Black box data is the ne plus ultra of aircraft accident investigation. But it is not the only kind of physical evidence. Pieces of debris—in particular, their dents and fractures — can tell a vivid story by themselves.
There are five basic ways that an object can break. The two most important for our present discussion are tension and compression. A tension failure occurs when something is pulled apart—think of pulling the ends of a piece of string until it snaps. Compression is the opposite; it’s what happens when something is crushed by a weight or smashed in an impact.
When a plane crashes, it’s common for all different parts to exhibit different kinds of failure. Imagine a plane whose wingtip hits a tree. The impact would crush the leading edge of the wingtip—compression failure—and then wrench the wing backwards from the body of the plane, causing a tension failure at the forward wing root and compression failure at the aft end.
By collecting many pieces of debris after a crash, investigators can place the mechanical failures in a chronological order to tell a story that makes sense, much as you might arrange magnetic words on a refrigerator. This is how the mystery of TWA 800 was solved. When the fuel tank exploded, the pressure pushed the fuselage skin outward so that it came apart like a balloon popping. The plane broke into two major parts that smashed apart when they hit the ocean. Thus tension failures predominated in the first phase of the catastrophe and compression failures predominated later.
So now let’s turn to the issue at hand. What story do the pieces of MH370 debris tell?
In April of this year the Malaysian government published a “Debris Examination Report” describing the 20 pieces of debris that were deemed either confirmed, highly likely or likely to have come from the plane. For 12 of them, investigators were able to discern the nature of the mechanical failure. Some key excerpts:
Item 6 (right engine fan cowl): “The fracture on the laminate appears to be more likely a tension failure. The honeycomb core was intact and there was no significant crush on the honeycomb core.”
Item 7 (wing-to-body fairing): “The fibres appeared to have been pulled away and there were no visible kink on the fibres. The core was not crushed; it had fractured along the skin fracture line.”
Item 8 (flap support fairing tail cone): “The fracture line on the part showed the fibers to be ‘pulled out’ showing tension failure. Most of the core was intact and there was no sign of excessive crush.”
Item 9 (Upper Fixed Panel forward of the flaperon, left side): “The fracture lines showed that the fibres were pulled but there were no signs they were kinked. The core was intact and had not crushed”
Item 12 (poss. wing or horizontal stabilizer panel): “The carbon fibre laminate had fractured and appeared to have pulled out but there was no crush on the core.”
Item 15 (Upper Fixed Panel forward of the flaperon, right side): “The outboard section had the fasteners torn out with some of the fastener holes still recognizable. The inboard section was observed to have signs of ‘net tension’ failure as it had fractured along the fastener holes.
Item 18 (Right Hand Nose Gear Forward Door): “Close visual examination of the fracture lines showed the fibers were pulled and there was no sign of kink.”
Item 20 (right aft wing to body fairing): “This part was fractured on all sides. Visual examination of the fracture lines indicated that the fibers appeared to have pulled away with no sign of kink on the fibers.”
Item 22 (right vertical stabilizer panel): “The outer skin had slightly buckled and dented but the inner skin was fractured in several places…. The internal laminate seems to be squashed.”
Item 23 (aircraft interior): “The fractured fibres on the item indicated the fibres were pulled out which could indicate tension failure on its structure.”
Item 26 (right aileron): “The fitting on the debris appeared to have suffered a tension overload fracture.”
Item 27 (fixed, forward No. 7 flap support fairing): “One of the frames was completely detached from the skin. It may be due to fasteners pull through as the fasteners’ holes appeared to be torn off with diameters larger than the fasteners.”
Note that all of these but one failed under tension. The exception is item 22, which came from the tail—specifically, from near the leading edge of the vertical stabilizer.
It’s particularly remarkable that Item 18, the nose gear door, failed under tension. (Image at top) If, as the Australian authorities believe, the plane hit the sea surface after a high-speed descent, this part of the plane would have felt the full brunt of impact.
Bill Waldock, a professor at Embry Riddle University who teaches accident-scene investigation, says that if MH370 hit the water in a high-speed dive, you would expect to see a lot of compression, “particularly up toward the front part. The frontal areas on the airplane, like the nose, front fuselage, leading edge of the wings, that’s where you’d find it most.”
I spoke to a person who is involved in the MH370 investigation, and was told that officials believe that that observed patterns of debris damage “don’t tell a story… we don’t have any information that suggests how the airplane may have impacted the water.” Asked what kind of impact scenario might cause the nose-gear door to fail under tension, it was suggested that if the gear was deployed at high speed, this could cause the door to be ripped off.
