Russian A321 Down in Egypt

[DEFCON]

If you look at the aerial view of the charred wreckage, it would appear the fuselage was detached at the trailing edge prior to ground impact. The clean section of the tail remaining is not long enough to fit and so it would seem that a fairly substantial piece of the fuselage is missing from the photographic record. This section, when we see it, will probably provide the evidence necessary to determining whether the aircraft was taken down by a bomb, or not.

[dagger]

According to the NYT correspondent, US sources say the CVR contains sound of explosion, though it's not yet definitively established to be a bomb. But not some kind of cascading event.

[blues deville]

According to the NYT correspondent, US sources say the CVR contains sound of explosion, though it's not yet definitively established to be a bomb. But not some kind of cascading event.

From my training the first evidence of an explosive decompression on an airliner will generally be a loud bang. It does not necessarily mean a bomb exploded but I guess this version of the event sells more newspapers.

[DEFCON]

The sound Dagger's referencing is suspected to be evidence of an explosion, but because it only lasted a couple of milliseconds before the tape ended, although suspicious, the noise can't prove the theory. IOW's, they say the sound could be a product of the fuselage fracturing versus being related to an exploding bomb.

[blues deville]

Some reports say the FO had complained about the maintenance or condition of this a/c. Was there an MEL issue or problem with elevator/stab trim? As already mentioned on this thread there are no photos so far of this part of the plane.

Edited. It is also being reported that Metrojet was behind in payments for ground handing at sharm el-sheikh airport. Unfortunately airline financial issues have an adverse effect on the parts/spares department too.

[boestar]

Ever pop a balloon? It goes Bang. Airplanes are just Aluminium Balloons.

[DEFCON]

“Some reports say the FO had complained about the maintenance or condition of this a/c”

We hear these sorts of comments being attributed to an often dead flight crew member, which leads to a question; if the aircraft are / were in such deplorable shape, why would a professional pilot continue to fly them?

Now, I’m pretty sure I can answer that one all by myself, but the true question remains outstanding; how can pilots ever justify the claim the group deserves professional status when they regularly demonstrate the absence of the kind of moxy the job demands?

[blues deville]

Some reports say the FO had complained about the maintenance or condition of this a/cWe hear these sorts of comments being attributed to an often dead flight crew member, which leads to a question; if the aircraft are / were in such deplorable shape, why would a professional pilot continue to fly them?Now, Im pretty sure I can answer that one all by myself, but the true question remains outstanding; how can pilots ever justify the claim the group deserves professional status when they regularly demonstrate the absence of the kind of moxy the job demands?

I'm sure pilots at Air Koryo (North Korea) don't have a choice but most do and will leave.

http://www.dailymail.co.uk/travel/travel_news/article-2791675/inside-north-korea-s-soviet-era-planes-s-like-fly-world-s-one-star-airline.html

[Woody Pusher]

A French newspaper "Le Point" is now reporting that the contents of the CVR have been recovered and listened to. The final sounds were deemed to be that of an explosion.

http://www.lepoint.fr/monde/sinai-l-attentat-confirme-par-les-boites-noires-06-11-2015-1979795_24.php

Egyptian authorities will be holding a press conference on Saturday in Cairo at 1700 EET (1500 UTC).

EDIT:: Re "sound of explosion" [my translation] .. but with analysis, the initial sounds of a violent decompression is probably what will be revealed.

[inchman]

Don..

My point as to the location of the DFDR has to do with, in a case of on flight breakup, the severing of the data feed, not an issue with general data quality.

In this case, for example, we have nothing... no CVR recordings, no pressurization info, no flight control positions... no trajectory after breakup.

The FAR and CAR rule was created based on aircraft design, fire resistance and recorder technology from more than 40 years ago. I am of the opinion that the benefits of having non-severed feed in the event of in flight breakup, where trying to determine the cause is clearly quite ethereal, exceeds the very low potential of having the recording media unreadable due to impact if the recorder was installed closer to the flight deck and flight control computers.

[DEFCON]

Who knows, maybe it's technically possible Inchman , but impact isn't the only consideration; fire too can easily destroy one of these units.

At Dryden both 'state of the art' boxes were destroyed by fire consequent to pooling fuel. The loss fueled, no pun intended, a considerable amount of discussion with respect to the design and location of the boxes in all quarters, including the manufacturer. After all had been said and done to investigate the matter it was clear to everyone that the design was as robust as technically feasible and the location the best possible regardless.

I'd like to hear if anyone comes across any information regarding the specifics of the forces that would have been necessary to impart so much damage to the CVR on the Metrojet 321.

[Don Hudson]

inchman, thanks for clarifying the argument for a different location. I wouldn't disagree with the suggestion so much as ask questions about how one determines any new location that improves on the present one. The likelihood of survival when in the tail was the original reason for the location. Given almost sixty years of experience in accident investigation using recorders, where might an acceptable, alternate location be?, (put another way, what parts have statistically survived best?)

