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EK413
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Air Asia QZ8501 SUB To SIN Crash - Part 13

Fri Jan 23, 2015 11:28 pm

Hi All,

Due to the length of the previous thread please continue your discussions here.

Part 12 can be found here: Air Asia QZ8501 SUB To SIN Crash - Part 12 (by American 767 Jan 19 2015 in Civil Aviation)

May all the victims of QZ8501 Rest in Peace

EK413
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 12:12 am

Any chance of having a "facts that we know so far" message at the top of these threads, so one doesn't have to wade through a dozen pages of speculation and arguing to get up to speed, while also possibly cutting down on the amount of duplicate information being posted (which further drives up post counts and the need for new threads)?
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BestWestern
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 12:18 am

Going back to my very first question in the very first thread

Why was there an engineer on board?

Was the airline checking the equipment swaps and placed an engineer on-board to monitor?

Just to be clear - I do not believe that Air Asia would have flown an aircraft they knew to be in danger. I think that what happened was an accident.
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Kaiarahi
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 12:43 am

Quoting bestwestern (Reply 2):

Why was there an engineer on board?

Was the airline checking the equipment swaps and placed an engineer on-board to monitor?

According to the seat map in an earlier thread, he wasn't jump-seating, which would suggest he wasn't monitoring. Just heading to SIN for any number of reasons.
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32andBelow
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 12:46 am

Quoting bestwestern (Reply 2):

Going back to my very first question in the very first thread

Why was there an engineer on board?

Airlines just move people around their system as they need to. It happens all over the world every single day.
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 1:39 am

The aircraft was supposed to be doing SUBSINSRGSINSUB.
As far as I remember SRG is new to Indonesia Air Asia network, and they no engineers at that base that is approved by the DGCA to work on their A320s, nor 3rd party engineers that were already approved, hence they carry an engineer on that flight, so if there is a MEL-able snag, they can still have the flight released.
This is typical for airlines in Indonesia.

I had cross checked with someone with the airline regarding the maintenance write ups.
They could not replicate the problems the pilots wrote on the ground, none of the ground test procedures produced the same errors. But since ELAC1 and FAC2 reported faults in the air, they were replaced. The FAC2 came from another aircraft (but was checked for version and other applicability). The post replacement checks and flghts revealed none of the previously reported issues, and no new issues.
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 1:51 am

Quoting HOmSaR (Reply 1):
Any chance of having a "facts that we know so far" message at the top of these threads, so one doesn't have to wade through a dozen pages of speculation and arguing to get up to speed, while also possibly cutting down on the amount of duplicate information being posted (which further drives up post counts and the need for new threads)?

Good idea  
Quoting bestwestern (Reply 2):
Why was there an engineer on board?
Quoting mandala499 (Reply 5):
The aircraft was supposed to be doing SUBSINSRGSINSUB.
As far as I remember SRG is new to Indonesia Air Asia network, and they no engineers at that base that is approved by the DGCA to work on their A320s, nor 3rd party engineers that were already approved, hence they carry an engineer on that flight, so if there is a MEL-able snag, they can still have the flight released.
This is typical for airlines in Indonesia.

Thanks for that info regarding the engineer being on board. That makes sense.

Is there always or usually an engineer on that specific flight for the reasons you mentioned?
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 2:04 am

Quoting maxpower1954 (Reply 308):
"The A320 does have mechanical back up control of the rudder, but it's not manual reversion in the conventional sense. In case of total electrical failure, the cables move the hydraulic actuators instead of the FBW servos. You still need hydraulics to move the rudder. "


Thanks, I suspected it was sort of a combination.

Pihero, believe me, I didn't trust the NYT on the subject!  
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 2:42 am

So the manual backup is only for the electrical system that sends commands to the rudder hydraulic actuators? In other words to replace the electric command path with a mechanical one?

Lose all three hydraulic systems and it's basically SOL? I'm not sure if that's a good thing really.   

Give me cable-driven tab operated surfaces ... thank you. "Insert Luddite smiley here"
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 4:14 am

Quoting md80fanatic (Reply 8):
So the manual backup is only for the electrical system that sends commands to the rudder hydraulic actuators? In other words to replace the electric command path with a mechanical one?

