[Editor’s note: One of the most intriguing clues in the MH370 mystery is the fact that the airplane’s satcom system logged back on to the Inmarsat network at 18:25. By understanding how such an event could take place, we can significantly narrow the range of possible narratives. In the interest of getting everyone on the same page in understanding this event, I’ve asked Mike Exner for permission to post the content of a detailed comment he recently provided. One piece of background: a lot of us have been referring to the satellite communications system aboard the aircraft as the “SDU,” but as Mike recently pointed out in another comment, it technically should be called the “AES.” — JW.]
Until we have more evidence to support the theory that the loss of AES communications was due to the loss of primary power to the AES, we must keep an open mind. Loss of power may be the most likely cause (simplest explanation), but the fact is we do not know why the sat link was down between 17:37 and 18:25. My reluctance to jump to the conclusion that it must have been due to the loss of primary AES power is based on decades of experience in the MSS (mobile satellite service) industry. It’s not just another opinion based on convenience to support a theory. Let me elaborate on a few possible alternative explanations.
The potential for loss of the pilot carrier, due to the orientation of the aircraft in relation to the satellite, was increased as soon as the airplane turned WNW. Between the time of this turn (circa 17:50) and the time of the FMT (final major turn circa 18:25-18:40), the aircraft was flying more or less toward the satellite where the antenna pattern was near a null. Don and I have both looked at the antenna pattern in some detail and concluded that the antenna pattern and coincidental direction of flight were unlikely to be so bad that the pilot carrier would be lost due to this geometry. Moreover, according to a MAS Press Conference on March 20, 2014, there should have been an ACARS message transmitted at 17:37, but none was received. ( bit.ly/QFbF6C ) At 17:37, the aircraft was still over Malaysia SW bound, so the HGA pattern would not have been an issue at that point. Taken together, loss of the pilot carrier due to antenna orientation appears to be a possible, but unlikely explanation for the outage.
Ionospheric scintillation has also been suggested as a possible explanation for the loss of service during this period, but there have been no reports of other aircraft in the vicinity suffering a loss of service, so this explanation is also unlikely. (Note: Ionospheric scintillation in the equatorial regions can be a big problem for VHF and UHF communications, but it does not affect communications in the L band as much.)
The MCS6000 AES, located in the back of the airplane, requires a continuous feed of INS data (position, speed, etc.) via an ARINC 429 link from the computers in the front of the plane. If the AES stopped receiving INS data for any reason, then it would not have been able to steer the HGA, or compute the required Doppler corrected transmitter frequency. Thus, it is very likely that the AES would be out of service if there was any loss of this 429 data link, or the information carried over the link. Given that there was no VHF voice communications after 17:19:24 and the Transponder Mode S data was lost after 17:21:13, it is certainly possible that the INS data flowing to the AES was disrupted due to a common failure in some piece of equipment in the E-Bay. This explanation for the loss of service cannot be dismissed as easily as the two previous theories.
However, there is one additional observation that tends to favor the loss of primary power theory over the loss of INS data theory (or the other two theories above). We note that when the AES logged on at 18:25:26, the BFO values for the first few minutes thereafter appear to have been drifting in a way that is more consistent with a restoration of primary power event than a restoration of INS data event. If the AES power had been on during the outage, the oven controlled reference oscillator would have maintained a stable frequency and there should not have been any significant BFO transients following the 18:25:26 logon.
In summary, there are multiple alternative explanations for the AES outage, but loss of primary power is the most likely explanation. Like so many other necessary assumptions, like the mode of navigation after the FMT, we have no choice. We must base the search on the most likely assumptions while maintaining an awareness that few of the assumptions have probabilities of .999.
@Flitzer
My preference relative to terminology is “assumed” it is both neutral and more descriptive of the origin.
As far as debris is concerned, I don’t know of any being found, and I have no suggestions relative to where to look. In simple terms that even an MBA can understand – I don’t know.
@Matty – I find it interesting, though not necessarily relevant, that the search equipment supposedly has the accuracy to find a beer can.
Except that it hasn’t actually found any beer cans, as far as we’ve heard. Or shipping containers or any other sunken debris.
It’s striking to me that even in the SIO, they’ve found neither trash nor treasure, nor are there any recent reports of any floating debris of any kind.