Does the recorder need to be on the aircraft at all?

In imagining what technological developments are possible, one can foresee a wireless sensor design where, in addition to the thousands of sensors already installed in aircraft like the A380 & the B787, sensors that could measure flex and stress and perhaps even local pressures in the boundary layer at numerous locations on the skin of the aircraft. It is now possible to imagine strategically-placed video sensors which would record inaccessible areas of the interior of the aircraft. Such developments would turn each aircraft into a "living" commercially-based research laboratory as well as fulfilling original purposes of accident investigation.

Setting aside the design, testing, certification & regulatory processes for a moment, the easiest solution that we could imagine would be a wireless one with all sensors capable of transmitting their data to a central, solid-state recorder which was built to be, say, robust-by-a-factor-of-10, which could therefore be located anywhere in the aircraft, or perhaps not on the aircraft at all and, as some have suggested after MH370's disappearance, the solution could be real-time transmission of flight data, of even a limited dataset. The problems largely become technical, not philosophical, although hacking threats and legal issues (use of intercepted data) remain philosophical and political.

[inchman]

Given almost sixty years of experience in accident investigation using recorders, where might an acceptable, alternate location be?, (put another way, what parts have statistically survived best?)

I think that this is the salient point. Is there any proof that the tail does provide a more survivable location, or is that just it seems intuitive that the tail of the aircraft would have lower impact loads due to crush related energy absorption, at least in the longitudinal axis? But aircraft rarely crash like they do in cartoons.... straight down.

I think it's because of that intuitive sense when the rule was made and has become "because we have always done it that way" and changing laws and rules is always very difficult. If we think back to some of the more recent accidents, I would suggest that the tail took a much force as the nose in a lot of them. Even in our own backyard, the Halifax incident would have hit the tail harder than the nose.

As far as fuel fires go, DEF, fuel flows where it flows... sometimes forward and sometimes back. The nose of the aircraft is as far from the fuel and ignition source as the tail. And the aircraft involved in Dryden was two or three generations of design and thermal engineering ago. We were still using asbestos for fire suppression back then (although I don't know what they were using in DFDRs).

I agree that the remote solution is the best one from a technical perspective. Cost and, as you say, philosophy will eventually rule on it.

Two DFDRs... one in the front, and one in the back would probably provide a cheaper and quite reliable solution than trying to stay real-time remotely. The remote solution would only have helped in a couple of cases in the recent past anyway. Making location information mandatory, sure... but that's a thousandth of the amount of data that would have to be sent to have a timely feed of DFDR data and is subject to all kinds of other issues. If an aircraft is completely out of control or the IRUs had kicked off as was the case in AF, or if this aircraft was over water and unfindable, would the antenna have been able to align with a satellite to send a complete set of data? And if the data compiler was not in proximity to the data source (the E&E compartment) and its feed or the satellite antenna conduit on board was severed by the breach we would be exactly where we are right now....data, data, data... momentary scratchy noise... nothing.

[Don Hudson]

Thanks, inchman.

Re changes to the location recording system, a couple of data points that would have to be considered - both the DFDR & the CVR were readable in two widely-separated accidents and enabled investigators to determine what happened: AF447, after two years under crushing pressures at 12,000ft underwater, and the Turkish DC10 crash at Ermenonville in 1974, which went in at 425kts.

The case where data stops due loss of signal, (due unpredictable patterns of structural breakup or fire) are resistant to on-board solutions period, which could be resolved by wireless-transmitting sensors with their own tiny power supply. The SW111 recorders quit after losing on-board power, which argues for independent, in-situ power supplies which I think is a far more arguable case than re-location.

Slight o/t rabbit trail but still to do with data transmission: - In terms of actually losing an airplane somewhere on earth, there is absolutely no excuse for any airliner to be completely lost like MH17.

I have previously pointed out companies like Skytrac provide real-time aircraft location and reporting, plus the ability to provide real-time data-monitoring from the same sensors that feed the DFDR & QAR, for things like overspeeds, flap exceedences etc. - those things that require maintenance action at the next station stop. We just tracked-recorded a round-the-world operation - if we wanted to know where the airplane was, we just signed into the program and voila...over the Bering Strait at 10,600m, etc., etc., (and it can't be shut off from the cockpit). This isn't just a plug for the company - it ain't braggin' if they can actually do it!

[DEFCON]

Older figures, but the tail section is known to survive 67% of all crashes, which makes it the preferred location.

[inchman]

DEF,

There are two parts of that statistic that bother me.

