail section AFT of the pressure bulkhead would hit first and likely to be torn off- thes has to do with the manufacturing joint/join in this area.

and the FDR/CVR might still be with the fusealege section, or totally separated from both. Add in wind and current and a logical area to look would be between the fuselage and tail debris locations.

I'm sure the experts and pros with details of the exact mounting have done a thourough search - but hampered by waves and weather. I have not yet heard of finding for sure the major fuselage section.

Just have to wait and see . . .
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Old 9th Jan 2015, 16:50
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AirScotia:
My physics is rusty, but isn't velocity a product of speed plus direction? A spinning aircraft may not have forward speed, but it does have plenty of changing direction, therefore plenty of velocity. So it will hit the ocean with plenty of energy, I assume?
Linear velocity has a speed and direction component, but they aren't involved in a product that says something about the energy of the system. That would be speed and mass.

Rotational velocity - the rate at which a body is spinning about an axis through its center of gravity - also needs a mass component and its distance from the spin axis to form "angular momentum", which would indicate how badly impacting a fixed object (e.g. the water surface) would damage the rotating body. The accident-investigation experts can pontificate re any signs that occurred here.
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Old 9th Jan 2015, 17:01
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Originally Posted by poorjohn
AirScotia:

Linear velocity has a speed and direction component, but they aren't involved in a product that says something about the energy of the system. That would be speed and mass.

Rotational velocity - the rate at which a body is spinning about an axis through its center of gravity - also needs a mass component and its distance from the spin axis to form "angular momentum", which would indicate how badly impacting a fixed object (e.g. the water surface) would damage the rotating body. The accident-investigation experts can pontificate re any signs that occurred here.
I would suspect that a lot of the direction and loading of the impact is already known by the doctors doing the, albeit brief, autopsy checks on the bodies.

I am certain we will be told when it is thought best to tell us.
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Old 9th Jan 2015, 17:25
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Quote:
Originally Posted by Machinbird
Gents, best pull in your horns. This aircraft impacted with significantly less velocity than did AF447.

Originally Posted by Lonewolf 50
Do you arrive at that provisional conclusion based on the condition of the bits so far found, on the track info available, or both?
Primarily from some of the relatively undamaged seat structure and by the lesser accordion action visible on the structure.
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Old 9th Jan 2015, 17:33
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Ian W sayeth,
I would suspect that a lot of the direction and loading of the impact is already known by the doctors doing the, albeit brief, autopsy checks on the bodies.
Not asking argumentatively, and notwithstanding TV shows such as "CIS," would these doctors have any qualifications for judging such things?
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Old 9th Jan 2015, 18:02
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Just some physics facts about definitions. Terminal velocity is often loosely used to refer to the speed when the force of gravity balances the drag in the opposite direction in freefall. So strictly terminal velocity is a vector in the direction that gravity is pulling, where the magnitude of that vector is the terminal speed that gives a drag force equal numerically to the downward force due to mass of the object being considered.

If you want to consider energy then you can take the linear kinetic energy (mass times the square of the speed) as a major component, but if there is rotation then there is rotational kinetic energy equal to the moment of inertia of the system times the square of the magnitude of the angular velocity. Clearly the rotation of the entire airframe would contribute but also rotation of say, spinning turbines at high speed could also be a component. Rotation axes in different directions could lead to transfer of rotational energy between different modes. Apart from these contributions to total kinetic energy there is also some energy in vibration of massive components as well but likely to be numerically less significant. Of course there is stored energy in unburned fuel that can be released as well.

The various elements of kinetic as well as potential energy can then be dissipated into destructive rupture, distortion and other failure modes on impact (as well as a small amount to heat and sound). This is a physics perspective as a general consideration applying to any accident in the air.
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Old 9th Jan 2015, 18:18
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Daily Mail reports:

A director from the Indonesian search-and rescue agency said readings detected on Friday suggest the black box may be outside the tail section of the plane. It comes as footage has emerged showing Indonesian military divers investigating the submerged tail of doomed AirAsia flight 8501, as search and rescue teams are hopeful that the black box from the plane's wreckage has been located. Having located the tail of the plane on Thursday, search teams began pressing ahead with their efforts to find the black box and retrieve bodies from the wreckage, and on Friday afternoon reported detecting 'pings' from the flight data recorder.