This explanation is problematic, however. According to 777 documentation, the landing gear doors are designed to open safely at speeds as high at Mach 0.82 — a normal cruise speed. The plane would have to have been traveling very fast for the door to have been ripped off. And to be deployed at the end of the flight would require a deliberate act in the cockpit shortly before (or during) the terminal plunge.
The experts I’ve talked to are puzzled by the debris damage and unable to articulate a scenario that explains it. “The evidence is ambiguous,” Waldock says.
In a blog post earlier this month, Ben Sandilands wrote, “Don Thompson, who has taken part in various Independent Group studies of the mystery of the loss of the Malaysia Airlines in 2014, says some of these findings support a mid-air failure of parts of the jet rather than an impact with the surface of the south Indian Ocean.”
A mid-air failure, of course, is inconsistent with the analysis of the Inmarsat data carried out by Australian investigators. So once again, new evidence creates more questions than answers.
UPDATE 5/24/17: Via @ALSM, here’s a diagram of the front landing gear and doors:
UPDATE 5/25/17: In the comments, we discussed the possibility that the front gear door could have come off in the process of a high-speed dive. @ALSM speculated that the loss of engine power upon fuel exhaustion could have led to loss of hydraulic pressure, which could have allowed the gear doors to open spontaneously, and then be ripped off in the high-speed airstream. But he reported that Don Thompson had dug into the documentation and confirmed that following a loss of hydraulic power the gear would remain stowed and locked. Thus it seems unlikely that the gear door could have spontaneously detached in flight, even during a high-speed descent.
UPDATE 5/25/17: There’s been some discussion in the comments about flutter as a potential cause of inflight breakup, so I thought it would be apropos to add a bit more of my conversation with the accident investigator involved in the MH370 inquiry.
Q: Does the MH370 flaperon look like flutter to you?
A: In a classic sense, no, but where you would be looking for flutter would be on the stops, on the mechanical stops that are up on the wing, so the part of that piece that came out. And in looking at that piece, you’ve got different types of failures of the composite skin that don’t appear to be flutter.
Q: What does it look like?
It just looks like kind of an impact-type separation. So it looks like you’ve drug that thing either in the water or on the ground or something. But it’s a little hard with that one because you don’t have any other wreckage, so, one of the keys — you don’t base anything on one small piece, you’re trying to look at kind of the macroscopic view of all the wreckage to make sure that, “Oh, if I think this is flutter do I see the signatures elsewhere on the airplane?” Typically we won’t base it on one piece like the flaperon.
To provide some context, we had earlier talked about the phenomenon of flutter in general:
Q: I can think of a couple of cases where there was flutter, where the plane got into a high speed descent and stuff got ripped off.
A: Yup.
Q: Where would that fall in the bestiary of failures that we talked about earlier?
A: So flutter’s kind of a unique thing, and it’s based on aircraft speed and structural stiffness. So, you know, when those two things meet you get this excitation, an aerodynamic excitation of a control surface which will become dynamically unstable and start going full deflection. So for a flutter case you generally look at the control stops—so there’s mechanical stops on all the flight controls—and you look for a hammering effect on the stops. So repeated impacts on the stop will tell you that, hey, maybe you’ve got a flutter event.
Q: But if you see the piece—there was a China Airlines incident, the elevator was shredded, or part of it was ripped off. What would that look like?
A: Mm-hmm. You know, it’s going to be different for every single case. Sometimes that flutter will generate the load in the attachment points, break the attachment points, and other times it will tear the skin of the control surface, and so you’ll see this tearing of the skin and the separation of rivet lines, and everything. I’ve seen both. I’ve seen a control surface that comes apart at the rivets, and flutters that way, and I’ve seen them where it generates loads to break the attachment points. It depends on the loads that are created and how they’re distributed throughout the structure.
For his part, Bill Waldock told me that the tensional failure of the collected debris implies a shallow-angle impact. Both experts, in other words, believe the debris is most consistent with a more or less horizontal (rather than high-speed vertical) entry into the water.
This is not consistent with the ATSB’s interpretation of the BFO data unless we posit some kind of end-of-flight struggle, à la Egyptair 990, or last-minute change-of-heart by a suicidal pilot. Either seems like a stretch to me.