First, the survival of the tail section is not the criteria that should be used. I suppose if you were trying to prevent an egg from breaking, then the tail section would be the best place to put it. But the DFDR is a very robust unit. There are probably many places on board accident aircraft where it would survive at the same rate as if it was located in the tail.

Second, single statistics, where a comparison should be made, are irrelevant. It's quite possible that another part of the aircraft has the same or better survivability. But when a single statistic of greater than 50% is shown, it implies that the hypothesis is valid when the facts may be otherwise. If you were buying a TV and consumer reports gave a single TV a 87 grade and gave no ratings to other TVs, does that mean that it is the best one?

The bottom line is that, if the DFDR doesn't have the relevant information because it cannot access critical data because of up to 200 ft of potential wire severance in the event of a fuselage breach, it is as good as being in the least survivable part of the aircraft... maybe worse. It is possible, for many accidents, to identify the turning point and subsequent actions of the crew. In accidents like this, the turning point is identified with less than a second of noise and no subsequent

Don, you mentioned a self-powered unit to keep recording critical information after ship's power is lost in those relatively rare situations where an accident occurs as well but, beyond telemetry, you seem to accept that it's ok to be guaranteed to lose that same critical information in an accident scenario when the tail is removed. Having the DFDR in the front of the aircraft makes it much more likely that it could be attached to the hot battery bus, too, so it could remain powered during loss of electrics.

Would we know more, or been able to draw valid conclusions sooner, about what happened to TWA 700, Swissair 111,CI-611 or 7K-9268 if we had data for a few more seconds of CVR or DFDR?

Kinda dragging this out a bit. Sorry about that.

[Moon The Loon]

Great discussion for the lesser knowledgeable folks like myself. But all discussion focuses on a single DFDR.

What about the idea of more than one DFDR in multiple locations throughout the aircraft (yeah, there would be a weight penalty)? Each could record independently of another, but from the same sensory pick-ups. Ideally the recorded information on each of them would be identical. This removes the need for WiFi which would inherently involve "noise".

Chances of more than one of the recorders surviving would be good for most similar type events, but probably not good during a catastrophic impact such as the 9-11 airframes experienced.

Just a thought from left field...

[Woody Pusher]

Thanks to a Russian TV program video I noticed something that seems to fit with the reason for and the sequence of the break-up. The following is a single frame from the video and is looking forward through the area that housed the THS and through the missing RPB to the aft galley area.

http://oi64.tinypic.com/2ev9ctd.jpg

The RPB or Aft Pressure Bulkhead has clearly been ruptured on the portside as seen in the image above. This explosive device may have been aft or forward of the RPB; though I suspect it was forward. The blast has been powerful enough to remove the RPB and sheer the remainder of the tail section, taking the APU out at the same time. Part of the VS remained, but the rudder was taken out, along with the THS.

The DFDR and CVR were removed from the equation at this point, and it would be of interest to know if they were recovered together, or separately.

I also suspect that due to the other skin peel-back forward of the RPB that has been imaged, the shock-wave from the blast probably incapacitated everyone on the aircraft at the same time.

A substantial amount of explosive material was involved to create the damage seen, and claims that the THS could have caused this on its own are not believable.

[conehead]

What about the idea of more than one DFDR in multiple locations throughout the aircraft (yeah, there would be a weight penalty)? Each could record independently of another, but from the same sensory pick-ups..

Moon; this is the exact setup in the Embraer 170/190. One in the aft, one in the fwd e/e bay. Both units are combined CVR/FDR.

[Moon The Loon]

Thanks Conehead. On reviewing one of Don's posts above, he also makes reference to the idea. I would only add, the bigger the airframe, the more recorders. An A380 for instance might have 10 spread throughout the airframe - that was my thinking.

[Kip Powick]

CBC News Network

."An unnamed spokesperson for the team investigating the crash said the investigators are now 90% sure that the plane was brought down by a bomb".

[DEFCON]

Here are a couple of the pictures I was looking for earlier.

Can anyone from maintenance thats familiar with the series confirm this section of the aircraft comes from the below floor area of the forward end of the rear cargo hold.

I believe the second picture captures a portion of the section of fuselage normally in position ahead of the broken tail section. Its impossible to make anything other than a guess, but its hard to imagine that air loading alone could have been responsible for breaking the body in that manner. Anyway, if anyone can, Id like to know where this piece was located in relation to the main wreckage.

[J.O.]

I believe the first picture is the APU firewall. You can see the APU fire bottle hanging in the centre. It's normally attached in the upper left hand corner so it was obviously broken loose. The bleed duct can be seen in the lower left hand corner.

[DEFCON]

Thanks JO.

The piece did look a bit too small to be the section I wondered about.

[Woody Pusher]

Explosive Traces Confirmed

Reports out of Russia confirm that traces of explosives have been found.

Needless to say, Putin is not best pleased, and retribution will follow.