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BREAKING NEWS: airliner missing within Egyptian FIR

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BREAKING NEWS: airliner missing within Egyptian FIR

Old 31st Oct 2015, 15:46
  #81 (permalink)  
 
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FR24 is an amateur system, with limitations on data accuracy. I do not profess to be an expert, but my understanding is that the way the system works is it receives simultaneous data from a number of receivers in well covered areas, and retains data which match from a number of sources and drops the one that disagrees. In areas of sparse coverage this is not possible, and any data received from a single source is taken as valid. Errors may be introduced to the data for several reasons, especially if the receiver is near the range limit. Single spikes (like in this case) are almost always attributable to some data error, while constant data (no change whatsoever) is a sign of extrapolation.
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Old 31st Oct 2015, 15:53
  #82 (permalink)  
 
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Forget the video and look at the initial adsb data from Flightradar that has been posted on the aviation safety networks webpage:

Graphic - Aviation Safety Network

A stall, recovery and then a second stall

Last edited by tubby linton; 31st Oct 2015 at 16:19.
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Old 31st Oct 2015, 16:05
  #83 (permalink)  
 
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Spot on.... Sticking to facts on a rumour network would make the site totallu unworkable.....

"A plane has crashed in xxxxx this thread is now closed until the official accident report is out" ....... Six months later "the report can be found at www.xxxxxxxxxx.c*m , this thread is now closed"
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Old 31st Oct 2015, 16:33
  #84 (permalink)  
 
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(RT.com)
German carrier Lufthansa and Air France-KLM have decided to avoid flying over the Sinai peninsula while they wait for clarity on what caused a Russian airliner carrying 224 passengers to crash in the area, spokeswomen for the carriers said on Saturday.
Any NOTAM updates while at it?
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Old 31st Oct 2015, 16:36
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The vs data being linked shows 6000 down to 8000 up in 3 seconds. Them are some G's, or the static source was experiencing changing values.
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Old 31st Oct 2015, 16:37
  #86 (permalink)  
 
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tubby linton, I wonder, what if we considered that at/after 06:12:57Z in the ASN image of the "vertical speed", (in quotes, because, as I think you know, this isn't data from the SSFDR), that the ADSB flight data might not be what actually occurred?
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Old 31st Oct 2015, 16:40
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The vs data being linked shows 6000 down to 8000 up in 3 seconds. Them are some G's.
Such data is often wrong, flightradar have a history of releasing this type of questionable data (both for accident and non-accident flights) and, quite frankly, I wish they'd behave a bit more responsibly.
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Old 31st Oct 2015, 16:48
  #88 (permalink)  
 
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Forget the video and look at the initial adsb data from Flightradar that has been posted on the aviation safety networks webpage:

Graphic - Aviation Safety Network

A stall, recovery and then a second stall
It's worth pointing out that the data track shown there is for the last minute of recording, with the variations in about 30 seconds of a time frame.

Stall recover and enter a second stall in under 30 seconds, in an A321?
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Old 31st Oct 2015, 16:49
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Flightradar have published a csv file of the data which can be found here. Obviously this will not be as accurate as the fdr data, but it does show trends of what may have happened.
Crash of Metrojet Flight 7K9268 | Flightradar24 Blog
The recorded ground speed goes from 404 to 246 , increases and then falls to a last recorded value of 62.
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Old 31st Oct 2015, 17:03
  #90 (permalink)  
 
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Ground based terrorism?

Both Lufthansa and Air France have announced that they will not fly over the Sinai until further notice.

Have they received further information/briefings.

Knee jerk reaction?


And now BA are avoiding the area. It does raise the question, have security services briefed airlines and if so the reason would be rather obvious.
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Old 31st Oct 2015, 17:05
  #91 (permalink)  
 
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Flightradar have published a csv file of the data which can be found here. Obviously this will not be as accurate as the fdr data, but it does show trends of what may have happened.
Crash of Metrojet Flight 7K9268 | Flightradar24 Blog
The recorded ground speed goes from 404 to 246 , increases and then falls to a last recorded value of 62.
Just a rudimentary run through that data. you can see at some points a heading variation of 25 deg in a second. compare that to standard rate turn and we can get some idea of what forces were in play to the airframe, and indeed those contained within it following the cause of the departure.
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Old 31st Oct 2015, 17:06
  #92 (permalink)  
 
