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# Air Asia Indonesia Lost Contact from Surabaya to Singapore

Rumours & News Reporting Points that may affect our jobs or lives as professional pilots. Also, items that may be of interest to professional pilots.

# Air Asia Indonesia Lost Contact from Surabaya to Singapore

6th Jan 2015, 23:28

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23:10:54 4.091 s 110.344 e
23:10:57 4.083 s 110.335 e 3 sec 4700 940 kts
23:11:00 4.079 s 110.330 e 7 sec 2503 214
23:11:04 4.075 s 110.325 e 6 sec 2493 249
Calculating the speed based on adjacent ADS-B data points will not work. The data is just not precise enough to do this. Suppose that second data point was actually received at 23:11:00.999. If it had been received a thousandth of a second later then it would be timestamped a second later and the first delta t would have been 4 seconds instead of 3 and the second would be 3 seconds instead of 4. That would change the caclulated speeds by about 1/3, which is a couple of hundred knots.

A similar but smaller problem comes from the precision in the coordinates. If the delta in the latitude is .004 in one 3 second interval and .005 in the next, that does not mean the speed changed by 25%.
7th Jan 2015, 00:15

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Propduffer, you have not got enough significant figures in either the times or coordinates to make the speed assumptions you have given (remember you are calculation movement across the globe from these figures, not straight knots). In addition you have assumed a linear path in two dimensions. There is no way your figures are near correct.
7th Jan 2015, 00:18

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Well,sounds like too many people are buying airplanes that they are unable to operate as they were intended to. The proverbial "fourth floor" seldom knows what is done in third. And Fifth,usually believes the numbers given to them. First and second floor are trying to operate gadgets given to them. and in many cases,i would name elevator buttons from "4" upwards,perhaps,"notoriously known,so do not enter as a Friend."
7th Jan 2015, 00:19

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Strait Times report: Transportation Ministry suspended 7 over unscheduled flight

Indonesia has suspended seven officials over their suspected links to unscheduled flight approvals, which may include allowing Indonesia AirAsia to fly the QZ8501 Surabaya-Singapore route on Sundays, for which the airline has no permit.

Upping the ante yesterday, the Transport Ministry said it would work with the Corruption Eradication Commission (KPK) to get to the bottom of the matter.

"We will also support if the KPK is involved in the investigation into time-slot transactions," Transport Minister Ignasius Jonan told reporters.

The seven included two from the Transport Ministry, two from Surabaya's international airport operator PT Angkasa Pura I, and three from state navigation operator AirNav Indonesia.

The officials have been "deactivated", said Transport Ministry special staff member Hadi Djuraid. He did not say if the seven officials were involved in helping Indonesia AirAsia flout its route permit, which allows flights only on Mondays, Tuesdays, Thursdays and Saturdays.

AirNav Indonesia, however, has denied that its officials have taken bribes to allow airlines to alter their flight schedule.

There is no big money involved, and "if there is, we will act", its safety and standard director, Mr Wisnu Darjono, was quoted as saying yesterday.

"They are clean," he added, referring to the organisation and its air traffic control personnel. "Look at their dull faces. Not possible for them to have lots of money."

Angkasa Pura general manager Trikora Hardjo similarly denied any wrongdoing. "I will prove that Juanda Airport has not received even 1 per cent," he was quoted as saying, referring to the airport in Surabaya. "I am very sad when my child asked me, 'Papa, how much did you receive?' "

Mr Jonan yesterday said Air- Asia boss Tony Fernandes "admitted AirAsia has no route permit" and accepted the decision to suspend the QZ8501 route.

In the Java Sea, recovery teams had another difficult day yesterday, retrieving only two more bodies to bring the total to 39 so far, and were unable to locate the all-important black box.

Speaking in Pangkalan Bun, the commander of Indonesia's armed forces, General Moeldoko, said he saw for himself how difficult conditions were at sea after his inspection of the area. He again offered to help families of the victims to visit the crash site any day to scatter flowers and view search operations.
7th Jan 2015, 00:36

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Calculating the speed based on adjacent ADS-B data points will not work. The data is just not precise enough to do this. Suppose that second data point was actually received at 23:11:00.999. If it had been received a thousandth of a second later then it would be timestamped a second later and the first delta t would have been 4 seconds instead of 3 and the second would be 3 seconds instead of 4. That would change the caclulated speeds by about 1/3, which is a couple of hundred knots.
This is true, as I have found out - we can't get valid data between individual ADS-B data points. But if we had a hundred or so of them we should be able to deduce the effective winds aloft component by comparing reported TAS vs calculated groundspeed.
I suppose the data exists in the FR24 database, but that would be a lot of work for a pretty small return of information, unless it's already automated in FR-24's software.
A similar but smaller problem comes from the precision in the coordinates. If the delta in the latitude is .004 in one 3 second interval and .005 in the next, that does not mean the speed changed by 25%.
The difference between 4.091 s 110.345 e and 4.091 s 110.344 e is only about 400 feet or .07 nm and when (in this case) measured from the last data point it only makes a 209 foot difference in distance traveled (4,700ft vs 4,909ft) or about .5%.

Edit:
As Phalanger points out, this has to depend on an assumption of constant altitude.
7th Jan 2015, 01:33

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Note that the Flightradar24 data we are being shown above are from the actual ADS-B outputs from the plane.

The times and positions are as broadcast from the a/c. However, the time data is actually given to millisecond precision (not just to the second).

