One of the most misunderstood insights into the riddle of MH370 is how the plane’s final path can be derived from Inmarsat BTO data alone.
Recall that the data, which was generated after someone on board caused the Satellite Data Unit (SDU) to re-logon to the Inmarsat Satellite 3F-1 over the Indian Ocean at 18:25, comes in two flavors. The first, the Burst Timing Offset (BTO) data, reveals how far the plane is from the satellite at a given time. This can be mathematically converted into a set of “ping rings” along which the plane must have been at a given time. The BTO data is very well understood and fairly precise, providing an accuracy of within 10 km.
The second, the Burst Frequency Offset (BFO) data, is more more complicated and much fuzzier than the BTO data; its inherent uncertainties are equivalent to a position error of hundreds of miles. It doesn’t have a single physical correlate but is related to how fast a plane is going, what direction it is headed, and where it is located.
For a time after MH370 disappeared, searchers hoped that they could combine these two data sets to identify the area where the plane issued its final ping. After months of work, however, they determined that this would be impossible. The BFO data is just too vague. However, along with the bad news came some good: it turned out that by the clever use of statistics they could figure out where the plane went using the BTO data alone. The methodology developed by Australia’s Defense Science and Technology Group (DSTG) and explained in an ATSB report entitled “MH370 – Definition of Underwater Search Areas” released last December.
Many independent researchers do not understand the technique and believe that it is invalid. For instance, reader DennisW recently opined that “The ISAT data cannot, by itself, be used to determine a flight path. One has to invoke additional constraints to derive a terminus.” But I believe that the DSTG position is correct, and that one does not need to invoke arbitrary additional assumptions in order to calculate the plane’s track. I’ll explain why.
First, some basics. Imagine that you have two ping rings, one created an hour after the other. For the sake of simplicity, let’s say the rings are concentric, with the later ring’s radius 300 nautical miles bigger than the earlier one’s. Let’s further assume that the plane crossed some arbitrary point on the innermost ring. If that’s all we know, then the plane could have taken any of an infinite number of routes from the first to the second. It could have travelled radially directly outward at 300 knots. Or, if traveling straight at 400 knots, it could have turned left or right at an angle. Or, it could have traveled faster than 300 knots on any number of meandering paths. So, the fact of the matter is that this simple understanding of the plane’s situation indicates that it could have traveled by wide number of paths and speeds to a wide range of points on the second arc.
However, there are some pecularities of commercial aviation that narrow the possibilities considerably. The most important is that planes can only travel in straight lines. They can turn, but in between turns they will fly straight. Knowing this vastly reduces the number of paths that MH370 could have taken between 19:41 and 0:11. It could not of simply meandered around the sky; it must have followed a path of one, two, three, four, or more straight segments.
Through the marvels of modern computing, researchers can generate a huge number of random routes and test them to see which fit the observed data. It turns out that if the plane flew straight in a single segment, the only routes that match the data are those that are fast, around the speed that commercial jets normally fly, and end up over the current search area. If you assume that the flight involved two straight segments, it turns out the ones that fit best are those in which the two segments are nearly in a straight line and are also fast and wind up over the current search area.
If you suppose that the flight after 19:41 involved a larger number of segments, your computer’s random generation process will be able to come up with valid routes that are neither straight nor fast, and do not end up in the current search area. But to come up with such routes, the computer will have to generate many, many others that do not fit. So it is extremely unlikely that by random chance the plane would have happened to travel a slow, curving route that just happened to “look like” a straight, fast route.
“Well,” you might object, “presumably whoever was in control didn’t fly randomly, they had a plan, so modeling by random paths isn’t appropriate.” But a plan of unknown characteristics is equivalent for our purposes to a random one. After all, there is no imaginable reason for someone to fly a plane over empty ocean in the dark at a slower-than-usual rate, making slight turns every hour or so. (Before you say that they might have done it to throw searchers off their trail after the fact, bear in mind that whoever took the plane would have had no way to know that Inmarsat had started logging BTO values a few months before, let alone imagine that they would be able to conduct this kind of analysis.)
When DSTG ran the math, they came up with a probability distribution along the arc that looks like the image at top.
