Search crews in the remote southern Indian Ocean have completed a task so vast and technically ambitious that it once seemed impossible: to scan a three-mile-deep, 120,000 sq km swathe of seabed using a side-scan sonar “towfish” in hopes of finding the wreckage of missing Malayia Airlines 777 MH370. After considerable delay due to mechanical problems and bad weather, the final square miles were scanned on October 11 by the research vessel Fugro Equator. The $180 million project turned up no trace of the missing plane, though searchers did find several long-sunken sailing ships.
The Fugro Equator will next use an AUV, or autonomous sub, to scan selected areas where the rugged seabed topography was too rough for adequate imaging by the towfish. “The total combined area of the spots that will be surveyed with the AUV is very limited, but still required to ensure that no area has been missed,” says Fugro spokesman Rob Luijneburg.
The Australian National Transport Board (ATSB), which is overseeing the search, expects this fill-in work to be completed by the end of February.
The fact that that the Pennsylvania-sized towfish scan had been completed was first noticed by Richard Cole, a space scientist at University College London who has been meticulously logging the search ships’ movements via online tracking services and then posting charts of their progress on Twitter. “At the completion of Equator’s last swing in mid-October the target of 120,000 square kilometers had been achieved, at least as far as my calculations show,” Cole wrote me last week. Both Fugro and the ATSB subsequently confirmed Cole’s observation.
The 120,000 sq km area has special significance in the effort to find MH370, because ministers from the four countries responsible for the search have made it clear that if nothing turns up within it, the search will be suspended. Unless new evidence emerges, the mystery will be left unsolved.
Plans to search the seabed were first mooted during the summer of 2014, after officials realized that metadata recorded by satellite-communications provider Inmarsat contained clues indicating roughly where the plane had gone. At first, investigators were confident that the wreckage would be found within a 60,000 sq km area stretching along the 7th ping arc from which the plane is known to have sent its final automatic transmission. When nothing was found, ministers from the four governments responsible for the search declared that the search zone would be doubled in size.
In December, 2015, officials declared that the search would be completed by June, 2016. In July of 2016, Malaysia’s transport minister indicated that it would be finished by October; weeks later, a meeting of the four ministers pushed the completion back to December. Last week, the Australian Safety Transport Board announded that “searching the entire 120,000 square kilometre search area will be completed by around January/February 2017.”
In an email to me, ATSB communications officer Dan O’Malley said his organization will issue a report on the seabed search once the full scan is completed. Under ICAO guidelines, Malaysia will only be obligated to release a comprehensive final report on the investigation once it has been formally terminated; so far, Malaysia has only talked of suspending the search, not ending it.
The bulk of the work has been carried out by ships pulling a sidescan sonar device on a long cable. This so-called “towfish” uses reflected sound waves to create an image of the sea floor. By sweeping up and down the search zone in much the same way that a lawnmower goes back and forth across a lawn, searchers have been able to build up a comprehensive image of the search area’s bottom.
But, just as a landscaper might have to use a weedwhacker to clean up areas around rocks or stumps, searchers will have to fill in gaps in the scan where underwater mountains, volanoes and escarpments have prevented the towfish from getting a close enough look.
“A total area for search by the AUV is difficult to give because it concerns a number of relatively small spots that all are relatively difficult to reach and in difficult terrain,” Luijnenburg says.
The fill-in work will be carried out by an Autonomous Underwater Vehicle deployed from the Fugro Equator. The Kongsberg Hugin 100 is capable of diving to depths of up to 15,000 feet and can maintain a speed of 4 knots for up to 24 hours before being retrieved by the mothership. Whereas the side-scan sonar of the towfish has a resolution of 70 cm, the AUV’s sonar has a resolution of 10 cm, and so can image the seabed in much greater detail, as well as taking photographs when necessary.
Meanwhile, as the AUV work progresses, a Chinese vessel will deploy an Remotely Operated Vehicle (ROV) to take photographs of targets previously identified as being of interest. The ATSB has stated that none of these targets are “category one” targets, namely those likely to have come from MH370, however. Says Cole, “In the absence of category one targets there must be a list of targets from the sonar search that look the most interesting, so the question is how far down that list they are going to go.”
While the fill-in work must be carried out in order for the work to be declared 100 percent done, little prospect remains that the missing plane will be found in the southern Indian Ocean.