Lose all three hydraulic systems and it's basically SOL? I'm not sure if that's a good thing really.   

Give me cable-driven tab operated surfaces ... thank you. "Insert Luddite smiley here"

You are 45 years too late!

Aircraft that have no mechanical backup system for total loss of all hydraulic systems - 747, DC-10, MD-11, L-1011, 757, 767, 777, 787, A320 series, A330, A380, A350. And I believe the CRJ-700/900 from what I understand. I'm sure I missed some.
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 4:34 am

Quoting maxpower1954 (Reply 9):
Aircraft that have no mechanical backup system for total loss of all hydraulic systems - 747, DC-10, MD-11, L-1011, 757, 767, 777, 787, A320 series, A330, A380, A350. And I believe the CRJ-700/900 from what I understand. I'm sure I missed some.

... and the last cable-driven-tab-operating-surfaces jet was the DC-9/MD80;90/B717 which was the only jetliner I detested at first contact : imprecise, slow and late handling ( still in the zig when zag was required ). Hell to fly with a modern - for that time- flight director... a bitch... A 741 had crisper controls and that's saying something.

On the other hand, modern flight control architecture allows control with a total hydraulic system failure. See the A380 as a model.

But I digress.

Apologies.
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md80fanatic
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 4:48 am

I cannot speak against my favorite airliner.   

Everything is a tradeoff in this world, for one extra layer of security the cost is a bit of control throw "lag". A price I would pay if a pilot, and a safety feature I would pay double for as a passenger.
 
md80fanatic
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 4:53 am

Quoting maxpower1954 (Reply 9):
Aircraft that have no mechanical backup system for total loss of all hydraulic systems - 747, DC-10, MD-11, L-1011, 757, 767, 777, 787, A320 series, A330, A380, A350. And I believe the CRJ-700/900 from what I understand. I'm sure I missed some.

Of all those ... only one have I ever been on before, and that was an A320.
.
.
.
Didn't like it. (got bumped from an MD and ended up in an Airbus so was a little upset anyway)

I'm surprised the large Douglas birds didn't have such a system, that was a departure from tradition (and a signal of the end of the company IMHO)
 
32andBelow
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 4:55 am

Quoting md80fanatic (Reply 12):
I'm surprised the large Douglas birds didn't have such a system, that was a departure from tradition (and a signal of the end of the company IMHO)

That list includes almost every single aircraft type that was designed after X date.
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 4:59 am

"Modern" and "Progressive" are words that don't always mean "better".  
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 5:01 am

Quoting md80fanatic (Reply 8):
So the manual backup is only for the electrical system that sends commands to the rudder hydraulic actuators? In other words to replace the electric command path with a mechanical one?

Lose all three hydraulic systems and it's basically SOL? I'm not sure if that's a good thing really.   

Give me cable-driven tab operated surfaces ... thank you. "Insert Luddite smiley here"
Quoting md80fanatic (Reply 11):
Everything is a tradeoff in this world, for one extra layer of security the cost is a bit of control throw "lag". A price I would pay if a pilot, and a safety feature I would pay double for as a passenger.

There isn't any deterioration in safety compared to a cable system since the manufacturer has to demonstrate the same reliability and fault tolerance regardless of the system.
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md80fanatic
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 5:03 am

A very interesting plot was posted to the other site a moment ago ...

 
32andBelow
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 5:05 am

Quoting md80fanatic (Reply 14):

"Modern" and "Progressive" are words that don't always mean "better".  

Are you saying that there are more accidents with current systems over former systems? Because that certainly is not true.
 
LTC8K6
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 5:05 am

http://pbs.twimg.com/media/B8E3NRsCIAEfL_y.png:large

Debris field added to blue plot chart.

Don't really know the source, though.

[Edited 2015-01-23 21:24:45]
 
bellancacf
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 5:17 am

The left turn seems to have preceded the climb. Did we know that? The initial left turn, then, wasn't the result of the sharp climb. The simplest assumption would be that it was commanded, I guess.
 
md80fanatic
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 5:19 am

Quoting 32andBelow (Reply 17):
Are you saying that there are more accidents with current systems over former systems? Because that certainly is not true

I didn't say "never", I said "not always" better.  