Again, this isn’t necessarily relevant, because maybe they simply aren’t reporting the amount of trash they’re finding, or maybe it’s simply not a place where beer cans end up. But part of me thinks they should pull an old 707 fuselage out of Mojave and sink it just to see if this effort is worthwhile.
Brock,
With re yours: “I will continue to berate anyone who berates the IG for their [s38, e89] estimate”.
I do ‘berate’ s38, e89 estimate. Why? Because it is an outcome of a single hypothesis, which appears to conflict with the logic. There is no problem with the estimate itself. There is a problem with the hypothesis. A number of ‘facts’ that do not fit this hypothesis are currently considered as false or inaccurate, and thus discarded. A simple element is FMT assumption within AP hypothesis. If your replace FMT with some more complex trajectory 18:25-19:41, it may still be able to fit BTO & BFO data sufficiently accurately. But the terminal point would shift towards the Broken Ridge.
In summary, “s38, e89” estimate is valid, but it is certainly not unique.
Don,
Thank you. Now the locations of antennas are clear. The fact that VHF and HF are accessible only from the flight deck might be game changer.
Where is the location of E-Bay? Isn’t it just above the front chassis bay?
JS – In the beginning I was assuming that they would be picking through assorted junk down there, but no mention. I’m curious about the initial survey as larger bits of wreckage should reflect something? Plenty of wreck hunters out there are not working with anything that sensitive. There were the “58 hard objects” they got enthusiastic about early on and since then nothing reported. Reading between the lines, Angus Houston and elsewhere, my feeling atm is that optimism is waning at ATSB. Maybe they started turning up loads of hard objects and realized it was meaningless?
Do you need a beer can detector to spot a fuselage? My ‘guess’ is no. Having said that I reckon the fuselage will be in a lot of pieces. Can anyone help?
The tail end of the fuselage is quite often the only easily identifiable bit left? But it’s a decent lump of metal too. A good experiment would be bathy survey at depth on items the size of engines etc. Wreck hunters operate by distinguishing metal from rock – it’s inexact at times depending on the rock but it gives them the means to operate. Is it noteworthy that the survey was wound up without any fanfare?
@JS / Matty
I would be seriously surprised if they could see a beer can with the sidescan sonar.
From what I know of these systems, the data quality is often not spectacular. To cover the acreage they will probably be running at a low frequency, which typically gives a range of say 500m either side of the tow fish (i.e. a 1km strip) but a relatively low resolution (say 5-10m at the edges of the strip). If something of interest is identified they will have to move up close and shift to a higher frequency (shorter range but higher resolution) to get decent images.
i believe it is quite a trick managing the position of the tool at the end of several kilometres of cable, so getting consistent overlaps of the tracks is probably quite a headache, and issues with terrain following, or ship heave can also create noise in the data. Sea state looks pretty poor at the moment for example if recent videos are anything to go by.
I’d be really curious to see what the sea bed surface looks like, and understand how difficult it might be to resolve small objects against the background. As you say I suspect their best chance is with the engines and landing gear which you might also expect to have drifted less on their descent to the sea floor, so potentially be better grouped.
I’m quite surprised we have not seen even a single image to date. It would not hurt for them to be more open about the difficulties they are facing.
M Pat – the beer can thing was claimed by the search company themself and I have no idea of it’s veracity. They did say detect as opposed to ‘see’ however. Can it distinguish such small bits of aluminium at 1km? I’m still trying to find out.
When JACC released the image from Go Phoenix a while ago, I overlaid the debris field AF447 over it for a scaled comparison:
https://www.dropbox.com/s/h6zh42cp1cr5gdz/Go_Phoenix_SAS_af447.png?dl=0
It surprised me just how difficult it might be to recognize the wreckage.
@Orion – one theory is when mh370 crashed into the SIO the impact didn’t cause airframe disintegration so how would the overlay look in this case?
@orion
With the lack of debris, not so mush as a seat cushion, nor other extraneous items, she sank almost intact. While having a HUGE signature, she will be damn near impossible to find. One has to remember when considering the Air French flight…..even when having compass and bearing it took nearly two years of recovery efforts. MH370 is entirely different, sideways & mind-blowing than the IG & group can ever expect to ponder.