I always suspected a failure prior to hitting water. This goes back to the pallet of batteries in the cargo that would have been just below the front half of the plane. What if there cabin pressure loss but the plane could still fly for some time but eventually the plane hit the water after flying for some long period of time with cabin pressure loss. This would explain the auto-pilot scenario as well.
I always suspected a failure prior to hitting water. This goes back to the pallet of batteries in the cargo that would have been just below the front half of the plane. What if there was cabin pressure loss but the plane could still fly for some time but eventually the plane hit the water after flying for some long period of time with cabin pressure loss. This would explain the auto-pilot scenario as well. I still believe in Occam’s razor when it comes to MH370.
sounds like it might have actually attempted a ditching in a shallow area that had various reefs structure to give many random impacts forces to the airframe to twist/torque or cartwheel during impact. various structure failures resulted.
@TBill
What latitudes do you get for your respective flight paths?
Admittedly, I was looking for a viable flight path that ends around the Broken Ridge area as by the time I worked on this, that already seemed to be a good match with the drift studies (and that point is completely outside the areas already searched). Later drift studies gave additional confirmation. But this path also turned out the only one that works exclusively with waypoints as far as I can see (no heading, provided NOBEY/McMurdo was part of the database).
Is it possible that the airplane started to tear apart during the high speed nose dive and produce pieces of debris which failed due to tension? That would fit Inmarsat data. Are there any prevoius cases where that happened?
@Marjan
Yes, absolutely, parts of the plane broke up due to the high speed dive at low altitude and because of greater aerodynamic drag.
Points of comparison are:
Silk Air 185
http://reports.aviation-safety.net/1997/19971219-0_B733_9V-TRF.pdf
(separation of stabiliser parts)
Egypt Air 990
http://www.webcitation.org/5zlFg31jj?url=http://www.ntsb.gov/doclib/reports/2002/AAB0201.pdf
(separation of wing parts, engine, front landing gear door, stabiliser – this is the best case of comparison)
China Airlines 006: separation of landing gear door.
In the case of Egypt Air 990 there were two separate debris fields, the one composed of parts that came off during the high speed dive (tension damage, but no compression damage), the other very small pieces, nearly impossible to identify.
The parts that came off are the better preserved ones that also attract attention if found. Blaine Gibson and others have also found very small pieces that can not be proven to be from MH370. Presumably these are cabin parts and indicate direct impact damage.
Maybe there is a much simpler explanation. The debris might look like torn apart on a scrapyard
@Nederland
A 180S due south heading or track ends up somewhere between 30-34S, with the magnetic heading in the 30-32S range (per Victors paper from BEDAX) and the True Heading 32-34S range. I am thinking it was True heading 32-34S range. I envision an attempt to get over Broken Ridge wall at 31S to deep water. I would not rule out trying to hit a specific feature (eg; the 17500-ft deep spot) but I have not studied landing yet.
It is similar to DrB’s path but DrB was assuming a slightly slanty heading at 181-182 True so he ended up 34.7S (not sure if he has updated final spot). If you notice DrB’s path passes very close to ISBIX.
@Nederland
Thank you Nederland. Do you think it would be far-fetched to say that the aircraft probably didn’t experience phugoid motion which would slow down the descent and extend it flying range? It would mean that there is one more evidence in favor of theory that the aircraft lays close to the seventh arc, 15nm or less, as it was previously suggested by the investigators.
@CosmicAcademy – re:”scrapyard”
Ya like the one in Alice Springs ?
@JeffW
I did not realize they found the nose gear door part, are you saying that is the picture? That would be interesting find…does that tend to disprove fire on the front tire as one theory?
@Casual Observer
” What if there was cabin pressure loss but the plane could still fly for some time but eventually the plane hit the water after flying for some long period of time with cabin pressure loss. ”
It’s a little “out-of-the-box” but I have wondered if the aircraft could have hit the water under vacuum (with cabin pressure below atmospheric pressure) and that could implode the aircraft and suck in water.
There are 4 large low-pressure relief valves in the forward cargo bay that slam open to prevent landing with low pressure inside. So it would depend on how fast those valves react. I have suggested possibly intentional tampering with those relief valves to keep them closed, but that’s probably a long shot.
@Marjan
From an enthusiast-amateur perspective, I am really convinced it was a phugoid motion high speed descent (spiral dive):
For one, the satellite sequence would not work out in the case of a straight (deliberate?) dive: a) the timing isn’t right, MH370 would have crashed before the incomplete handshake could have been initated b) the two BFOs indicate different rates of descent. A straight dive would inevitably be a straigt rate of descent.