Anyway ... in that plot I see the FDR was found nearly 1/2 mile from the fuselage section and nearly 1.5 miles from the tail section. We were told that at least one recorder unit was found under the fuselage section wreckage. Since the CVR and the DFDR are mounted to a singular framework, which is TIG welded to the fuselage stringers beyond the aft bulkhead, it seems rather unusual to find the boxes 1/2 mile apart, knowing these pre-crash conditions.



I can't see how the DFDR could get to a position 1/2 nm south of the fuselage. The currents in that area are clear and not really variable, as being dictated by global ocean currents ... and the local current runs along a line between the "fuselage" and the "seats" marked on that plot. I doubt a crash like this could fling the DFDR 1/2 nm away, so how'd it get there?

[Edited 2015-01-23 21:28:33]
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 5:30 am

Quoting md80fanatic (Reply 20):
it seems rather unusual to find the boxes 1/2 mile apart

IIRC, the FDR position is well known, with coordinates, but the CVR position seems murky.
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 5:33 am

"The cockpit voice recorder, which retains the last two hours of conversation between the pilots and with air traffic controllers, was found close to where the flight data recorder was recovered from the bottom of the Java Sea on Monday."

http://news.yahoo.com/divers-retriev...irasia-jet-012421439--finance.html
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 5:38 am

Quoting md80fanatic (Reply 20):
so how'd it get there?

There was an airplane crash that ripped the plane to shreds?   How did any piece get far away from any other piece that was right next to it?

Is this just another conspiracy like the dented black box corner from Part 10 or the AA191 #3 engine flying off due to "physics?" It's hard to tell due to past posts suggesting such crazy things.

The level of discussion in these accident threads is getting pretty bad
 
md80fanatic
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 5:42 am

It seems that the location of these has "changed" since they were actually reported found. The divers who located them, and the pinger-locators that heard them, were all reported to be in and around the fuselage section at the time. The existence of a debris field located 1/2 mile south of the fuselage was not reported on at the time these boxes were found, IIRC.

With that "update" now known ... how can a reportedly intact aircraft deposit data recorders 1/2 mile south, which is almost 70 degrees off the direction of the local current?
 
md80fanatic
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 5:46 am

Quoting DeltaMD90 (Reply 23):
There was an airplane crash that ripped the plane to shreds?   How did any piece get far away from any other piece that was right next to it?

Are you suggesting that somehow these boxes floated there, against the current? Also, the plane wasn't ripped to shreds, there's 100 ft. section of upper fuselage skin sitting down there with the wing still attached.
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 5:52 am

Quoting md80fanatic (Reply 24):
It seems that the location of these has "changed" since they were actually reported found. The divers who located them, and the pinger-locators that heard them, were all reported to be in and around the fuselage section at the time. The existence of a debris field located 1/2 mile south of the fuselage was not reported on at the time these boxes were found, IIRC.

That makes no sense at all.

IIRC, the location of the fuselage was not yet known when the FDR was recovered.

"The FDR was retrieved early this morning local time from the floor of the Java Sea about 3000 metres from where the tail section was brought to the surface on Saturday."

"Indonesian authorities have confirmed that separate acoustic pings are being emitted from the CVR from an area believed to be a short distance from the FDR."

http://blogs.crikey.com.au/planetalk...potential-answers-to-many-riddles/
 
md80fanatic
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 5:52 am

Quoting DeltaMD90 (Reply 23):
Is this just another conspiracy like the dented black box corner from Part 10 or the AA191 #3 engine flying off due to "physics?" It's hard to tell due to past posts suggesting such crazy things.

Agenda alert!!!!  

I never claimed number 3 detached, didn't even allude to the possibility. You know there aren't many photographic records of pylons under strain/deformation ... that was one of the very few. That's why I chose that accident as evidence to support my claim that g's administered laterally -can- strain a pylon, and enough g's laterally can take a pylon to the breaking limit.
 
md80fanatic
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 5:56 am

Quoting LTC8K6 (Reply 26):
IIRC, the location of the fuselage was not yet known when the FDR was recovered.

With all due respect ... you aren't remembering correctly.