Not wanting to be a doubting Thomas, just want to say, the science, improvements regarding MH370 will be impressive. Especially in regards to the location & “constant contact” innovations yet to come, or one would hope so.
Chris – To sink intact then someone was in control to the end and pulled off a miraculous belly. And it would be sitting there like a shipwreck, they wrecks show up unexpectedly on bathy surveys quite frequently? We need an expert here.
Matty- She has to be nearly intact, belly landing & controlled. The lack of debris proves it. No one wants to believe it, nor accept it, but he, Shah did it. The BTO & BFO data “Land of Oz” math will continue to perplex & probe the minds of the AG & Group to no end.
Matty
Meant IG, not Ag.
No one has significantly explained why one could not pop the CB’s that control the AIMS system from the cockpit. Four 50 amp cb’s with one 25 amp for the maintenance w/o all of the James Bond hacking wack-ah-doodle BS.
@chris – with af447 there was surface debris to help approx the location. With MH370 no debris found in SIO but if sunk and with the ocean currents in SIO it should have spread out abit and picked up by those ships.
With the idea it was a controlled ocean landing I can’t believe it was done until fuel exhaustion as the randomness of how the aircraft hit the ocean sure would make a surface debris field. Which means the impact location is more north.
Still as the noted upon take off the engines were under performing so I don’t see it making as far
@Matty
Consider this…..227 pax, 12 crew. Why…. not a single peep from the a/c?, nor cell phone calls? IGARI was the way point of commitment. The lack of cell phone communications proves it.
@Matty
Randomness is key & planned.
Confront the fears of a closely conspired suicide is as confounding as the source.
Chris – I’ve kept the hacking wackadoodle BS in the fire because it’s not enough to disappear the thing, that’s easy. You would need to create the impression that it crashed because if you fly off radar heading towards the Mid East with 8 hours of fuel with no emergency beacon, no distress signal, and no wreckage there would be widespread and reasonable suspicion it landed.
Matty- It landed w/ all on board…..dead, be it the SIO or otherwise. Shah planned & executed one of the worst AC who dunnits in history. He also got away with it it. Until we prove it otherwise, he’s flown into history & exactly where he wants to be.
@Mtron
IMO the flight went down due to a suicide.
@ orion, thanks very much, not sure how I missed that. (Your earlier overlay plot was excellent too, keep them coming!)
I am no expert, but looks like the GO Phoenix is using the gold standard in side scan (ProSAS), with low frequency / long range / high resolution using synthetic aperture technology. Quoted range 1500m either side of the tow fish, therefore a 3km swathe with sub-metre resolution all the way. The pixel size in their image looks larger than this, but could be an artefact of the image file itself. There are certainly plenty of metre scale returns even in what appears to be a relatively benign sea floor area.
The few detailed bathymetry maps JACC have shared have I think a 100m base lateral resolution, and typically show a lot of vertical relief, even at distances 350 km south west of Broken Ridge. Not trivial to tow the sonar at 150m above seabed, or presumably to resolve small objects. It would be very interesting to see more side scan images.
Also looks like the Fugro vessels have poorer side scan spec, something that was picked up in recent media reports. The standard kit (Edgetech 4200) won’t cut it depth-wise. It looks like they may have loaded out the Edgetech deep tow system instead (2400), and this seems to appear in the video JACC released to MH370 families in November 2014. Best range is 600m to the side, with resolution only 8 metres at a distance of 500m. Swathe is thus only one third of the Phoenix track, so will need 3 times the number of passes to cover the same area. And I don’t think this means an 8 metre object would be easily identifiable, it would presumably just be a single bright pixel, potentially in a background with other bright pixels.
As has been repeatedly stated, this is a very challenging search.
Don,
A few more questions in addition to the previous ones.
– What is the arrangement of wiring for engine control from the flight deck just behind it (e.g. top, bottom, via E-bay)?
– Where is the location of FMC?
– What do engines do in case if the loss of control signals from FMS/flight deck?
Myron, Chris Butler
As mikechillit pointed out, an intact B777 is roughly the size of the North arrow in the JACC image. In my opinion, if there were somebody alive at the controls for a ditching, then due to glide possibilities, the aircraft is not anywhere near the search area.
M Pat, Thanks!
