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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 24th Jan 2015, 13:33
  #2461 (permalink)  
 
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Thank you guys to remind me Archimedes principle. But I'm still not conviced. In AF447 case the fin was floating because it's an hollow object (mostly composite) "almost intact" and nothing was attached to it while in QZ8501 case there is quite an amount of structure attached. Also the rudder is partially ripped off, this don't help the floatation (water filling).
But maybe the proposed mapping is not quite accurate. Let's wait the official report.
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Old 24th Jan 2015, 13:39
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Trying to summarize

A majority impression (but certainly not the only scenario) seems to be a baseline scenario consisting of:

- the plane almost pancaked the water (final situation being either in stall, or spin, or upset recovery), but a bit wing left, and a bit nose up,

-- nose up, leading to the breaking away of the tail, and of heavy parts breaking away from their mountings and expelled from it, including the FDR and CVR,

-- left wing based on missing one wing, and fuselage apparently torn open on one side (I add this last one - have not read it before - but looks a bit like that on the UW photo), and would explain a number of seatrows being torn loose and floating away,

-- nose up leads to break away of the radome, which starts float of 500+ km, carried by an on average 0.65 knots estimated surface current,

-- tail and aft section segment break off, float initially, float over the fuselage location with the prevailing NW to SE current, get waterlogged, incrementally sinks to the bottom a few hundred meters further,

What this does not explain is:

- why are we still missing the cockpit section?
-- one poster says he has already seen it on the UW pictures,
-- the NLG is quite big and has a strong mount, miss that too,

- why are we still missing at least one engine
-- buried in mud or covered by fuselage and wing perhaps,

- why are we still missing the THS?
-- large piece with 12.45 m span,
-- but flat, and lying flat (otherwise SS-sonar might have spotted it) so maybe buried in mud??
-- maybe detached in whole or part at lower altitude?, ref situation, ref damage of THS on China Airines plane,
-- did it float ...?
-- at this stage THS is the part that I am most interested in, the cockpit being next ... both representatives of the four corners by the way. We are in fact still missing three corners!

- why are we still missing the APU ?
-- buried in mud perhaps, or its smaller size,
-- what has the search/sonar prio of the SAR been till now?

Would you agree that this is the majority view, not necessarily your own view, of the baseline scenario. If you disagree with it, what is the piece of evidence (based on what is found and published till now) that makes you disagree.

Last edited by A0283; 24th Jan 2015 at 14:01. Reason: Add seatrows.
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Old 24th Jan 2015, 13:49
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Stall Spin training: re-inventing the wheel

Folks are now re-inventing the wheel, i.e. noticing that many young, and not-so young, airline pilots must re-learn to hand-fly. Have many hangar-mates, some of whom are friends, who fly, or flew, for AF. Except for the few who are ex-fighter, aerobatic or airshow pilots, most are TERRIFIED of high high AoA, slow flight and stall and spins. Why... because they never explored the corners of the envelope in training. And still don't want to learn/go there. Not just FOs, but senior Captains. Ego?

Folks might do well to listen to Mr. Hoover's good ol' boy common sense about altitude, airspeed... and practice: https://www.youtube.com/watch?v=g7R7jZmliGc

And, from Chief Airbus test Pilot Claude Lelaie's recent book:

Altipresse

"The quality of a pilot’s basic instruction is fundamental. This is what “formats” pilots to have the proper reflexes, and to deal with difficult situations and or emergencies. Once a pilot obtains an Airline Transport Pilot licence, training is generally limited to the items specific to type rating on a given aircraft. A pilot will also follow specific modules, to become a captain, for example. But, in this case, it is no longer a handling issue, but a decision-making one.Without re-training, are the basic reflexes acquired during initial training still present thirty years after? Probably not. Military pilots who are used to flying in unusual attitudes (inverted, high bank angles, etc.) have no difficulties. The same applies to pilots also fly for fun in their time off, particularly if they do aerobatics, gliding, or mountain flying…the kind of flying that truly requires “hands-on” and “eyes-outside” the cockpit. But we must face the truth: the situation is different for those pilots who, after basic training, have only flown commercial flights for twenty or thirty years."