In that last minute up until 23:12:04Z (when the data stopped being able to be collected) the plane was flying in a straight line at about 32000 ft, at about 480 knots, in a NW bearing.

Thus we can get pretty accurate estimates of the speed data by calculating across several successive data points instead of using just one and the next one. Also use the milliseconds. This seems to show a sudden slow down at the end of the minute: down to say 300 knots.

I will publish the calculations when I get a moment if no-one else does first.

Note also that there is apparently some separate radar data gathered for a little while after 23:12.
7th Jan 2015, 01:39

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Here's a better view of the sonar scan image.

7th Jan 2015, 02:09

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Fuselage width

The sonar scan image 2 posts up, reports the width of the selected section as being 4.6m... this corresponds fairly closely to the A320 fuselage width of 3.95m.

The typical beam-to-length ratios for smaller boats are 2:1 (up to about 6m length) to 5:1 for larger racing sailboats over 10m.

It might fit for a boat, but the fuselage width is very close to being spot on.
7th Jan 2015, 02:13

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Originally Posted by Lost in Saigon
Fact.....

This image shows QZ 8501 on a bearing of 141 deg, range 52.9 miles from RAFIS which gives a position of 03.5874 S, 109.6834 E. (03 deg 35' 14.8"S, 109 deg, 41' 00.1" E)

The best estimate I can make of the position of EK409 by plotting on a chart, based on that screen shot is 03.34175 S, 109.08359 E (03 deg 20' 30.3" S, 109 deg 05' 00.9").

Does that fit with any of the ADS-B data coming from FR24 or other sources? Flightware actually gives that position of EK409 directly on track on M635, so no doubt their algorithms are only making a guesses at this stage of the flight.
7th Jan 2015, 02:20

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Does that fit with any of the ADS-B data coming from FR24 or other sources?
No, it is about 60 miles WNW of the last reported position according to the ADS-B data from FR24 ( 3.990 s 110.226 e).
7th Jan 2015, 02:30

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If both engines flamed out.. and the plane started to glide. What electrically are we left with that would be on in an A320, with batteries and then assuming the RAT deploys.. Full coms? Would ADB-S still transmit and if so would the GPS system be still available to it? Find it strange the last few broadcasts that FR24 received had no location data.
7th Jan 2015, 02:37

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Training Wheels

Is this a computerize image that can only be understood if you know the algorithm or is the general viewer supposed to view it against knowledge of the shape of an A320 from available images or sketches on the internet?
7th Jan 2015, 02:44

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The last three ADS-B data points from FR24 were:

23:12:04 3.990 s 110.226 e
23:12:34 2.990 s 110.226 e
23:12:37 2.990 s 110.226 e

All the prior data points (before 23:12:04) were just a few seconds apart and they each had a distinct position. But the last two here kept the last position from 23:12:04, also, there was a thirty second interval between the last "normal" data point (23:12:04) and the next one with no position update.

From what I know, FR24 works with predictive data at times. So these last two data points might be generated by FR24's software and not QZ8501. (This is just a guess on my part.)
7th Jan 2015, 03:45

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ASN Aircraft accident Boeing 747-131F 5-8104 Madrid

(Was reply to removed post that asked if 'large aircraft had ever been brought down by lightning')

.

Last edited by aircarver; 7th Jan 2015 at 14:01. Reason: Removed post made this an orphan
7th Jan 2015, 04:30

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Report the Tail Has Been Found

The tail of AirAsia flight QZ8501 has been found, Indonesia's search and rescue chief says.
7th Jan 2015, 04:31

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There are lots of reputable news agencies now reporting that the search team has found the tail of the aircraft .

BBC News - AirAsia QZ8501: Tail of crashed plane found
7th Jan 2015, 04:36

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lomapaseo,

It's not a processed image, but side-scan sonar images are difficult to interpret and often require expert knowledge

My guess is that the sonar fish was moving parallel to and near the right side of the image. Bright areas indicate objects that reflect an significant amount of energy back to the fish and are therefore sticking up above the sea floor. Behind the bright areas, you typically see dark areas that are shadowed from the beam. Note the shadow to the left of the box, behind the "object".

See here for more details:

https://en.wikipedia.org/wiki/Side-scan_sonar
7th Jan 2015, 04:51

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Tail found

The tail of AirAsia Flight 8501 has been found in the Java Sea, the head of Indonesia's search and rescue agency said Wednesday.

Bambang Soelistyo, chief of the rescue agency, known as BASARNAS, told reporters at a news conference that tail numbers were visible on wreckage. Finding the tail is significant because it may contain the plane's data recorders.

The announcement comes after the USS Fort Worth, a littoral combat ship assisting with the search for the wreckage, spotted objects that could be pieces of debris from the Airbus A320
7th Jan 2015, 04:52

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The tail of AirAsia flight QZ8501 has been found, Indonesia's search and rescue chief says.
Also some video from a submersible is being played.
7th Jan 2015, 05:01

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Originally Posted by SAMPUBLIUS
The tail of AirAsia Flight 8501 has been found in the Java Sea, the head of Indonesia's search and rescue agency said Wednesday.
AirAsia Flight QZ8501 plane tail confirmed found

“We have successfully obtained part of the plane that has been our target. The tail portion has been confirmed found,” search and rescue agency chief Bambang Soelistyo told reporters in Jakarta.
good news - hopefully the black boxes are safely within.