Matty-Perth,
If the perp had no knowledge of the sat data, then somebody made it look exactly as you describe: An airliner with hours of fuel remaining leaves a radar trace pointing down a major air route to the Mid East.
If we had no knowledge of the sat data, this would be a truly frightening scenario.
Orion,
Thanks for creating that scaled composite image of the AFF447 debris field vs the sIO seabed image. It’s something I’ve had on a to-do list (together with an sIO comparison to AF447 sonar/AUV scan areas & QZ8501 areas of interest). It’s incredibly useful to relate the scale of the challenge.
Oleksandr,
B777 avionics are predominantly located in the MEC or EE Bay. That is under the flightdeck, forward of the cargo hold.
The FMC is software executing on the AIMS platform. It’s not a discrete avionics ‘black box’.
Engines: I believe the failsafe is ‘maintain state’. An example, the QF32 turbine disintegration on climb out of Singapore: the final problem after landing involved shutting down #1 engine.
:Don
@chris – [REDACTED — erroneous information removed. The last known radio call from MH370 was “Goodnight, Malaysia 370.”]
[REDACTED] Myron, do not promulgate spurious information here or you will be banned.
@Orion
With all of the grateful testimony coming from the IG & others such as Jeff, Micheal X, and the rest. I sorry to say that the 7th pattern is off. My bet is mid-point between Australia & Diego Garcia.
@ Matty
“You would need to create the impression that it crashed because if you fly off radar heading towards the Mid East with 8 hours of fuel with no emergency beacon, no distress signal, and no wreckage there would be widespread and reasonable suspicion it landed”
I wondered about that, but I’m not so sure anymore. If the plane had gone completely dark near BITOD and stayed that way, assumption would be crash close to last point of contact, fruitless search would ensue taking many weeks. Primary radar trace across Malaysian peninsula may or may not emerge and even if it did, assumption might move to crash somewhere west of the peninsula, another fruitless search ensues. Without a spoof would the degree of suspicion about a nebulous western landing destination be any larger than it is now? The spoof risks more as unless it is absolutely perfect, it would clearly signal foul play.
@M Pat
It would be relatively easy to create a perfect spoof with a decoy aircraft that logged on West of the Malay Peninsula (as was observed), while putting MH370 in the dark. Any slight mismatch in BFO offset would get attributed to retrace, as it has been.
The decoy flies on in whatever direction is selected for a time corresponding to the fuel capacity of MH370, and goes dark or mimics a second login request and goes dark. Can’t get much more perfect than that.
I am not advocating this scenario mind you. Just sayin’. It would be a masterful deception.
Hi Dennis,
Its a staggering amount of trouble to go to when you might as well not bother, and still end up with a similar result.
I would concede however that if a spoof were perpetrated (albeit incredibly unlikely) it would probably have to be along the lines you suggest. Hard enough to imagine a spoofer correctly factoring fuel endurance, and the final partial handshake, but impossible to imagine them correctly accounting for the eclipse effect on the satellite oscillator (for my tiny mind anyway). A real aircraft moving on the appropriate path would be inferred.
The decoy is a real aircraft. No need to account for the eclipse or anything else. It comes along for the ride. The only impediment I see is getting a relatively close match to the initial BFO offset. The BTO values are “memoryless”.
@M Pat Dennisw Matt Perth
There was a dicussion about a decoy drone back in october and it was suggested that a TU160 drone might do. Dont forget, that the perp must know the correct bias, to logon to the satellite under the forged ID of 9M MRO.
I dont know whether it is easy and such a flight would produce the known data, but might be worth to crunch with this scenario?
But it still is puzzling. Logic says to me, if the AES primary power was off for at least 20 minutes as Airlandseaman suggested, then its quite obvious that the effort was intentionally directed to cut the satcommunication. It would not make any sense for a perpetrator to cut the primary power to AES only to re establish it after 18:25h. (By the way : this is the reason for me to dismiss any pilot suicide theories). It seems sound to say that the logon 18:25 did not serve any purpose on 9M MRO. If such a conclusion is established, it might be discussed if a kind of spoof did take place.
After the last detoriation of NATO and russia relationships it comes out, that Jeff Wise hit the right topics in his narrative.