Anyhoo, without going too far off the deep end about conspiracies and crap ... let's get back to my original question. How'd the DFDR get to be 1/2 mile south of the fuselage, and 1.5 miles NW of the tail section, if the plane was intact when it hit the water?

[Edited 2015-01-23 21:59:55]

[Edited 2015-01-23 22:01:31]
 
LTC8K6
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 6:00 am

"He said the voice recorder was about 20 meters (66 feet) from the data recorder but remained lodged beneath heavy wreckage, and divers were struggling to free it at a depth of 32 meters (105 feet)."

http://wtnh.com/2015/01/12/divers-fi...-airasia-crash-retrieve-1-of-them/
 
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 6:02 am

Quoting md80fanatic (Reply 28):
Anyhoo, without going too far off the deep end about conspiracies and crap ... let's get back to my original question. How'd the DFDR get to be 1/2 mile south of the fuselage, and 1.5 miles WNW of the tail section, if the plane was intact when it hit the water?

What is the source/accuracy of the plotted locations?
 
md80fanatic
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 6:03 am

Okay, now we are getting somewhere. What heavy wreckage was this? If the recorders were under it, the wreckage above had to be part of the aircraft. Why no reportage of such a massive part?
 
Pihero
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 6:04 am

Quoting md80fanatic (Reply 16):
A very interesting plot

And there comes the "pretty picture" syndrome, once again !

As the last data published stopped at 24 000 ft and that we have no idea of the final heading and speed that picture isn't probably worth the ink one would spend printing it.
*Debris field* in all intellectual honesty should only relate to pin-pointed and localized sea bed resting positions. To include drifting pieces is taking the idea very far.

Quoting md80fanatic (Reply 20):
The currents in that area are clear and not really variable, as being dictated by global ocean currents ...

That's rubbish. With all the islands around, local effects of sea-tides, effects of water / land temperatures / estuaries... you cannot rely on a current general circulation on such a small area.

Quoting bellancacf (Reply 19):
The left turn seems to have preceded the climb.

Yes, apparently from the ADS-B read outs.

Quoting bellancacf (Reply 19):
The initial left turn, then, wasn't the result of the sharp climb.

Yes, you can make that assumption ( as I do )

Quoting bellancacf (Reply 19):
The simplest assumption would be that it was commanded, I guess

Unfortunately no. We don't know.
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 6:05 am

Indonesian salvage teams launch operation to raise fuselage of Flight 8501 from sea floor as they recovered 4 more bodies from wreckage, official says.
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LTC8K6
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 6:06 am

Divers did not reach the fuselage for the first time until Jan 23rd.

That is well after both recorders were already retrieved.


"PANGKALAN BUN, Indonesia: Indonesian divers on Friday (Jan 23) finally reached the fuselage of an AirAsia plane that crashed last month, an official said, as four more bodies were recovered from the Java Sea."

http://www.channelnewsasia.com/news/...8501-divers-find-more/1611064.html
 
CO953
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 6:07 am

Quoting LTC8K6 (Reply 18):
Debris field added to blue plot chart.

Don't really know the source, though.

What's missing from that debris-field chart, (although without a source, who knows about the accuracy) is the location of the cockpit.
 
LTC8K6
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 6:09 am

Quoting md80fanatic (Reply 31):
Okay, now we are getting somewhere. What heavy wreckage was this? If the recorders were under it, the wreckage above had to be part of the aircraft. Why no reportage of such a massive part?

It was described as "part of a wing" in several articles, IIRC, but may have been the H-stab, which looks a bit like a wing.
 
Tunasa
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 6:11 am

Quoting LTC8K6 (Reply 22):

"The cockpit voice recorder, which retains the last two hours of conversation between the pilots and with air traffic controllers, was found close to where the flight data recorder was recovered from the bottom of the Java Sea on Monday."

That was old news from last week? Both of FDR and CVR are with Indonesia's NTSC, they have downloaded the data if I am not mistaken.

Today they are trying to retrieve the fuselage.

http://www.straitstimes.com/news/asi...arch-teams-attempting-raise-fusela
Though the saying might be bitter, the truth is always beautiful.
 