Worth noting that the peak of the curve, and the lion’s share of the area under it, lie in the southern half of the search box, but it also has tails that extend past the box in either direction.
When the search of the seabed began, many expected that the plane would be found in short order. When it wasn’t, the burning question then became: how far out from the 7th arc should we search? A one-dimensional question had now become a two-dimensional one. Based on past loss-of-control accidents and flight simulations, the ATSB decided that an out-of-fuel 777 with no pilot would enter a spiral dive and impact the surface within 20 nautical miles. Mapping the two probability distributions (i.e., where the plane crossed the 7th arc, and where/how far it flew after that) yielded the following probability distribution:
I believe that we have to take the image above with a grain of salt, as I don’t think it is really possible for a plane to fly more than 40 km by itself. It’s generally agreed that the only way the plane could have plausbily gone further than that is if the pilot was conscious and actively holding the plane steady in a glide, in which case it might have gone as far as 100 nm.
A few months before the ATSB publlshed this analysis, a further set of information about the impact point of MH370 became availalble: the plane’s right-hand flaperon washed up on Réunion Island. Reverse-drift analysis was performed by several independent groups to determine where the flaperon might have started its journey. The German institute GEOMAR came up with the following results:
As you can see, the probability distribution hardly overlaps at all with the probability distribution derived from the BTO data; it only touches at the northeastern corner of the search box. Drift analysis performed by other groups reached a similar conclusion. Using a branch of mathematics called Bayesian analysis, it’s possible to take two probability distributions and merge them into a single one. I’m not a mathematician myself, but intuitively one would surmise that given both the BTO and the drift-model data sets, the new peak probability are should lie somewhere between the northern end of the current search box and Broken Ridge.
The ATSB report disagreed, arguing that the drift analysis
… made no meaningful changes to the ATSB search area due to the relative weighting of the significance of the drift analysis in comparison with the analysis based on the satellite data. While this debris find is consistent with the current search area it does not provide sufficient information to refine it.
What this means is that the ATSB considers the BTO data and its analysis “hard” and the reverse-drift analysis “soft,” because the random motion of ocean currents introduces a large amount of uncertainty. However, the reported also noted that “if additional debris is identified it will be included in the analysis to provide further information on the location of source areas.” Indeed, after the report came out other pieces of debris were found, and drift modeling of these pieces be used to refine the search area. Indeed, after I published last week’s guest post by MPat, reader Ge Rijn pointed out:
Over those 20 years in MPat’s model only 7 out of 177 buoys landed in Australia. Those 7 all passed the search box under 36S… [this] points clearly to the trend the more south you go under ~36S the more likely it becomes buoys (debris) will land on Australia and the more north you go above 36S the less likely it becomes buoys~(debris) will land on Australia. This is also because the more south you go under ~36 the currents tend to go further east and the more north you go around 36S the currents tend to bend stronger to the north avoiding Australia. And this is exacly what the facts about found debris shows us till now.
Note that 36 degrees south is just shy of the northern end of the current search area; as Ge Rijn observes, historical drift data suggests that if the plane had crashed south of this latitude, debris should have been found in Australia, which it obviously hasn’t.
The size and species mix of barnacles growing on ocean debris could provide clues as to which waters it floated through; oxygen isotope analysis can provide information about the temperature of the waters that it floated through. As far as I know, no such analyses have been conducted. For a long while now, the ATSB’s weekly update reports have included the phrase “In the absence of credible new information that leads to the identification of a specific location of the aircraft, Governments have agreed that there will be no further expansion of the search area.” The fact is, though, that further information is available, and it could be used to determine which of the two possible explanations is more likely: that the plane passed over the current search area and was held in a glide, or crossed the seventh arc further (but not too much further) to the northeast.
@Ge Rijn
@David
GE Rijn, if I may add my “four pennyworth” here: The ATSB have always said they are handling the search on behalf of the Malaysian government, and that the Malaysians are responsible for the investigation. So I wouldn’t expect the ATSB to be publishing any independent reports.
That’s how I read the situation.
And I think it’s interesting to note the Media are now reporting Fugro as saying they now believe he could have glided well beyond the 7th arc, and consequently they have been looking in the wrong place, all this time!