But Suyadi Bambang Supriyadi, director of operations of Indonesia's search-and-rescue agency, said pings detected about 1km southwest of the wreckage suggest the black box may be located elsewhere, reports Business Spectator. Inside the wreckage: Divers search for AirAsia black box. The underwater searches ended before dusk on Friday, after divers were unable to find the black box Lifting balloons were loaded onto helicopters in preparation of recovery efforts to lift the tail out of the Java Sea, despite worries that the black box may have been separated from the tail during the crash.

Navy ships USS Sampson and USS Fort Worth have deployed helicopters and sonar devices into the Java Sea to aid the recovery operation off the coast of the Indonesian island of Borneo. Only 43 bodies have been retrieved so far, as monsoon rains and winds have caused choppy sea conditions and blinding silt from river run-off, reducing visibility underwater and preventing the removal of large pieces of the wreckage. Many of the other passengers are believed to be inside the wreckage of the plane's main cabin, which has not been located, due to strong currents moving debris around. At two weeks, most corpses will sink, said Anton Castilani, head of Indonesia's disaster identification victim unit, and there are already signs of serious decomposition.

'Divers have reached the tail part but ... the visibility was below one metre so they only managed to retrieve various debris,' said Bambang Soelistyo, chief of Indonesia's search and rescue agency. 'Now we are waiting for the speed of the current to ease. If it gets calmer later, they will go back to do another dive to determine whether the black boxes remained in the tail or were detached,' Mr Soelistyo said on Thursday. Divers travelled by rubber boat from the KRI Banda Aceh warship that was being stationed close to the site of tail wreckage, which Mr Soelistyo said would be lifted off the seabed by retrieval experts on Friday if weather permitted.

Lieutenant. Edy Tirtayasa, commander of Indonesia's navy rescue team, told Channel News Asia they planned to send two contingents to the plane. 'We are going to send down one observation team to take photos. Then two teams will do the recovery process -- to recover bodies if there are any,' he said.
[/B'If not, they will recover the black box for investigation and then other debris from the aircraft, he said.

[B]Coordinating Minister for Maritime Affairs Indroyono Soesilo told reporters the black box would be analysed by experts in Indonesia when it was located.
It will provide essential information about the plane along with final conversations between the captain and co-pilot, despite the Indonesian meteorological agency indicating that weather was the 'triggering factor' of the crash, with ice likely damaging the engines of the Airbus A320-200. Five other big objects have been found on the floor of the ocean, though no visual confirmation has been obtained yet. Smaller pieces of the plane, such as seats and an emergency door, have been collected from the surface.
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Old 9th Jan 2015, 18:28
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Is there a reason the hours of darkness are not used to search for the pingers?
It should be less noisy than during daytime and the lack of visibility is not a concern.
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Old 9th Jan 2015, 18:34
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Originally Posted by etudiant
Is there a reason the hours of darkness are not used to search for the pingers?
It should be less noisy than during daytime and the lack of visibility is not a concern.
For every guy in the water, there are several more topside who need decent visibility to properly support them.
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Old 9th Jan 2015, 19:02
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The pieces of the puzzle thus far are:

Convective wx.
Sudden loss of comms.
A number of bodies recovered, of which one of the first two was a flight attendant (possibly rear seat occupant)
Wide dispersed wreckage, of which empennage comprises a large section.
Short rapid climb preceeding loss of comms and ATC SSR/primary radar ident.

Displays hall marks of let`s get out of Dodge fast, in heavy clag and leaving the tail behind. The question is how do you make an A320 go ballistic.
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Old 9th Jan 2015, 19:27
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Originally Posted by Chronus
The question is how do you make an A320 go ballistic.
On take off, JATO booster rockets might be of help. (Meant as a joke. A320 airworthiness cert probably does not include JATO takeoffs.)

On high, the FDR when found may provide a few clues if that was what happened.
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Old 9th Jan 2015, 19:28
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Do we have any indication of the actual duration of the steep climb?
3 seconds vs 30 for example, quite a different kettle of fish.
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Old 9th Jan 2015, 19:30
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For every guy in the water, there are several more topside who need decent visibility to properly support them.


Absolutely, so the divers and support people should all be getting rest.
I'm thinking of having some of the ships that drag acoustic arrays work at night, they should be able to triangulate the pingers pretty well, if they are still running.
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Old 9th Jan 2015, 19:46
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I haven't read all this thread, but has anyone suggested a jet coming out of a CB's?