LTC8K6
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 6:13 am

Quoting CO953 (Reply 35):
What's missing from that debris-field chart, (although without a source, who knows about the accuracy) is the location of the cockpit.

They mentioned finding the cockpit on sonar I think, but they were not sure it was actually the cockpit. 500 meters from the fuselage and stuck in the mud.

We have no direction, though.

"Earlier on Friday, chief of operation of the agency, Suryadi Bambang Supriyadi said the wreckage that appears to be the cockpit was located by sonar imagery about 500 meters from the fuselage and partly embedded in the mud."

http://www.news.com.au/travel/travel...ngine/story-fnizu68q-1227187788707
 
md80fanatic
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 6:16 am

Quoting Pihero (Reply 32):
That's rubbish. With all the islands around, local effects of sea-tides, effects of water / land temperatures / estuaries... you cannot rely on a current general circulation on such a small area.


Your a man of the air, a much less dense, and compressible, liquid. I'm speaking of bottom currents, BTW. Ocean bottom currents don't just change like the wind, or by the hour, day, or even month. Huge changes are seasonal, or even annual. It takes too much energy to change the direction and speed of a huge mass of water, in a relatively short time frame.

If quickly changing and unpredictable currents existed in the Java Sea, there would be mention of it on diving sites. This being a quite notable WWII shipwreck diving area ... would hate to set off for a 45 mile boat ride to the dive position, just to discover that bottom currents of 3 knots were happening that day.
 
LTC8K6
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 6:17 am

Quoting Tunasa (Reply 37):
That was old news from last week?

Of course it is old. It counters the above claim in #20 that the recorders were found 1/2 mile apart.
 
md80fanatic
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 6:22 am

Looking at the distance legend on that chart, which is 1 nm .... the line segment between the FDR and the fuselage is very close to half that length. In my geometry experience that would make the distance portrayed as 1/2 nm.

If anyone can refute that claim in post #20, using the given legend ... I'd like to hear it.
 
LTC8K6
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 6:30 am

Quoting md80fanatic (Reply 41):
Looking at the distance legend on that chart, which is 1 nm .... the line segment between the FDR and the fuselage is very close to half that length. In my geometry experience that would make the distance portrayed as 1/2 nm.

If anyone can refute that claim in post #20, using the given legend ... I'd like to hear it.

You are confabulating two arguments. First you said the recorders were 1/2 mile apart.

Then you switched to the recorders being 1/2 mile from the fuselage.

The recorders were close together, but not near the fuselage.

Why would they be near the fuselage?

I wouldn't expect them to be near the fuselage.

I would ask why they aren't near the tail.

You certainly have, by now, looked up the location of the recorders within the A320.

One wonders why you think they should be with the fuselage?
 
CO953
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RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 6:33 am

Please forgive me for an uneducated question here. I don't know enough to frame it very precisely: In the area of the Java Sea where the wreckage is located, and hypothetically assuming that the aircraft maintained electrical power almost all the way down the water, what is the lowest altitude that its presence should/could have been detected, given the detection capabilities in the area and the plane's various systems? And how long before there should have been another reported position, given the reporting gap/lag?

The reason I ask is that I'm trying to envision, using the "pretty picture" graph above, how many more turns, maneuvers, etc. the pilot may have had the opportunity to execute after that last position, and if they would have all had to have been in the same leftward direction to make the tail be southeast of the fuselage by that much. UA 232 was stuck mostly looping to the right, but the deadhead pilot assisting was able to make at least one big left turn in the other direction while trying to get lined up with the runway, using asymmetrical thrust.

UA 232 flight path here:

http://siouxcityjournal.com/flight-f...3-c673-5b60-a284-b0edd331c60c.html

[Edited 2015-01-23 22:35:36]

[Edited 2015-01-23 22:42:04]
 
LTC8K6
Posts: 1587
Joined: Fri Jun 05, 2009 8:36 pm

RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 6:49 am

Quoting CO953 (Reply 43):
what is the lowest altitude that its presence should/could have been detected, given the detection capabilities in the area and the plane's various systems?

IIRC, someone around here checked, and FL240 seems about right for the lowest point of detection for the Pontianak radar, ~200nm away?

What was left of the tail could easily have drifted before sinking.