(incidentally, just what I had been saying for many months, frustrating or what.)
The Fugro comments seem to be timed to coincide with the imminent Tripartite Ministers Meeting, so the comments must be partly political.
@dah ha
I think it’s unavoidable to speculate on the possible role Zaharie could have played in this mystery. And sometimes very speculative statements get made. I do it myself sometimes but never present them as ‘facts’.
You’re absolutly right no one can condemm anyone without proof. And you are right there is absolutely no proof yet on which role Zaharie played.
And I understand statements made can be quite grieving to related people.
But as I say; in the context of the drama it’s unavoidable Zaharie’s possible role gets discussed.
Your post though to me is a reminder to be carefull about how things about Zaharie are stated.
Regardless if you are realy his brother or not.
It would be nice if you can prove that here (or to Jeff Wise) and share your thoughts and knowledge about the case.
@ROB: “reporting Fugro as saying they now believe he could have glided well beyond the 7th arc, …”.
It is not a matter of believing. It is a fact, and always has been, that MH370 could have glided well beyond the 7th arc,
@Gysbreght
Thank you Gysbreght. Nice to see you on the ball. I was only testing to see if you were up yet.
Then they have to explain the partial ping which could only happen if the plane turned upside down.
@Ge Rijn. The flange I mentioned is on the flaperon, exhibits 10 and 13.
I think the ATSB is bound by normal practice if not a specific agreement. There is one investigator, as usual and he has delegated the search function, that’s all. See introduction to the last identification report, ATSB “was requested by the Malaysian Government in the formal identification of the items to determine if they came from…MH370.”
This is most likely why the French investigation has not been disclosed. That does not mean that publication of ATSB findings will not be made public. Identifications at least have been. Who knows what has happened to marine biology and other investigations though.
@David
Thanks for clarifying.
I e-mailed the ATSB with the request to clarify this subject.
If they answer I let all know offcourse.
@Rob
I read todays article too..Here’s a link that.http://www.independent.co.uk/news/world/asia/mh370-search-team-looking-for-missing-malaysia-airlines-flight-reveals-new-theory-on-planes-location-a7147681.html
I wonder what they’ve drawn glide theory from? Has ATSB found something with debris recovered on how mh370 impacted the water? If so are they keeping quite about it.So not to admit they have been searching in the wrong place.
If MH370 did glide. DID the Chinese satellite detect the debris around 36 south. Still pieces would have washed a shore on west coast of australia. Maybe some debris has but no one’s looking? Big stretch of coast line.
@all
My e-mail to the ATSB:
Dear Sir/Madame,
On the blog of Jeff Wise: http://jeffwise.net/category/aviation/ we are currently debating the independent investigation status of the ATSB.
Some of the debaters are convinced the ATSB is not independent for they are bound by agreements made between involved countries about disclosing information to the public.
Now I understand discloser of information has to be done very carefull and in coherence with involved countries and other involved parties and agreements made about this are necessary.
But the opinion stated in the discussion is that the ATSB will not disclose their final report and findings/conclusions if this is not allowed by Malysia, China or the Government of Australia.
My opinion is the ATSB is an independent investigator who has the freedom to come forward with their own (final) reports and can not and will not get forced by any government to keep their findings secret.
Can you please tell me which opinion is the right one?
Sincerely,
Ge Rijn
@All..
Remember the Comores Island boeing 767 crash.. Footage shows the pilot who was controlling the plane as it ran out of fuel (under botched hijacking attempt) tried to glide the plane for a soft impacted.. As you can see the speed of the plane hitting caused the 767 to break apart on impact..Some of you have suggested that some of the debris looks like it could have been a glide impact event…
Here’s youtube link.. Be advised some images which some may find graphical in nature..
https://www.youtube.com/watch?v=zA5FMFVbVZ0
@Ge Rijn. “..findings/conclusions if this is not allowed by Malaysia, China or the Government of Australia.” I do not think China or the Government of Australia come into it but lets see if they respond.
I should add that from the quote in my last, the ATSB was charged with identifying the origin of parts as being from MH370. That is all. The French situation is a little different since the flaperon landed on French soil (though so did others Australia has been given the task of identifying!). My (rhetorical) question is whether Australia has been tasked with a reconstruction of the part-flap separation.