Secondly, a phugoid dive releases forces far greater that a straight dive at any time when the motion is reversing. This increases the likelihood of a lot of empennage/wing/door parts coming off during the flight in comparison to a straight dive (like in Egypt Air 990).
@TBill
The arc has – at least in part – been searched up to ~32.5?
I agree, however, that a constant speed path does make sense (although I understood such a path has been largely excluded in the underwater search).
I’d say it is more difficult to find the wreckage in rugged rather than in deep but plane water (if that was the ‘plan’), but of course who knows?
@Nederland
If you look at Arc7 zero altitude position, then the inside the Arc7 area was basically missed in the search from 32.5-35S, outside Arc7 got the better coverage. Also keep in mind there could be some uncertainty in the exact Arc7 line…so possibly nothing inside Arc7 was searched in that spot, and that’s probably where we’d prefer to look (inside Arc7) from a drift analysis perspective.
That would be the argument
@Nederland – re: China Airlines 006
It’s interesting it was able to come out of the steep dive and there was recoverable debris. As for mh370 there should have been multiple debris fields like air china 006 and even more if mh370 crashed into the ocean.
The aircraft could have hit the water at any attitude, it may even have rolled over during the descent.
@TBill, I suppose the front gear door would be evidence against a front-tire fire, but I never put much stock in that idea anyway — I think any kind of accidental cause is grossly inconsistent with the flight path, speed, and altitude, as well as the reboot of the SDU.
@Nederland, Really intriguing comparison you draw with Egyptair 990. Here’s an excerpt from an Atlantic article on the crash: https://www.theatlantic.com/magazine/archive/2001/11/the-crash-of-egyptair-990/302332/
And:
The plane started to come apart in flight after the black boxes had stopped recording, due to loss of electrical power after fuel was shut down to the engines. So, as far as I understand, we don’t know exactly what was going on, but I presume that in addition to the speed brake the landing gear had been deployed in an effort to slow the plane down. If the plane approached Mach 1 on its final dive, as it had briefly before the power died, it’s easy to imagine the front gear getting ripped off. I’m still puzzled by the fact that skin was ripped off the fuselage, too–I’ll try to look into this.
But the analogy raises an interesting idea for MH370. What if MH370’s inexperienced co-pilot somehow failed to notice that the plane had reversed direction? Then, after the plane ran out of fuel and started its terminal death plunge, he wrestled with Zaharie for the controls, deploying the landing gear in an attempt to slow their descent? This would explain the landing gear door, the numerous pieces (many of them trailing-edge) that seem to have been ripped from the plane, the steep descent, and the fact that the plane wasn’t found close to the 7th arc–as with EgyptAir, the steep dive might have been followed by a period of gliding as the co-pilot temporarily gained control.
There are numerous problems with this scenario, but it does make one wonder…
@Jeff
According to the accident report
“The western debris field … contained mainly parts associated with the left engine and various other small pieces of wreckage (including portions of two wing panels, fuselage skin, horizontal stabilizer skin, and the majority of the nose landing gear assembly).”
“It is apparent that the left engine and some small pieces of wreckage separated from the airplane at some point before water impact because they were located in the western debris field about 1,200 feet from the eastern debris field. Although no radar or FDR data indicated exactly when (at what altitude) the separation occurred, on the basis of aerodynamic evidence and the proximity of the two debris fields, it is apparent that the airplane remained intact until sometime during its final descent.”
@Nederland, I think this is potentially very significant given the condition of MH370s’ front gear door. Unfortunately, I also find it a bit hard to understand. As I said before, I don’t see how the nose landing gear assembly could come off unless the gear was deployed. And while it’s not that hard to see why horizontal stabilizer skin might come off in a Mach 1 dive, and perhaps even wing panels, I can’t think of another case (even SilkAir) where the fuselage skin came off.
AA587 lost an engine during its descent over Long Island, I believe that that was due to violent yawing…
judging by satellite data the northern the crash happened the less descent rate it was, which is another reason to favor search area just south of Indonesia
@Jeff
The China Air 006 accident report can be found here:
http://www.rvs.uni-bielefeld.de/publications/Incidents/DOCS/ComAndRep/ChinaAir/AAR8603.html
Apparently, the landing door came off during a dive/climb emergency situation. Could it not just be that landing door is vulnerable like wing parts?
