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On or about July 30, 2015, the initial news could have been worded like: "debris appears to have come from a Boeing 777". As the story evolved, additional details emerged such as the wreckage being part of a 777 flaperon, before being decisively announced.

My question is: what was the forensic/investigative process which would have produced the initial speculative-sounding announcement associating the debris to a 777, before ultimately becoming the more definitive statement?

To put it another way: what steps had investigators taken up to the point of each announcement, and how was the debris recognized very early on as part of a 777 without actually being confirmed as such? Is it investigator experience? If initial identification was made by part numbers, why would there have been any doubt in the announcement?

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    $\begingroup$ A precise citation would be nice ("Medium X stated that Y on date D"), so that we can all reference the same exact wording. $\endgroup$
    – ALAN WARD
    Commented Jul 31, 2015 at 12:03
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    $\begingroup$ How is this on-topic? I understand that it's about a part from a plane, and possibly about MH370, and even that it may be something akin to an NTSB investigation... but the investigative processes are not really aviation... just saying (please note that I did not down-vote or vote to close) $\endgroup$
    – CGCampbell
    Commented Jul 31, 2015 at 13:16
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    $\begingroup$ @CGCampbell Why would aviation accident investigation techniques not be on-topic? Perhaps some chat/meta discussion would be useful? Personally I would simplify the question to "how can accident investigators identify individual aircraft parts?" but that's just my take on it. $\endgroup$
    – Pondlife
    Commented Jul 31, 2015 at 13:51
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    $\begingroup$ @Pondlife I think that the techniques are on topic, but media reporting of those techniques' results are not on topic. This question seems to be asking why the media has no clue what they're talking about when it comes to aviation, and the answer seems obvious. $\endgroup$
    – egid
    Commented Jul 31, 2015 at 18:43
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    $\begingroup$ @egid I agree with that, it's pointless to take media reports literally but I read the question more 'optimistically' as asking how do investigators arrive at a definitive answer? And as I mentioned, I think the question would benefit from being simplified to be more focused on the investigation rather than the reporting. So I think we probably agree on what is answerable here. I thought about editing it, but I hesitated because I might change the OP's intent too far. $\endgroup$
    – Pondlife
    Commented Jul 31, 2015 at 18:54

2 Answers 2

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If you bring an NTSB investigator a piece of 2024 sheet aluminum with zinc chromate primer and a urethane topcoat all they can tell you is "It's 2024 sheet aluminum, with some paint on it." - BUT if you bring them a piece of 2024 aluminum riveted to a structure that looks like this:
Debris photo
and tell them "I found it on an island in the Indian Ocean" they can infer lot more.

In this particular case they've found some debris, and they know a few things:

  1. The debris was found in an area where it's reasonable it could be part of MH370.
    The location isn't conclusive in and of itself, but it's certainly a factor that strongly implies this could be part of the missing aircraft.

  2. The part LOOKS like it came off an airplane.
    It's aircraft aluminum, riveted to a skeleton that gives it an airfoil shape. That warrants further investigation by itself (even if we didn't lose an airplane in that area recently it's clear that some part fell off some airplane at some point in time, and investigators generally want to know which airplane had bits falling off).

That leaves us with the question Could this part have come from the airplane we lost? which is the stage we're at now, and there are many ways to make this determination.

  • You might get lucky and recover the aircraft ID plate, or a chunk of the tail with the N number.
    There's confirmatory testing to be sure it's not a well-perpetrated hoax, but these are pretty definitive identification elements. Unfortunately that's not the case here, so we move on.

  • If you recover what appears to be a control surface you'll usually find a manufacturer stamp somewhere on the part, or a serial number plate. They'll certainly be inspecting this debris to look for that kind of data tag. (The data tag below is from a Piper control surface but Boeing probably uses similar plates).
    Control surface part data tag

  • If you don't find a data tag maybe there's airline livery on the debris.
    This at least lets you know whose plane you've found, but that's not applicable here as the debris in question appears to be painted basic white.

  • Failing all of that you compare what you've found to manufacturer's drawings of the aircraft you think it came from and see if the dimensions match any parts or sections of that aircraft.

There are other possible steps and confirmatory testing involved (metallurgy, mass spectrometry on the paint, etc.) to determine if it's likely this part came from the aircraft you think it did, but that's getting into the territory where you'd be better off signing up for training courses in accident investigation.

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    $\begingroup$ Of course, in this particular case, if they can confirm that it is indeed a 777 flaperon, then they've also effectively confirmed that it was from MH370, since only 3 other 777s have ever crashed and none of the others were anywhere near the Indian Ocean (and all 3 were on land, meaning that their flaperons were recovered immediately... in two of those cases because they were still attached to the almost completely in-tact wings.) $\endgroup$
    – reirab
    Commented Jul 31, 2015 at 18:53
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    $\begingroup$ @reirab Yup, the 777's excellent safety record makes it much easier to figure out which crash any given piece of debris came from :) $\endgroup$
    – voretaq7
    Commented Jul 31, 2015 at 18:58
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    $\begingroup$ This from a CNN article on the debris: "The source said Boeing investigators are basing their view on photos that have been analyzed and a stenciled number that corresponds to a 777 component." They didn't indicate who those "sources" were. Another source told CNN that Boeing engineers have seen a part number -- 10-60754-1133 -- in photos of the component. A Boeing parts supplier confirmed the number was on a seal associated with the Boeing 777, the source said. Images of the debris appear to match schematic drawings for the right-wing flaperon from a 777. $\endgroup$
    – TomMcW
    Commented Aug 1, 2015 at 22:37
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    $\begingroup$ @AnthonyX Also, only a few aircraft types even have flaperons at all and this one is the same dimensions as the one on the 777. That narrows it down a lot, even before confirming with part numbers and such. $\endgroup$
    – reirab
    Commented Aug 3, 2015 at 3:29
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    $\begingroup$ The Aviation Herald now quotes Malaysia's Transport Ministry statement (on Aug 2nd 2015) that the part has been confirmed to be a flaperon from a B777 and that they are now trying to verify whether it was indeed from 9M-MRO. $\endgroup$
    – Jan Hudec
    Commented Aug 3, 2015 at 9:34
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They know the debris is from a 777 because the parts have part numbers on them which are unique to that model.

Since all other 777s are accounted for and no other 777s have crashed in the Indian Ocean, the flaperon ccould only be from MH370.

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