@Rob. Sorry, missed your last post. We say the same, as did Ventus45.
@Gysbreght
I’m glad you explained your interest in that matter, and I will try to explain.
Assuming Shah or anybody else able to fly the 777 manually with great expertise, the hardest part of such a plan would be the time staying undetected. If the turnback wuld be discovered early, lets say already during the turn and some alert would have been raised, the chance to be intercepted would be increased considerably. Therefore the plan had elements like going dark on secondary radar, ACARS and comms and leaving the original planned track, as that would be the first portion of the airspace somebody would be looking for. But the pilot was well aware that he still could be seen on primary radar and he could not exclude that a vigilant military controller would by chance observe not only the loss of secondary radar information, but also the turnback on primary radar. What he could do though is throw the judgement of said controller off by performing the turnback in a way, which would not be asociated with the normal and typical turn of a B777 and thus being overlooked as some false radar indication. The radar controller or even a logic software would disregard such a turn and expect some radar malfunction and a later showup of the target some distance down of the original track.
Break turn.
It is a max performance turn using maximum available bank and loadfactor while controlling the airspeed with power and vertical speed. The aim is to change the track as expeditious as possible, f.e. in an air to air fight to deny an attacker a shooting solution, to outturn a missile shot or to get yourself in a better shooting position. The vertical (descending and climbing or vice verse) is used to reduce the turn radius in relation to the ground track and to decellerate, maintain or increase speed during the maneuver. Caution in advance, I’ve no flying expierience in a 777, so do not nail me on details of the following.
It could have been performed like follows: Manual mode, autothrottle off, advance full power while pulling the nose up (20-30°) and simultaneausly rolling in bank (max achievable, do not know how much the aircraft would allow) into the direction of the turn. This would cause a left climbing turn and despite the power a reduction of TAS. It is important to control the AOA by modulating the loadfactor with the pitch, the bank stays as high as possible. When the speed reduces the climb will cease and the nose controlled by AOA and bank angle will come down through the horizon line, the following descent rate would help to accelerate again, to roll out on the new track and to recover the descent. The altitude excursions would also help to throw off primary radar. Planned and trained on a simulator an expierienced pilot could be able to perfom such a turn in his aircraft.
What could go wrong? He could exceed stall AOA and get out of control, but with 10 km of air beneath him a recovery (unlike AF447) should pose no problem. He would have thrown off any radar controler with that too.
If the pilot of MH370 has planned such an maneuver (or a similar one ) he would have weighed the risk to mess up the maneuver with the risk to get discovered in the early stage of his mission. And turning around unnoticed as long as possible was the key element of hijacking of MH370. Otherwise the pilot could have just turned around with normal secondary radar contact, mumbling some garbeled words to simulate some comunication failure and proceed on to Penang unharmed, as anybody would expect him coming in for landing.
The pilot would have trained the maneuver in the simulator, and he would have had the knowledge to judge how much the aircraft could handle. I see not much risk there for the mission, but gain in vital time unobserved by ATC and military radar and thus an overall plus for the mission. If we accept the details of the routing from IGARI to MEKAR, then it worked pretty well for the culprits.
@Aaron
You raise an interesting point. To me, the evidence always pointed to a carefully pre-planned act by the Captain (nothing really startling there, as it’s also been the most widely held view among those best qualified to comment on the matter, namely the majority of airline crews, worldwide) but the big question for me was: how had he planned to hide the wreckage? The flaperon, and the negative (not a false negative BTW) search results pointed to the answer – he planned a controlled glide.
The ATSB have had to keep stumm, because the Malaysians are calling the shots. A sad fact, but a true one.
Now the chickens are coming home to roost. Fugro obviously want to distance themselves from the mess the ATSB are in, which is quite reasonable.
If the ATSB can find evidence that the outboard flap was lowered when the aircraft hit the water, they might be able to persuade their partners to agree to extending the search downrange. So we really are in the last chance saloon.
@Ge Rijn
I emailed ATSB some time back. They made it clear that its up to Malaysia what gets released and when.