@cosmic
Yes, I was involved in the October discussion, and discussions even earlier than that. The TU160 was suggested because it has a sufficient range and the altitude and speed capability to pull it off (get to the SIO and return to a base). Like you say, the BFO offset (bias) is the only thing that would be a bit tricky, but certainly not the least bit insurmountable.
Jeff certainly put the forensic meat on the bones relative to the whole spoof scenario.
Still, I find it incredibly difficult to believe that anyone could have even anticipated that the Inmarsat data might be used in the manner it has been. That remains a bit of a disconnect for me.
I have trouble with the suicide theory as well, for the reasons you state, and for many other small details that in aggregate work against it.
Don,
Thanks again. With regard to the engines – this is exactly what I expected to hear. It would probably be something similar to AT mode, right?
What I am thinking is the in-flight burst of the nose landing gear tire due to overheating/fire during takeoff. Tire fire hypothesis was circulating for a while, but I am not sure if anyone previously linked it to EE-bay. In the photo you provided, it appears that EE-bay is located just above the compartment accommodating the nose landing gear. Based on your diagram, I would expect coaxial cables for L-VHF, C-VHF and HF placed along the upper centerline of the fuselage, directly connecting respective antennas to the flight deck. During a hypothetical blast of the tire, a piece of rubber or metal debris could punch the fuselage and cut these cables at a time, somewhere just behind the flight deck. If R-VHF coaxial cable is placed along the belly, I would expect it to be affected by likely following fire/heat in EE-Bay. Does this explanation of why all the communication means went down simultaneously make sense?
The turn westward at Penang has a logical explanation in such a case.
Besides the well-known Concorde, a couple of other accidents involving tire fire:
en.wikipedia.org/wiki/Nigeria_Airways_Flight_2120
en.wikipedia.org/wiki/Mexicana_Flight_940
M pat – Dennis – CosmicAcademy
I tend to disagree. Going dark and then disappearing just makes it look very strange. As it is it looks deliberate and if you subtracted the signal data what would be the conclusion? Intentionally diverted, plenty of fuel, no evidence of a crash. The signal data is the only means you have to create the impression it did crash, and any electronic trace left behind was always going to get an exhaustive forensic treatment – fully anticipated. Those Tu 160’s have been bobbing up for sure.
@{DennisW,Matty-Perth,MPat,Cosmic}
The 2nd, 3rd and last (+ one before last) sections in the following post deal with the topic you are discussing:
plus.google.com/102683253990040028382/posts/5b6B7afFk5z
@Oleksandr, such incidents tend to bring the plane down in short order.
@Oleksandr
That fire scenario makes perfect sense,
Thank you !!
Myron
Correction – I’m thinking of Tu 95
Oleksandr, Myron:
A fire that left the avionics systems intact, such that MH370 was able to FLY (presumably for roughly 7 hours), TURN at waypoints (that SOMEONE had to input) and it also appears, NAVIGATE along FIRS.
Please explain out how all that happened.
DennisW:
“I find it incredibly difficult to believe that anyone could have even anticipated that the Inmarsat data might be used in the manner it has been. That remains a bit of a disconnect for me.”
This was touched upon earlier, but went by the wayside.
The perp(s) wouldn’t need to anticipate Inmarsat’s data if they had help – from inside. Either a human being or via a hack.
Jeff,
Small correction: tend->tended. B777 is highly sophisticated and reliable aircraft. I would certainly agree with you if it was about the main landing gear (a total of 12 tires), which are close to the fuel tanks, pipes, etc. But with regard to the nose landing gear, inferno is ‘unlikely’. There are only 2 tires. Depressurized cabin, smog, and burnt/cut cables, particularly in the EE-Bay, which is just above – I would expect this sort of troubles.
I would like to hear more specific arguments why (and how) such an event would bring the plane down in short order.
Recall Flight 192 (B737-800) from KLIA to Bangalore on 2014-04-21. The burst of one tire during takeoff. Did it crash? No. Now recall Air France 4590 (Concorde). Also tire burst. Immediate crash, no survivors.
Right now I am interested whether such an event can bring down all the communication means nearly simultaneously. Divide and conquer.
@Nihonmama
Good catch. I do recall the “inside help” modifier now that you bring it up, but I had completely forgotten it.
Nihonmama,
Just to make it clear, I consider several versions, and “technical failure” is among them due to a number of reasons.