@Jeff
Sometimes it’s the small things that are appreciated the most. Thanks for pulling together the debris items synopsis in one place.
Just on your final line:
“A mid-air failure, of course, is inconsistent with the analysis of the Inmarsat data carried out by Australian investigators. So once again, new evidence creates more questions than answers.”
Could you briefly flesh out a little more on why you think mid-air failure is inconsistent with the analysis of the Inmarsat data?
Thanks.
Jeff:
Good post generally. Glad to see this subject resurface. But to clarify…we are not discussing a “mid-air”. To most pilots, the term “mid-air” means two planes trading paint in mid air. Here, we are discussing in-flight separation, meaning some parts (especially hinged flight control surfaces, gear doors, etc.) appear to have separated from 9M-MRO before main impact, due to excessive speed and potentially flutter conditions.
Regarding your concluding statement…
“A mid-air failure, of course, is inconsistent with the analysis of the Inmarsat data carried out by Australian investigators. So once again, new evidence creates more questions than answers.”
I believe the exact opposite is true, and stated so in a short paper I published the day after the flaperon was discovered almost two years ago now. ( https://goo.gl/2lBErB ) In-flight separation of the flaperon in particular is 100% consistent with the flaperon photos, multiple B777 sim’s by multiple parties, 0019 BFO data, missing AES transmission at 0021, and other analysis. Indeed, every piece of debris you cite above is further evidence of in-flight separation due to a steep final descent, resulting in overspeed.
All of the incidents/accidents cited by Nederland are excellent examples of what overspeed and high G forces can do, and indicative of the parts that tend to come off first, including the nose gear doors.
MH: Re: “…multiple debris fields like air china 006 and even more if mh370 crashed into the ocean….” The simulations indicate a fairly small radius turn by the time the speed is high. Thus, I would expect all the in-flight separation occurred over a small area, perhaps ~10 nm^2.
@Mick Rooney, That’s a great question, I do think I need to unpack that assertion a bit. To recap the Australian investigators’ position, their assumption is that the plane flew south on autopilot, ran out of fuel, electrical power was interrupted until the APU could kick in, and the SDU sent a final signal as the plane was accelerating downward.
So the plane didn’t blow up, and it didn’t crash due to a sudden structural failure. That’s what I meant by the sentence you quoted.
If the gear door was torn off as a result of the gear being lowered, this would have to be the result of a deliberate action, which would run counter to the ATSB’s ghost flight scenario.
However, as Nederland is pointing out, it is perhaps possible that stuff like the front gear door came off as a result of the plane exceeding its flight envelope. I don’t think this could explain all of the pieces that have turned up–for instance, one accident investigator told me the flaperon look like it got torn off during a low-angle impact, such as you’d see during ditching.
I think this is a point worth talking about and discussing.
@ALSM, The overspeed damage to Silkair seems to have been limited to the empennage, unless I’m misreading the accident report.
Regarding China Airlines 006, allow me to paste a rather lengthy chunk from the accident report, because I think it’s very germane:
Note that as with Silkair nothing actually came off except for on the empennage. True, it might have if the descent had continued.
My suspicion is that the gear deployed due to g-loads. I don’t think this would apply if MH370 entered a dive after running out of fuel.
Jeff:
It looks like the nose gear doors (4ea) are actuated via mechanical linkage to the landing gear, which appears to be raised/lowered using a hydraulic cylinder. The gear and doors may become more vulnerable if the hydraulics are lost.
https://goo.gl/S7qhqE
@Jeff @ALSM
Yes, mid-air is somewhat confusing and I’ve seen it used in a number of media reports citing information from the ATSB. I’ve been asked quite a number of times: “Are the ATSB saying it blew up?” Obviously, no. So as Mike E has said, I’m more familiar and comfortable with ‘inflight separation’. I can even live with ‘mid-air separation’.
“If the gear door was torn off as a result of the gear being lowered, this would have to be the result of a deliberate action, which would run counter to the ATSB’s ghost flight scenario.”
I tend to go with letting the evidence (debris) lead you, rather than imposing a scenario on the evidence. There is no evidence – as yet – the gear door was deployed.
Many of the external surfaces recovered show significant signs of fracture, rivets pulled right through, and this remains consistent with an aircraft exceeding its operational envelope due to overspeed/flutter.
What remains stark – in some of the external debris recovered (including flaperon and its adjacent flap) – is the limited or complete absence of compression damage consistent with high velocity impact or some form lower-angle ditch.