@David
Yes, lets see if they will communicate about this. I expect them to if they leave an open source e-mail contact adress on their site.
I think they are not limited by identification alone. They also stated they were reseaching the bio-fauling and they were/are deeply involved in determinating flightpaths and the current search area.
Determinating how the flap seperated must therefore be an important task for them also for it can be decisive on how and where the plane entered the water; did it glide? Or did it dive?
Crucial to their dedicated task and responsability to find the plane in the most probable area that probably has to be adjusted by them.
The first statements from an official in the search team are allready made (link @Aaron previous post).
And I think that’s telling.
I assume they have allready made some important conclusions regarding the outboard flap section and its seperation.
And I expect a confirmation of the piece and a report on this can be awaited fairly soon.
@AM2
Maybe my question is different than the one(s) you asked?
I ask clarity about their independence.
If other authotities can force them to silence about (crucial) findings and information their independence is non exsistent IMO.
And if they refuse to clarify a question like this they subject themselves to not being independent in this matter anyway IMO.
I expect them not wanting to leave a suggestion like that on an international well read and respected blog as this.
@RetiredF4:
Thanks for the clarification of your position in your last post. I could take issue with some details in your explanation. However, a discussion on that level would go over the heads of the readers of this blog, so I think it is better to refrain from it.
In short, the risks involved in such a manoevre for a transport are greater than you suggest, and the imaginary advantage you are construing do not justify that risk for any rational person familiar with transport airplane limitations and flight dynamics.
@JeffWise
Why is ‘The Spoof’ no longer on the website?
@Gysbreght said, “In short, the risks involved in such a manoevre for a transport are greater than you suggest, and the imaginary advantage you are construing do not justify that risk for any rational person familiar with transport airplane limitations and flight dynamics.”
Months ago, I have asked Ed Baker, a B767 pilot, about this very thing. His comment was a chandelle manoeuver would be easy for an experienced pilot to perform. In fact, I’m told that this manoeuver is part of the requirement for commercial pilot certification in the US, although probably not in all countries. So I strongly disagree with your assertion that this would not have been performed by a “rational person familiar with transport airplane limitations and flight dynamics.”
@Gysbreght, a little bird told me that some professional pilot rumors are waiting in your inbox.
@VictorI: Did you ask ‘Ed Baker’ objective would entice a pilot to perform that manoeuvre on this particular occasion?
Interesting interview on the search:
https://www.facebook.com/skynews/videos/vb.164665060214766/1403603446320915/?type=2&theater
@Jeff, please check your Facebook PMs for a message from me.
@All, the last message from this account at July 20, 2016 at 9:22 PM is yet again another spoof. It’s possible other accounts are (still) compromised too. I have asked Jeff to disable my account. Please ignore anything further coming from this account until Jeff disables as it won’t be “me” speaking. I believe once the spoofer gets comfortable, the posts will become increasingly incendiary to disrupt discussion here (as @Susie Crowe) has observed, sadly at the cost of people’s reputations.
@Ge Rijn,
Thanks so much for the link, great find. Couple of bullet points from the video:
— more debris has been collected than has been reported in the press
— Boeing is being consulted with to determine how the damage sustained by the pieces occurred.
— in order to justify the continuation of the search, they need enough information to say that “x marks the spot” but they don’t have it yet. So one option might be to suspend the search until such specific location can be determined
– the searchers think that the drift analysis is consistent with the current search area.
@Julie, Okay, I’ll do that.
@Gysbreght: Evasion and fun, although the conversation was mostly about the capabilities of the aircraft and the pilot.
Comments by Fugro managers need to be assessed in light of the
fact that Fugro has made a lot of money out of this search.
Therefore such comments cannot be considered in any way unbiased.
https://en.wikipedia.org/wiki/Fugro
@Jeff Wise
You’re welcome. Seems the ATSB is not that reluctant and limited to give some global information at least and also not limited to identifying pieces only. That they not give specific details yet I can understand for the time being.
I hope dearly the outboard flap section comes just in time to make a difference.
I think it’s going to be a key factor.
And hopefully further research with drift analysing by all the experts will find consensus and together with the Inmarsat data and debris analysis will be able to set that ‘X mark area’.