Red Sprites and Blue Jets
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Old 9th Jan 2015, 19:58
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Afaik, lightening of whatever type is not a significant threat to airplanes. The bolts travel through the outside of the metal body and the charge is leaked off through trailing wicks.


A terrorist device would be a much more likely explanation, imho.
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Old 9th Jan 2015, 20:22
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Toruk Macto
How hard would it to be to have a basic AOA indicator installed in every commercial jet ? Then a basic training package to be included in every endorsement that trains to react in a situation when all hell brakes lose ? Consider it a last resort recall ? They seem to be taking care of passengers with new lounges , upgraded on board entertainment and meals , but in the end passengers may go without if they knew money went to a instrument that could make a difference ? Just a thought
Airbus has AOA protections so having a dedicated AOA instrument is deemed less important by some people. This is a much argued controversy.
The stall warning is the most basic AOA indicator which is carefully designed to help prioritize attention. This topic was argued in depth on the AF447 thread.

BEA Report extract:
In alternate or direct law, the normal law high angle of attack protection is lost but the stall warning is available. It consists of a “STALL, STALL” aural warning, followed by a characteristic cricket sound and the illumination of the Master Warning light. It is triggered by the FWC when the highest of the valid angle of attack values exceeds the threshold set for the flight conditions at that time. If the CAS measurements for the three ADR are lower than 60 kt, the angle of attack values of the three ADR are invalid and the stall warning is then inoperative. This results from a logic stating that the airflow must be sufficient to ensure a valid measurement by the angle of attack sensors, especially to prevent spurious warnings.
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Old 9th Jan 2015, 20:39
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Originally Posted by Organfreak
Ian W sayeth,

Not asking argumentatively, and notwithstanding TV shows such as "CIS," would these doctors have any qualifications for judging such things?
warning not for the squeamish

They don't need "qualifications for judging such things". If the passengers recovered:
* show signs of drowning with water in the lungs etc. Then the impact was not sufficiently hard to kill the passengers.
* Show signs of explosive decompression with ruptured ear drums and associated signs of barotrauma it is possible the aircraft decompressed at high altitude
* have compression fractures and broken lower limbs etc. and no signs of drowning Then the impact was probably severe and the aircraft landed flat onto the surface of the water.
* have seatbelt bruising and associated inuries perhaps some with signs of submarining under the seatbelt, then the aircraft had significant forward velocity when it hit the surface.

etc etc. There are more but I don't think I should belabor the point.

Associate these simple observations with any deformation of the seats and airframe and you do not need a DFDR to show what the final seconds were.
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Old 9th Jan 2015, 20:57
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A number of posts earlier in this discussion have mentioned that an angle of attack instrument would help the pilots make a better assessment of a possible stall condition. I noted with interest that in the AF447 final report that is readily available on the web, in section 4.2.2 it says, "Information on angle of attack is not directly accessible to pilots", and a couple of lines later, "it is essential in order to ensure flight safety to reduce the angle of attack when a stall is imminent. Only a direct readout of the angle of attack could enable crews to rapidly identify the aerodynamic situation of the aeroplane and take the actions that may be required". That seems a clear enough recommendation concerning the A330.

The A330 aircraft type involved in the AF447 accident did have, as standard, angle of attack sensors installed, but may have become blocked in the weather conditions prevailing at the time of that accident.

Does any A320 pilot here know if the situation is similar on the A320 i.e. that AoA sensors are installed, and the data available to the flight control system but not as a direct readout that the pilots have access to? Or was the fitting of AoA sensors not part of the design of the A320?
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Old 9th Jan 2015, 21:25
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Originally Posted by etudiant
Absolutely, so the divers and support people should all be getting rest.
I'm thinking of having some of the ships that drag acoustic arrays work at night, they should be able to triangulate the pingers pretty well, if they are still running.
I'm sure that any ship operating in the area has their passive gear listening 24/7. Dragging the fish can be done in most weather conditions, sometimes it needs to come in for feeding and a nap. Depending on your gear it may be safer and more efficient to bring said fish aboard while daylight is on your side.
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Old 9th Jan 2015, 21:38
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No divers were involved in the retrieval of AF447 and its black boxes. Can the same technology not be employed in the Java Sea?
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