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stuckgear;
Stall recover and enter a second stall in under 30 seconds, in an A321?
I agree with your implied conclusion...no, I don't think this is a stall/secondary stall. We might say this could be "spurious data"...

tubby linton;
Obviously this will not be as accurate as the fdr data,
No, and we don't know how FL24 creates the vertical speed data. If it is derived from P.Alt then it is only as good as the P.Alt parameter. A typical data frame on an A321 will have both inertial, recorded and perhaps GPS VSI parameters, (older data frames such as those installed on the B737 Classics derive vertical speed from P.Alt).
. . . but it does show trends of what may have happened.
It may or may not, depending upon other, corroborating parameters which FL24 is incapable of presenting because ADSB doesn't have them. I would like to know what the cabin pressure and cabin rate-of-climb parameters have to say, for example.
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Old 31st Oct 2015, 17:06
  #93 (permalink)  
 
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Comparison of a more reliable MANPADS shootdown. AN30 in this case. Significantly different.

https://youtu.be/5Z7BCUEWQCg
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Old 31st Oct 2015, 17:09
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Just a rudimentary run through that data. you can see at some points a heading variation of 25 deg in a second. compare that to standard rate turn and we can get some idea of what forces were in play to the airframe, and indeed those contained within it following the cause of the departure.
Once again, you are assuming that the FR24 data is accurate. Prior experience suggests that this is often not the case. Sometimes this is because FR24 fudges the data, more often it's because bad data is transmitted.
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Old 31st Oct 2015, 17:12
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The Russian airline whose plane crashed in the Sinai region on Saturday says the aircraft was in good shape and the pilot was experienced.

In a statement on its website, Moscow-based Metrojet says the A321 received required factory maintenance in 2014.

The statement identified the captain of the plane as Valery Nemov and said he had 12,000 air hours of experience, including 3,860 in A321s.
The Latest: Airline says crashed plane was in good shape
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Old 31st Oct 2015, 17:14
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Graphic

They've used an algorithm to fit their curve to those points, but essentially you've got 8 sec of VS approaching -6,000; then 6 sec of VS approaching +4,000; then 8 sec of VS approaching -7,000; then 5 sec of VS approaching +8,000; and the data ends.

In that last oscillation the VS changes neg to pos by about 15,000 fpm (250 feet per sec) in 6 seconds.

A G-meter would show oscillations between about -.5 and +2.5 under those circumstances.

Last edited by thcrozier; 31st Oct 2015 at 17:57.
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Old 31st Oct 2015, 17:14
  #97 (permalink)  
 
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I agree with your implied conclusion...no, I don't think this is a stall/secondary stall. We might say this could be "spurious data"...
Indeed. and an explosive event would of course produce a pressure wave in its propogation, which would be recorded by pressure reading instrumentation.

Last edited by stuckgear; 31st Oct 2015 at 17:15. Reason: typo/spelling
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Old 31st Oct 2015, 17:15
  #98 (permalink)  
 
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Given the credibility of the Egyptian (Egyptair 990) and Russian (MH 370) air investigation teams, it may well be that the most authoritative facts and interpretations appear on this site or others like it. At this stage it is not possible to separate useless from useful speculation.

It seems to me that posts here after any major civilian crash fall into one of two groups: speculators, most of them well-meaning, trying to piece together an understanding of what happened as information becomes available; and scolders, who criticize the speculators for jumping to unjustified conclusions and ask them to stop doing so. Is it just me, or does the second group not sound like a bunch of Peeping Toms lecturing everybody else to put their clothes back on and pull the curtains?
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Old 31st Oct 2015, 17:17
  #99 (permalink)  
 
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Vertical speed data will be from the ADIRU.
Does anybody know the projected sector time for this flight?
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Old 31st Oct 2015, 17:18
  #100 (permalink)  
 
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The Russian airline whose plane crashed in the Sinai region on Saturday says the aircraft was in good shape and the pilot was experienced.

In a statement on its website, Moscow-based Metrojet says the A321 received required factory maintenance in 2014.
Seeing as the aircraft, as an asset, was owned by significant major lessor in the market, i have no reason to doubt that.

A prerequisite of lessors is that the aircraft residual value is protected by maintenance demands as set forth in the lessor terms.
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