I have the feeling it might all come just in time.
They just cann’t give up now with all the new debris and drift data.
I can imagine and understand they will decide to delay the operation till further conclusive information is available or conclusions can be drawn on the specific area to search further. And maybe that’s a wise thing to do.
When they started they only had the radar and Inmarsat data. No debris and drift data.
IMO it’s allready quite an achievement if it turns out they came this close only with the data they had.
They know they are close. They know giving up now would be not defendable and acceptable.
I’m confident the search will continue even without Malaysia if necessary.
@VictorI
“The bottom line is it may be possible that MH370 flew at low altitudes and at high speeds. Of course, the fuel consumption would have been several times what it would be at high altitude for the same TAS. I suspect that this was the reasoning behind the shift of the search to the north.”
Does this again open the possibility that the eyewitnesses near Kelantan actually saw MH370 around 17:36?
Those eyewitness accounts always seemed the most credible to me as their locations were directly under the radar track- which was disclosed only sometime after the reports were filed.
https://www.reddit.com/r/MH370/comments/353rms/1736_evidence_of_descent/
@RetF4
If such a maneuver happened at IGARI, it may have also been designed surprise and neutralize any potential threat from the cabin.
For those interested, the “Chandelle” manoeuvre is described in https://en.wikipedia.org/wiki/Chandelle.
It is a far cry from the “break turn” described by RetiredF4 and doesn’t come near to explaining the sharp hook depicted in the ATSB’s presentation of the radar data. The FAA indeed requires it in the curriculum for Commercial Pilot Licence, Single-engine Land and Single-engine Sea. The objectives are stated below.
Note that it is practiced and examined in light general-aviation airplanes used for pilot training.
Here’s a link to a slightly revised version of my aggregate drift study:
https://drive.google.com/file/d/0B-r3yuaF2p72amVHVncxbWxSZEU/view?usp=sharing
2 changes; neither affects any of the observations, conclusions, or recommendations.
The interesting one: due to a reader request, I’ve added 7 test cells south of Sumatra to Slides 2, 18-25, and 40-41.
The technical one: Slides 40-41 (sensitivity testing) were revised to fix an “average of worst” error. In the pdf released June 30, this correction had already been made to all slides in the main deck; this revised pdf merely catches slides 40-41 up:
(warning: hard-core geekery follows)
My original ranking tie-breaker (last term in below formula) was part of query “Method1 by Item Make”:
WProb: Sum([probability]*[Weight]*[PWeight])+0*([SLat]+[SLon]+[PProb]+[DProb])/1000000
It only works if all finds have a unique coordinate; the 3 Madagascar finds all have the same coordinate. I addressed this by zeroing out the deficient method (as above), and replaced it with a new query “Method1 Rank prep” (below), added as a last step in the database’s lone macro:
UPDATE [Method1 by Item] INNER JOIN Debris ON ([Method1 by Item].Item = Debris.Item) AND ([Method1 by Item].Finder = Debris.Finder) SET [Method1 by Item].WProb = [WProb]+Rnd([Index])/10000000;
I’m providing the detailed code in case anyone is trying to replicate my results using the Access database I also posted online. I’m trying to be as transparent as possible, to ensure all my claims are well-supported by verifiable mathematics.
@orion
Your link referres to a post from @oriondt.
The person who posted here before.
Are you the same guy?
@Victor: Martin Dolan told me explicitly that the search moved north despite – not because of, DESPITE – the increased fuel burn.
And AMSA attributed this alleged extra burn to increased speed – not altitude swings, SPEED – in the Malacca Strait.
So I’m afraid your latest theory is on tenuous footing.
Any suggestion the top brass just misspoke (the “Tony Abbott” defense) will simply underscore the need for a stiff audit of all data upon which search decisions were based. We can’t be confident the search was conducted in good faith if the top brass were saying one thing, and the experts were doing quite another.
http://www.skybrary.aero/index.php/B772
Very crudely stated, the “initial descent” phase after cruise occurs at M0.75 / 300KIAS to FL240. Another source states M0.717 / 272KIAS.