With regard to your questions:
Q: A fire that left the avionics systems intact, such that MH370 was able to FLY (presumably for roughly 7 hours)
A: I am talking about isolated fire just under EE-Bay. And possibly tire burst that damaged some electronics, in particular communication, and depressurized cabin. It appears that this area is the most vulnerable in terms of the communication wires. Imagine there was no cabin fire, there was no cargo fire, there was no engine fire, and all the fuel tanks were intact. Why wouldn’t it fly?
Q: TURN at waypoints (that SOMEONE had to input) and it also appears,
A: So-far I did no see sufficient evidence that MH370 followed any WPs. Close to VAMPI and MEKAR, but that is all. Probably NILAM as it was heading towards it. It could be coincidence – there are many WPs. On the other hand, the crew could be busy with solving other problems, such as re-launching AES. With regard to the turn in question: ATSB’s report does not show it. Either ATSB showed a scheme instead of the actual radar track, or Malaysians did not connect two datasets properly in the Lido image.
Q: NAVIGATE along FIRS.
A: It is also questionable. MH370 did not accurately follow FIR boundary when it was in the Gulf of Thailand. It just happens that the shortest path back to KLIA or Penang airport (these have long runways) avoiding mountains approximately coincides with the FIR boundary. With regard to Malacca: again, it could be either coincidental, or a result of the moving towards some waypoint starting from Penang.
@Oleksandr
Technical failure??
There is nothing to support any theory that is not based on a deliberate diversion. Hard to understand what you could possibly be thinking with this nonsense.
Meanwhile, what would be the obvious reasons for the investigation to go this quiet? Why no apparent interest from western powers still?
Dennis – The decoy flight to the SIO might make more sense than a spoof, especially if Russia was implicated? The Tu 95 would also have the legs and the range to mimic a 777 well enough? Remarkable top speed for a turbo prop and they are bobbing up all over the place as Putin tests everyone’s nerves and defences.
@DennisW
If a spoof scenario is considered with a second plane used, we have no clue whatsoever how long 9M MRO stayed in the air. Maybe for the length of radar documentation, if reliable. So mechanical failure would be possible again, but dont ask me, why there was a spoof then.
@airlandseaman @ron
maybe you got some documentation of the wiring of the circuitry for power supply of the AES?
I am a bit confused that so many people are around the place who insist, that the primary power to the AES will be off. if the left AC Bus is simply shut down.
From what was in the open domain from INMARSAT and JACC it was explicitly said that it is very difficult at all to shut down the primary power to the AES. IT was explained that the power connection cable for the AES starts from an automatic switching system between left and right AC bus. The default position is the left AC Bus. Therefore people say that the AES is powered by the left bus. But this is incorrect. If the left bus is shut down there will be an automatic switch to the right bus. The AES will be able to bridge the timespan until the switching is finished without interruption. This automatic switching system has to be disabled first by pulling the respective Circuit Break. Only after the switching process is disabled, the shut down of the left AC bus will also interrupt the power supply for the AES.
It was said that this includes deep engineering knowledge and pilots are not trained to be capable of doing this.
Am I wrong?
Dennis,
On contrary, there are many things that support technical failure scenario. There are, however, a number of ‘suspicious’ coincidences, which indicate a deliberate act of diversion.
I have a “constant thrust” model, which can be interpreted as AT mode or, as it has just popped up, “engine failsafe” mode: the trajectory reasonably well fits BTO/BFO, and it ends up at ~100E, 27.7S, 6 km altitude. Moreover, at 19:41 the location is at ~4 km altitude, ~100-150 km south of the place where Kate (the sailoress) saw ‘something’, or at Car Nikobar 18:50 if to integrate ODEs from earlier time. What I do not know is how to reasonably connect the trajectory to 18:22 position at 9-11 km altitude. The assumption of a technical failure makes this possible.
You are welcome to help to discard the “technical failure” scenario if you have sounding arguments against it.
Spoof??
Yes, it certainly runs into the motive question. It is so bizarre, it is hard to embrace. I don’t see a way to discard it other than on emotional grounds.
Mechanical failure??
Hard to reconcile with radar data, Inmarsat data, lack of communication,… Someone was flying that airplane, and did not attempt to land it at any of the many available places.