[Edited 2015-01-23 22:49:51]
 
Backseater
Posts: 478
Joined: Fri Aug 19, 2005 3:20 pm

RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 7:26 am

Quoting LTC8K6 (Reply 44):
IIRC, someone around here checked, and FL240 seems about right for the lowest point of detection for the Pontianak radar, ~200nm away?

The early "gray" plot you provided shows a high density of data points (better than 1 per second). Therefore, their source is likely to be an ADS-B receiver with a fixed antenna, not a SSR radar with a rotating antenna.

So to determine the lowest visible altitude the question becomes: where was the closest operational ADS-B receiver of the surveillance network at the time?
 
mandala499
Posts: 6593
Joined: Wed Aug 29, 2001 8:47 pm

RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 7:42 am

From the previous part...

Quoting LTC8K6 (Reply 194):
Here is another plot posted on pprune with more info. Can't vouch for it's accuracy, but it seems to basically match what is leaking out.

I can vouch for the accuracy of this one. This one is based on the original ADS-B plot but using different snapshots for various points of interest in the trajectory, mainly when the turn started, maximum climb rate detected, nearest snapshot to peak altitude, the maximum descent rate, and when the barometer altitude was last detected, and points within the tight last circle to give a better timescale and understanding.

The one "officially leaked" by the minister (which in turn, broke the law in doing so), has different snapshots and less useful in my opinion.

Quoting 777Jet (Reply 6):
Is there always or usually an engineer on that specific flight for the reasons you mentioned?

They have engineers in SIN that are authorized to do work on QZ aircraft, but they are not allowed to work on QZ aircraft in Indonesian territory, hence they carry engineers on this one when there is the SIN-SRG-SIN tag-on.

Excuse my far and between replies... the airline industry in Indonesia is now under attack by the minister, who seems to want to turn the industry back to the stone age... Slightly out of topic...
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
Backseater
Posts: 478
Joined: Fri Aug 19, 2005 3:20 pm

RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 9:10 am

Quoting mandala499 (Reply 46):
I can vouch for the accuracy of this one.

Does that mean that you actually have the raw ADS-B data?

Quoting mandala499 (Reply 46):
when the barometer altitude was last detected

Does that mean no baro altitude after 23:18:45? So the FL240 shown on other plots at 23:19:46 was indeed spurious?

Furthermore, was there a GPS/IRS alt with every data point in the last 3 minutes of flight? Or were there flight segments "with" GPS/IRS altitudes alternating with flight segments "without"?

Finally, was there a GPS/IRS alt at 23:19:46 (probably around 14,000ft)?
 
Pihero
Posts: 4318
Joined: Mon Jan 31, 2005 5:11 am

RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 9:15 am

Quoting md80fanatic (Reply 39):
Your a man of the air, a much less dense, and compressible, liquid. I'm speaking of bottom currents, BTW. Ocean bottom currents don't just change like the wind, or by the hour, day, or even month. Huge changes are seasonal, or even annual. It takes too much energy to change the direction and speed of a huge mass of water, in a relatively short time frame.

I am also a PADI advanced diver and I'm quite familiar with local changes in currents speed and orientation in a given spot
How then do you explain the changing currents going from ~zero to a whopping 5 kt ( speed that prevented divers from working on the fuselage ) in matter of hours?

Secondly, the lat / long squares are 2 minutes apart. At a latitude of 3.5° South, these squares represent 1.996 nm per side.
So the scale is dead wrong... But I agree it's a very pretty picture, but I'd not use it for anything but toilet paper.
Contrail designer
 
Pihero
Posts: 4318
Joined: Mon Jan 31, 2005 5:11 am

RE: Air Asia QZ8501 SUB To SIN Crash - Part 13

Sat Jan 24, 2015 10:13 am

Quoting BackSeater (Reply 47):
Finally, was there a GPS/IRS alt at 23:19:46

If you looked at the trajectory, the difference between GEO altitude and FL is just about 2000 ft, consistent with a STD +20° temperature spread.
The last braodcast GEO Alt is 24 025 ft for an FL 235, and disappeared, meaning that somehow the IRS output was interrupted... reason unknown... Mandala499 posted that long time ago.
Contrail designer

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