Last edited by formationdriver; 24th Jan 2015 at 22:12.
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Old 24th Jan 2015, 13:56
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Originally Posted by A0283
- why are we still missing the cockpit section?
-- one poster says he has already seen it on the UW pictures
Linked story above from Channel NewsAsia:

The rescue agency official also said a sonar scan had detected an object "suspected to be the cockpit" of the plane about 500 metres away from the fuselage.
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Old 24th Jan 2015, 14:05
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mcloked 24 jan re link

..The post link was copied from myn post - since it truncates the actual link- re china 747

use ...

China Airlines B747SP Loss of Power and Inflight Upset
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Old 24th Jan 2015, 14:07
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@thf - on cockpit

The rescue agency official also said a sonar scan had detected an object
"suspected to be the cockpit" of the plane about 500 metres away from the
fuselage.
There was also a report from an official that they had found the cockpit. And that divers had been tasked with recovering the pilots. But, ref its importance as one of the four corners and the pilots, I would have expected a much much stronger statement if they were sure. I still have it in my 'unconfirmed column'.


Ref the article in your post - The same news was published a few days ago, I think citing the same official. The wording is very careful. So, still unconfirmed. Which might be a bit surprising. The baseline scenario would make it quite probable that the whole cockpit section would snap off. Such a section would not be hard to find and identify?

My impression of the blackandwhite underwater photos is that the ROV sailed over the main fuselage from aft to front. The letters visible are on the righthand side of the plane. And would therefore rest on its left side. The last image stops short of the forward and cockpit section then. The 500 m difference would then be strange when you compare it to the baseline scenario. You could imagine some kind of weird flip and float scenario, but Mr Occam R would cut that short. Keep in mind, the water at the spot is 28-30 m deep only.


If the cockpit lies under the track and before the main. Then some kind of shallow angle nose first landing could be an option (breaking the nose of and the main slamming back down a fraction later). Depending on the angle you could imagine a Tau instead of a Sigma force (engineers will know) on the 'hinge' of the radome. Which might explain how it came off. So we need to know the location of the cockpit.

Last edited by A0283; 24th Jan 2015 at 14:59. Reason: Add comment on refd article content. Add tau/sigma.
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Old 24th Jan 2015, 16:08
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With great interest I read the various posts on stall, spin and (viewed the FAA video on which had clear definitions on upset and stall) upset recovery.

Now how can we use that knowledge to improve matching of available information?

When you take the last known part of the flightpath, it ends with a left-turning 360 spiral small diameter 'circle'. If you try to match that spiral with the baseline scenario in post #2480 and the debris field, then what would we see.

First, it appears that with 2-3 at minimum, of those small diameter 'circles', placed one after another with a little overlap, you get to the point of impact. To get on a final trajectory matching the debris field you need to complete full circles. This because the tangent of the trajectory needs to point in the direction of the debris field.

Second, the last know altitude is about 24,000 ft and the rate of descent is about 7,900 fpm. So roughly, 3 minutes to get down to the point of impact.

If we take 3 turns, then we get exactly 1 turn per minute as the fastest 'speed along the spiral track'. Based on the diameter of the 'circle', the 1 minute, and the descent rate of 7,900. We would then get a first estimate of the speed along the spiralling/corkscrew track.

Before trying to calculate that, I hope there are posters who can give their feedback on this respresentation. Feedback primairily on the pre-impact scenario.

How do you fly one such circle and at the same time descent 7,900 ft.

Last edited by A0283; 24th Jan 2015 at 16:14. Reason: Add example
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Old 24th Jan 2015, 16:41
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I think you are wasting your time trying to interpret some else's interpretation of what they imagined the flight path to look like based on some radar plots.

None of that can tell you the actual position or attitude of the aircraft at any point in time. They could have been inverted or had the nose pointed straight up or straight down in any of those plots.

It is only a short time before the FDR will reveal all there is to know. Why be so impatient?
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Old 24th Jan 2015, 18:43
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So far - and I may have missed it - all the discussion has postulated a sudden pitch-up on encountering an updraft. Running some numbers on my calculator, I see that an aircraft at 480 kts, entering a 100 kt updraft, would experience about a seven degree change in the relative wind (equivalent to a seven degree increase on AoA) without any attitude change at all. Presumably this would result in a sudden gain in altitude and loss in airspeed without much sensory input for the pilots.

Is this a reasonable scenario, and could it have been disorienting enough to have contributed to a loss of control?
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Old 24th Jan 2015, 18:51
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Originally Posted by A0283
...last known altitude is about 24,000 ft and the rate of descent is about 7,900 fpm. So roughly, 3 minutes to get down to the point of impact.
The data from which the flight path you are referring to has been constructed from an animated presentation originally prepared by the Indonesian Directorate of Civil Aviation for the Minister of Transport. A distorted grey-scale image later made its way into the media.