@ALSM, That’s a useful image, I’ve added it to the piece.
@Mick Rooney, You wrote, “What remains stark – in some of the external debris recovered (including flaperon and its adjacent flap) – is the limited or complete absence of compression damage consistent with high velocity impact or some form lower-angle ditch.”
Indeed, I think you’re understating the case; I find it remarkable, in a crash that should have been notable for the degree of compression failure, that there is only tension failure visible in 11 out of 12 pieces.
One might argue that pieces severely crushed would lose the buoyancy of their honeycomb core, but I would still expect to see at least some partial crushing. Would be interesting if this kind of analysis were done on AF447 debris, for comparison’s sake.
Comparison to the Silk Air accident:
“The aircraft parts found in the river were highly fragmented and mangled on impact, see
Figure 8. As a result, all parts of the aircraft were mixed together on recovery, making sorting and identification of the many small pieces difficult.”
The pieces that came off, on the other hand, (mostly empennage) were well preserved.
The list above contains only pieces that have been positively identified, not a number of reportedly very small pieces that may be from an aircraft but allow no positive identification. After ~2 years of floating in water (and half on ocean away) it makes little sense to try and piece these together (unlike in the case of Silk Air, where the evidence was collected on site). That means the list above heavily favours large pieces of evidence (that came off in flight) and only very few that broke as a direct result of the impact (because very few of these, even though making up the bulk of the aircraft, could possibly be identified as pieces from the 9M MRO).
I asked Don T. to clarify the nose gear door actuator. He wrote back: “The NLG forward doors each have a dedicated hydraulic actuator (they open only during gear extension/retraction). A regular piston driven actuator. The aft doors are mechanically linked to the main NLG & open as it extends, close as it retracts.”
Debris #3 was the Right Nose Gear Forward Door, thus it had a dedicated hydraulic actuator. At very high speed it could have separated with or without loss of hydraulic pressure, but perhaps more vulnerable without. I’ve long suspected the RAT may have lost it’s prop (or otherwise failed) in a high speed descent, thus loss of what little hydraulic pressure it provided.
Correction: Nose gear door is debris item #18, not #3.
I am pasting few sentences from “MH370 – Search and debris examination update” from Nov 2 2016, p.14:
Some of the simulated scenarios recorded descent rates that equalled or exceeded values derived from the final SATCOM transmission. Similarly, the increase in descent rates across an 8 second period (as per the two final BFO values) equalled or exceeded those derived from the SATCOM transmissions. Some simulated scenarios also recorded descent rates that were outside the aircraft’s certified flight envelope.
I wonder if the new results of debris examination can be linked with the certain flight paths of simulated flight scenarios, particularly ones which would lead to body failure. If there is a correlation, new findings can be incorporated into existing sources of analysis, such as satellite transmission or drift analysis, which would affect the search zone probability distribution map. Hopefully, this can be one more clue that can narrow down the search area and help to convince authorities to continue the search.
@jeff
please don’t laugh.
To perform the search in new areas, the ATSB should maybe contact NASA and ask them what is the status of the probe they want to send to Europa (one of the Jupiter icy moon). Basically they want to send an automatic probe(submarine) that should melt the icy surface, reach the ocean underneath and explorer it as (with some kind of navigation artificial intelligence).
Same probe (or similar) could be sent to the search area in the Indian ocean.
Marijan: Unfortunately, the post FE end of flight analysis is independent of the path analysis (uncorrelated). Following FE, the same descent could have occurred at any lat/lon.
That said, the end of flight analysis cuts the search area by a factor of 5 from what it might otherwise be (200 nm wide to 40 nm wide).
It’s worth a quick review of what the available information tells us about where the plane is, and how the various bits of info and anal;ysis help to reduce the area to be searched.
#1. Based only on the available fuel at 17:21 and 777 performance limits, MH370 could be anywhere within an area of approximately 120 million sq km.
2. Given #1 and adding only 7th arc BTO data, the area is reduced to approximately 3.6 million sq km (assuming up to 360 km wide arc X 10,000 long).
3. Given #1 and #2 and adding BFO data, the area is reduced to less than 1.8 million sq km (must be in the southern half of the 7th arc).
4. Given #1, #2, and #3, and adding in the EOF data and analysis, the area is reduced by X5 to less than 360 thousand sq km.