IF there actually really was a landing attempt at/near WITT/WITN, THEN perhaps the A/C decelerated to M0.75 / 300KIAS @ FL240. I think that translates into ~420kts TAS.
?
Further thoughts:
Super-fast flight after IGARI implies that the aircraft was structurally sound… the fuselage was not “disintegrating” at IGARI or prior to MEKAR-NILAM, or else no pilot would dare risk flying their plane apart high in the sky. Likewise, super-fast flight precludes the possibility of (severe) inboard fire, which would weaken the airframe. Possibly, there was an outboard wing/engine fire, but no (severe) inboard fire, or the super-fast flight after IGARI would have broken the plane apart.
Thrust setting may have been full forward maximum ?
@Orion: Low altitude (i.e., below 10,000 ft) and high speed (i.e., >480 kt) translates to high dynamic pressures and the potential for flutter and structural damage. I don’t know what the ultimate limits are for a B777. I do think, however, that there is sufficient engine thrust to achieve the high speeds. So for the time being, I think we need to leave that possibility on the table.
@Brock McEwen: You are trying to draw definitive conclusions from imprecise statements. This leads the opening to your interpretation that search is a farce.
And yes, if the plane flew at very high indicated airspeeds, the plane would have burned more fuel. This would occur if the plane reached high true airspeeds at low altitudes. The AMSA statement could have been accurate.
@Victor: you make my point. If everything this alphabet soup of search agencies has ever said can be taken to mean either “A” or “not A” – depending on what we need to support our theory du jour – then what does that tell us about search transparency? Accountability? Quality? The need for a stiff and comprehensive audit?
Attempts to imply AMSA/ATSB/Abbott’s foray up to 21s isn’t worth rigorously auditing appear, to me, absurd. The gaps between the decisions they took and what their own data could support are a matter of public record. They drew a line across Arc 7 – a point well SW of 21s – PRIOR to subtracting fuel, and claimed there was no point searching NE of it, because the plane already lacked the fuel to fly that SLOWLY for 7 hours. Then they took away fuel. I have proven that, IF their performance limit was accurately drawn, THEN taking away fuel actually retracts the achievable portion of Arc 7 in BOTH directions (SW limit moves NE, yes, but NE limit also moves SW). This last point is unassailable, so part of your argument must be that the ATSB drew their March 17-27 performance limit incorrectly.
And that’s BEFORE any consideration of their acoustic ping “analysis”…
* * *
Any progress on the precise sample path which disproves Dr. Bobby Ulich’s conclusion about cruising altitude being required between IGARI and the 18:22 fix? I assumed you had one lying around; the plausibility of any such path is a critical differentiator between the two theories you consider still on the table.
I’m not doubting your understanding of B777 performance limits. Just trying to definitively eliminate one source of ambiguity – one gap between what two experts have said.
@Gysbreght
Few comments on the Chandelle and the relevance to the possible maneuver at IGARI
Maneuvers with a nametag on it are basic maneuvers for training. The next step is combining maneuvers to a sequence of maneuvers, while this sequence is dependent on the required outcome. One example would be an airshow. In a later advanced stage maneuvers and parts of different maneuvers are combined again to a sequence, the difference being that not the exact completion of the individual maneuver is the goal, but the sequence serves the intention to either act offensive or defensive.
I could describe the individual parts of training maneuvers from which the described break turn is derived, but an average student fighter pilot in flying training needs quite some training to get the required combinations right, which makes the difference between win or loose the fight. Either you give my thoughts some merit or you object them, like you do at the moment.
Additionally I like to add that I was not in the aircraft and know no more than you do, it is just speculation on my side, although an imho educated one.
The easy way out to explain the hook turn at IGARI is bad information, bad radar data, faked radar track and so on. It is not my path of thinking.
@Brock McEwen: Frankly, I can’t follow your logic. I am lost in the jumble of speed, altitude, fuel burn, and actions performed before and after the FMT. You say you want an audit of search decisions because of this confusion. My feeling is it would be a waste of time trying to retread past decisions which might have been based on false assumptions. Then again, I have more faith that the search is well-intentioned, so I think time and effort is better placed in other directions.