As originally constructed, each ADS-B or transponder position recorded was represented as a dot on the track. Some were missing, but overall they were updated every second. In the animation, the aircraft depicted moved along the track at the GS represented by its position, slowing quite dramatically shortly after commencing the left-hand climb.

Some of the data used initially would have been Baro, but it appears that Baro data was lost at some point in the climb and the later data was GEO only. This could indicate the transponder had detected conflict with the Air Data, and as in the case of AF447 had rejected it to prevent causing potential TCAS conflict problems.

The few points on the graphic that were notated with times, should not be used to calculate future or past conditions as they were affected by substantive rates of change. The appearance of a possible spiral turn at the last data point when passing through 24,000' (GEO) with a VS of -11,518 ft/min is unlikely to directly convert into what was happening at impact.
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Old 24th Jan 2015, 19:29
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Gentlemen
After reading these posts almost daily and very detailed they are.
I'm left with the thought as to the possible cause of the crash as;

Approaching a line of embedded CB's and requesting higher FL was cleared higher but denied deviation of track due traffic.
Climbed at an unbelievable rate of climb which possibly coincided with severe turbulence resulting in structural failure.
This was my initial thought as well, but the relatively tight debris field, photos of the main fuselage structure and the apparently intact and floating radome in fairly good condition would to me seem to indicate that this aircraft impacted fairly intact and more or less on its belly. Now, that said, I don't think the concept can be entirely discounted until more wreckage is recovered and studied. There are a lot of parts of the aircraft that have not yet been recovered, so I think it's premature to leap to any conclusion just yet.

By way of example, here's the wreckage distribution description from the accident report on the 1963 inflight breakup of a Boeing 720 near Miami that was discussed much earlier in this thread:

The main wreckage area was located in a section of the Everglades which was fairly open and flat, with outcroppings of coral rock, marshy water areas, and groves or hummocks of cypress trees irregularly spaced at one-half to one mile intervals. Access to the area from the nearest road, 15 miles away, required over three hours by surface transportation or 15 minutes by helicopter. The wreckage distribution was aligned 080-260 degrees, approximately 1-1/3 miles wide and 15 miles long, indicating in-flight breakup of the aircraft structure. Approximately 90 percent of the wreckage, including all large segments, was found in the most westerly two miles. The remaining portions of wreckage found east of this concentration consisted mainly of light material which was drifted to the east-northeast by the prevailing winds aloft. The most westerly piece of wreckage was the upper part of the rudder, which was used by surveyors as a zero datum point. Approximately 500 feet east of this point were engines Nos. 1, 2, 4, 3, in that order, oriented along a south to north line one-half mile long. Five hundred feet northeast of the No. 3 engine was the cockpit area. Next, approximately 1,500 feet east of the rudder fragment were the outboard portions of both wings Two thousand and seven hundred feet east of the datum point were the main fuselage and wing center sections which landed inverted on a heading of 060 degrees. The tail section was 1,000 feet farther east. Approximately 97 percent of the aircraft was recovered.
Full report here: DOT Online Database)

There are some similarities here in terms of distances between sections of the aircraft and the longer distances involved with Air Asia are easily explained by drift due to ocean currents.
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Old 24th Jan 2015, 20:29
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Some of the data used initially would have been Baro, but it appears that Baro data was lost at some point in the climb and the later data was GEO only. This could indicate the transponder had detected conflict with the Air Data, and as in the case of AF447 had rejected it to prevent causing potential TCAS conflict problems.
I am not familiar with the Airbus implementation of ADS-B or Mode S input/output. Is there logic that will decide which altitude to discard -- ADC or GPS/IRU? Is the logic part of the ADS or Mode S spec, or are implementations different between mfgrs and fleets?
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Old 24th Jan 2015, 22:23
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I am not familiar with the Airbus implementation of ADS-B or Mode S input/output.
The Mode S came up in the AF447 Reports, and from memory the Xpndr was Honeywell. Whether the ADS-B was also affected, I'm not sure.
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Old 24th Jan 2015, 23:23
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Basics

I have been more than a little concerned for many years now we are getting away from the basics in stick and rudder skills. For example i came across an advertisement recently for a Piper cub pilot but the candidate needed a collage degree to be eligible to apply for this position. Can anyone here inform me WTF a college degree has anything to do with stick and rudder skills?? I have known young people who were natural pilots and never had to think about control inputs for example. They were able to do it naturally. Now these people I know for a fact have been over looked because of lack of "academic achievement". This is part of the problem we are facing today with the basics.