5. Finally, given all of the above and adding in the negative search area between ~S35-40, drift analysis and practical navigation limits, the southern half of the 7th arc is reduced from S0-40 degrees to about 5 degrees of arc near S30-S35, or an area of about 45,000 sq km.
That means innovative use of the limited available observations, plus technology, science and engineering, have reduced the area to 0.04% of what we started with on 2014-03-08. Not bad. One more factor of 5-10 and the search could resume.
@ALSM
I can’t find any compelling reason(s) to rule out areas North of 30S.
DennisW:
It was a big picture summary, not a fine scale calculation. You can pick your own 7th arc range, but it is a lot less than S0-S40 degrees now.
@ALSM
Yes, definitely.
@Jeff,
i did not realise this publication. My first observation is that apart from the Reunion flaperon where a qualitative review has been done, no analysis has been done to determine the force and direction of the force that led to failure of the parts.
My second observation (subject to reservation as the quality of the photos is very poor), at first sight, is that it is hard to corelate some of the damage mechanisms with a crash at sea. For instance, the reunion flaperon clearly show crack on the bottom surface of the flaperon consistent with a force excerced from bottom to up on the flaperon rear area (sagging failure). This is unexpected. and very hard to explain in a first place. For Item 9 and 15, despite the poor quality of the photo, it looks like the opposite, the force is coming from the top (hogging failure) which is again unexpected. This is inconsistent with even a roll over scenario as all parts are likely to fail in a logical pattern. If such a crash happens on ground, one could argue some parts can bounce etc but at sea, it is hard to imagine the possibility of this happening without perhaps the aircraft being broken beforehand. If high speed dive led to the aircraft being broken down, the lift force on the flaps would tend to generate a sagging failure for Item 9 and 15 instead. I am sure the high speed dive desintegration could be ruled out by the manufacturer (parts should be designed for normal speed with large enough safety margins, i would be surprised if such parts desintegrate at high speeds due to terminal velocity limits). At first sight it looks like the plane did not crash on contact with the sea or due to high speed dive (??? puzzled ???). I am sure we could learn more about these parts with proper examination and fracture test/modelling. For that part you mentioned @Jeff, it looks like it is a hogging failure type which is totally unexpected and hard to imagine how it could have happened regardless of how the aircraft crash (nose first, high speed in deep dive, belly impact or roll over then impact).
Also, it would be possible to learn from how the fateners and bolt assembly(shear failure or pull up failure) have failed.
For hogging and sagging definition ref to https://en.wikipedia.org/wiki/Hogging_and_sagging
Why do we still talk about failure of the plane? If you ask me someone flew the plane with a level course towards the southpole fully knowing he would crash it somewhere in the southern ocean. He probably thought he could pull off a scully or something as a last heroic statement in his sick mind.
@ralf
It is a very good question. Although I would agree that the most important would be to find the bulk of the plane, since it has not yet been found with the current methods employed and will not because the search has been suspended, in my opinion, vital piece of information could be obtained from the debris which could help us find what has actually happened. I bear in mind that the black box is the best piece of information for that but in the meantime we need to know what has happened based on the existing clues. To analyse a suspected crime scene, the police perform forensics on the body. Not saying it is a crime but the debris can provide hard evidence of what has actually happened. It can also help with the interpretration of other clues including sat data and actual location and whether the search was simply unlucky or the location was wrong. Many would disagree but the debris information could provide in my view the credible information the investigating team needs to resume the search.
Why searching where the inmersat data suggests and not searching where the debris data suggest (i note previous comments saying that area was ruled out for some reasons)? The two set of data have discrepancies that still cannot be understood. Similary, a detailed forensic on the raw radar data will be extremely useful(if the data actually exist and correspond to the plane after it passed IGARI and how it correlate to the witnesses’ account – this information has been confirmed not to be available). If raw radar data cannot be released for national security reason, at least, a detailed report on the analysis of the radar data should be released.
To follow up with the above analogy, the debris are body parts, the radar data are finger prints/foot steps. The inmersat data is analogous to a system tracing where a mobile phone has been – just need to make sure it is the right mobile phone, the right data from the right receiving station and the data is well interpreted. Again my opinion but I would rather rely on the first two than the latter.
All the evidence continues to point to planted debris that were pulled from a plane that landed somewhere intact.
@ALSM
Thanks for the response ALSM. You wrote:
“That said, the end of flight analysis cuts the search area by a factor of 5 from what it might otherwise be (200 nm wide to 40 nm wide).”