The requirement for cruise altitudes between IGARI and 18:22 is based on fuel efficiency. I believe the plane could have flown lower and burned more fuel at a higher IAS and at about the same TAS for parts of the flight. As I said previously, the main limitation would be structural limits at high IAS. Onset of flutter data sets probably exist. I am not sure ultimate failure data sets exist for high IAS conditions.
It sounds like maybe mh370 tried to avoid collision with another unexpected aircraft between IGARI and BITOD if there was a dive then altitudes restoration with hook path.
@RetiredF4:
I’m truly grateful for the time and patience you are affording to my views. Your operational experience could be a valuable complement to my more analytical approach.
Your reference seems to be the ATSB’s rendering of the radar data, published in the first ATSB report of August, 2014. For two reasons the rendering of the initial turn after IGARI in that graph is unlikely to represent the actual path of the airplane. The first is the improbable ‘hook’. The other is the timing discrepancy that Victor Iannello has highlighted earlier.
In some respects the path based on the speed and track data in Figure 4.2 of the DSTG “Bayesian Methods” report is probably a more truthful representation of the main dimensions of that path. However, due to the excessive filtering and smoothing that the DSTG has applied to the raw radar data, the ‘DSTG’ path is deficient on details. For example, the DSTG-based path begins to deviate from the assigned route well before the time of the “Good night” of the pilot at 17:19:30 and the reported time over IGARI at 17:20:31.
@RetiredF4
do you mean something like Tex Johnson’s 707 “lag displacement roll”?
…he was simply selling the airplane;
https://www.youtube.com/watch?v=Ra_khhzuFlE
@VictorI: “Onset of flutter data sets probably exist. I am not sure ultimate failure data sets exist for high IAS conditions.”
Under the caveat that flutter is not an area in which I have particular expertise, my understanding is that aeroelastic instability boundaries are defined by TAS rather than IAS.
Is there any factual evidence that the airplane descended to low altitudes before 18:22?
@Victor: no, the concern – explicitly stated in this forum, by Jeff and others – was that, if the plane performed “wild altitude swings” between the two points, then average ground speed would inevitably need to be sacrificed – which would contradict the radar fix at 18:22. Period. Fuel efficiency/range implications never entered into it.
I am determined to force the SSWG and its agencies to fully account for all search decisions taken – to pull apart the “jumble of speed, altitude, fuel burn, and actions performed before and after the (alleged) FMT”, and find out exactly how these decisions were made – to determine with certainty precisely “who knew what when”. I firmly believe closure for the families requires this critical step, whether the search has been in good faith or not. I will do it with your help if I can, and without your help if I must.
@dah ah
excuse all my posts over time too, but I still firmly believe that everything he did was with some very good intents; question is when and if it will be known at all
In this paper, the flutter criteria is based on dynamic pressure and Mach number.
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000037720.pdf
I am not aware of definitive evidence that the aircraft descended to low altitudes before 18:22. But the intermittent radar signal and the cell phone connect near Penang are consistent with low altitudes at least for portions of the flight.
I know you believe that the SIO coordinates found on the pilot’s computer and the cell phone connect near Penang are unsubstantiated rumors. For a number of reasons, including reasons I cannot disclose publicly, I believe that both are true. We’ll have to wait for more evidence to become public.
@Brock McEwen: Look at the speed profile in Figure 4.2 of the DSTG report. You will see a big dip at IGARI, some very high speeds with some speed variation, and the plane still reaches the 18:22 radar point (actually 18:02). As best as I can tell, there is nothing about this speed curve (other than flutter due to overspeed) that precludes a low altitude for portions of this path, including the portion near Penang where the radar signal was lost as per the FI. There would be higher fuel burn at low altitude, however.
I don’t know how to better explain this.
@Gysbreght: One last item regarding evidence of low altitude before 18:02. From The DSTG report page 19:
In addition, the ground speed observed by the radar prior to 18:02 is relatively high and implies that the aircraft would have been at low altitude. This is likely to result in poor fuel efficiency, and in order to maintain flight for the duration indicated by the satellite data, the aircraft would have had to slow and increase altitude at some stage to conserve fuel. This is also consistent with a potential speed change between 18:02 and 18:22.
@VictorI
Thank you.
@Ge Rijn
Yes indeed.