Now DA with the avionics they use "easy" I think it's termed, require a whole new type rating for an "easy" avionics fit. Where, God give me strength, is the simplicity in that?? Sorry but i call BS on this. We seem not to be flying the air frame anymore, but the automatics. This does and has scared me for a long time now. WTF ever happened to K.I.S.S?
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Old 24th Jan 2015, 23:50
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Current effect

One's mind keeps returning to how wind and current would affect the parts found so far apart.

Given that the recorders appear to have been dislodged at impact and that they are amongst the densest parts, one would surmise that they sank very near the actual point of impact. Downstream drifting of the rudder and fin is not surprising given their residual buoyancy and I shouldn't be surprised if the elevators wash up on a beach, with or without the apu, near where the nose cone was found.

What I do find surprising, though, is that the recorders were both found "under a wing" which, if the premise of their sinking first is correct, would indicate that part of the wing and main fuselage also sank very rapidly. Perhaps, if still attached to the wing box, dragged down by the weight of the main undercarriage?

The puzzling thing is the cockpit/forward fuselage. Little buoyancy, weighted down by the nose gear and electronic bays, would it not also sink like a stone? And, if so, one'd expect it to be near the main fuselage. I wonder if it's not folded underneath.
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Old 25th Jan 2015, 00:27
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The puzzling thing is the cockpit/forward fuselage. Little buoyancy, weighted down by the nose gear and electronic bays, would it not also sink like a stone? And, if so, one'd expect it to be near the main fuselage. I wonder if it's not folded underneath.
Unlikely, it would have been spotted when they raised the fuselage.
(And then dropped it when a rope broke.)
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Old 25th Jan 2015, 03:07
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sop monkey

I've never met anyone who was a ''natural pilot''. I've been called a natural pilot by some and I told them I had to study everything twice as much as most. I think the term , ''natural pilot" is wrong to ever use.

College shows that you can train your mind, learn how to learn. And most airline pilots will tell you that stick and rudder skills are not tested on the Oral exam. ;-)

I've known very good pilots who didn't finish college. And I've known some rotten ones with degrees.
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Old 25th Jan 2015, 03:29
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The black boxes were obviously found some hundred feet away from the main wreckage. But they were said to be stuck under a "wing" and tangled in other wreckage remains.
Probably the divers misstake the horisontal stabiliser for the wing, so the rest of the rear assembly including the quite heavy APU can be on the spot where the boxes were found.
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Old 25th Jan 2015, 05:09
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So far - and I may have missed it - all the discussion has postulated a sudden pitch-up on encountering an updraft. Running some numbers on my calculator, I see that an aircraft at 480 kts, entering a 100 kt updraft, would experience about a seven degree change in the relative wind (equivalent to a seven degree increase on AoA) without any attitude change at all. Presumably this would result in a sudden gain in altitude and loss in airspeed without much sensory input for the pilots.

Is this a reasonable scenario, and could it have been disorienting enough to have contributed to a loss of control?
You have missed it.

Some discussion has postulated a sudden pitch-up on encountering an updraft.

These postulations have been time and time discredited by those who actually understand what happens when entering an updraft - ie the aircraft will pitch DOWN not up and the airspeed will INCREASE not decrease.

Any glider pilot will tell you have to try pretty hard to lose airspeed in an updraft.

The only thing that will result in a sudden gain in altitude and loss in airspeed is a zoom climb, which is caused by the aircraft pitching significantly upwards, as happened to AF447, and as also appears to have happened here.

What we don't know here is whether the significant pitch up was caused by a pilot pulling back on the stick, a mechanical malfunction, a sensor malfunction, or whatever else. Presumably the FDR data will tell us in time. But can we quit with all the updraft speculation please?
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Old 25th Jan 2015, 06:01
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Totally agree.
Another side to this is if you are on ILS to RW25 at LAX you will traverse the duty thermal over the car park on short finals. Because you need to maintain a constant G/S, then the extra energy from the thermal means that you gain 5-10kts unless you reduce thrust (in a heavy).

We simply don't know why the pitch up occurred or why it turned left.
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