That is actually what I had in mind. I wondered if the current debris analysis can confirm or change end-of-flight scenario and redefine (widen or narrow) the current search area along the sevent arc.
Marijan: The state of the debris, especially the flaperon and flap, tends to confirm the rapid descent indicated by BFO and other observations.
RE NLG Doors:
After further research, it appears that loss of hydraulic pressure would not cause the NLG doors to sag or open. Thus, if the right front NLG it did separate in-flight, loss of hydraulic pressure would not have been a contributing factor. Don Thompson did the research. His email summary follows.
The RAT pressurises only part of the centre system, i.e. the PFCS surfaces (one way valve isolates from the major part of centre system pressurised by air driven or AC pumps).
If the RAT destructed, then I’d expect a complete loss of pressure throughout the centre system (one way valve allows all/any pressure to drain via fractured RAT connections)
However, the Nose Landing Gear Selector Bypass Valve controls the pressurised supply into either extend or retract mechanisms. The AMM includes this note:
“The NLG selector/bypass valve automatically removes pressure from the NLG retract lines approximately ten seconds after the gear is up and locked.”
Therefore, when the gear is up, the NLG system is ‘passive’, unpressurised.
Also, the NLG door actuator system comprises locks. See attached, summarises the retract/extend sequence.
Relevant note from the AMM Hydraulics chapter:
“Training Information Point
The minimum airspeed of 115 knots is necessary for the RAT to supply rated capacity.
When the RAT is extended and hydraulics off, the airplane rolls left. Two to three units of right control wheel rotation are necessary to hold the wings level.”
@Dave Tarrant
“All the evidence continues to point to planted debris that were pulled from a plane …”
I agree that the debris evaluation neither agrees with the (sleepy) consensus of un pilot-d high speed impact impact nor deep SIO location. We have been mis-lead by the experts.
@ALSM, Thanks for passing along that info from Don Thompson, that’s extremely interesting.
You’ll see that wrt the flutter issue I’ve appended some additional portions of my interview with the source within the investigation.
@ALSM
“One more factor of 5-10 and the search could resume.”
Here is that factor, I am thinking: Get rid of FMT at 1840 assumption and allow the BFO data to tell us where the crash site actually is. We are missing what BFO is saying.
Quite similar to DrB’s path but a little east 33.5 +-.
Wouldn’t components from QZ8501 & AF447 be able to confirm the suspicion of a mid air break up or high speed dive of Mh370?
Refering to the mention by @Mike “Many of the external surfaces recovered show significant signs of fracture, rivets pulled right through, and this remains consistent with an aircraft exceeding its operational envelope due to overspeed/flutter.”
A lot could be derived from this taking into account the plane manufacturer design limits (as opposed to the operating envelope).
With proper analysis, this should be able to tell us if the engines were powered to achieve those limits or not.
Boeing should be able to confirm whether overspeed could lead to sufficient fluttering and landing gear door damage, the same could be confirmed for the other parts.
In case of the postulated scenario of fuel exhaustion leading to power failure we are talking of a deep dive with a terminal velocity limit (not sure what this is for a B777). I would be surprised (one expert should confirm) if this exceeds the design limit of any part for a B777. If not then the engines must have been ON and we have inconsitency with sat data again as well as the uncontrolled plane scenario.
Is the deep dive terminal velocity sufficient to exceed the DESIGN limit of the landing gear door? If not, then we have inconsitency with the official scenario (not saying we should be consistent).
In any case for the flaps and flaperon it is hard to imagine overpeed due to umpowered deep dive could be a factor and yet the failure of these parts tend to indicate forces directions inconsitencies with impact with sea surface. Unless of course the engines were on with on top of that overpeed.
Note here the overpeed is only possible in case of human error or electronic failure (not sure about mechnical failure). Electronic failure is highly unlikly due to stringent design standards and redundancy but total power failure with engines ON may be a scenario to consider despite redundancy in power supply. It is also hard to conceive a total power failure (without fuel exhaustion) being an extraordinary concurrent malfunction saying that human error would be a more likely cause.
And if the engines were still on …? Could we still rely on the sat data?
@ALSM Are you talking about a scenario of landing door opening in mid air leading to depresurisation and subsequent domino effects leading to unpowered deep dive or mid air desintegration? with power failure as common cause and no one in control of the plane? Is this possible? Can power failure lead to opening of the landing gear door and with a complex domino scenario leading to mid air desintegration of parts?