NOTE: This story was updated 10/26/2016 to include comments from Fugro spokesman Rob Luijnenburg.
@TBill. “assuming moonless night was intentional (to be invisible to planes and satellites)”.
Well I wonder if he would need that invisibility if not needing intending to traverse the Peninsula, darkened. His flight would be routine.
@TBill. Thanks for the timetable. Well found. My last crossed with your 11:02.
Another possibility is MH194 2020 to Mumbai. The point though is that he had a much easier egress if March 8th was central to him than reversing across the Peninsula, dark.
To me that weakens, seriously, long range planning leading to the Igari turn back, unless he was deliberately being confrontational and there is no reasonable motive I know of for that.
@David, @TBill, From what we know, both Z and F were scheduled for this flight atleast 7 days before. So it is therefore difficult to argue that it was planned. Unless, a request was put in well in advance. Pilots do this often, but requesting a flight in February for March 8th would have stood out IMO. Subsequently, neither Z or F (if it wasn’t planned) could have anticipated the moonless night. This would have been shere happenchance. IF Z did do this, he would have been more than confident in his skills no matter the circumstances. Backtracking over the peninsula on a moonless night would have been a sinch for Z. Having said this, hijackers could have planned it and sought out the flight that fits their needs best. Then the question is: why this particular flight?
@Gysbreght. Thank you for your response about ACARS.
“..at 18:03 the ground station attempted to send an ACARS message to the aircraft via SATCOM and there was no response…” FI p48 shows the message as having “failed”. That is expanded at FI App 1.9A where that ACARS downlink notes, “up intercept aircraft not logged on”. At risk of repetition, the question remains whether such a log-on failure could have been the result of flight identification becoming unavailable to the SDU through damage to boxes, power supplies, wiring, or deletion, or being overwritten? Possibly it is rhetorical: I assume only one very familiar with this equipment would know.
So far as I am aware there is no explanation for why the flight ID was missing at the subsequent AES initiated logs-on and I suspect that is related. I speculate that the aircraft might not transmit any ACARS report without a flight ID and likewise not respond to the 1803 message if it did not know its flight identity. Moreover it might not recognise that incoming ACARS messages were intended for its attention.
To expand the FI p43 quote,”In the event that the aircraft ACARS unit has been silent for longer than a pre-set time interval, the ground station can ping the aircraft (directly or via satellite). A ping response indicates a healthy ACARS communication”. You pointed out that the next para specified the time interval as 30 minutes and, after a silence of more than that, MAS Operation Control Centre (OCC) will send a text message via ACARS or will call via SATCOM. Belatedly MAS did those.
Still, seeing that the pings post the 18:25 log-on were not at a nominal 30 minutes and since the AES response to them surely did not indicate a ‘healthy ACARS communication’ I surmise that there were no pings sent specifically to test for ACARS integrity. What is the explanation for that I wonder (also probably rhetorically)?
@ Richard Cole
Thanks for this succinct yet clear explanation!
(“the start of the 50ms slot” you mean 500ms right?)
Two more questions :
a) The round trip time to ‘nominal terminal’ is constant? Why is it not released by Inmarsat? What is it’s value?
b) If a plane flies at 10km altitude, just above the sub-satellite point, it will have a negative BTO? Will GES be able to record the packet? Or is it discarded?
@Sk999
Thanks for the clarification on the P channel being continuous!
It now makes sense that the AES is not allowed to transmit if it’s not synchronized to the P channel.
Sorry to be a pain, but I’m not clear your explanation of nominal return time.
You say it is :
the time that the outbound P channel superframe was sent
+ the time offset from the unique word for each slot
+ about 0.5 seconds – the round trip travel time.
This gives the nominal arrival time? Then BTO is the difference between this arrival time and actual arrival time?
So your “about 0.5 seconds – the round trip travel time” is the same as Richard Cole’s “round trip time to ‘nominal terminal'”?
If so could you please also answer my a) and b) questions above.
@David:
The aircraft ACARS was apparently set to “SATCOM only”. Therefore any ACARS transmission requires a SATCOM datalink. FI figure 1.9K is from the SITA log (Appendix 1.9A), the ground element of ACARS. It reports that the attempt to transmit a message to the aircraft ACARS has failed. The reason for that is that Inmarsat was unable to contact the the airplane and open a datalink. The Inmarsat log says: “18:03 – No Response to Ground to Air DATA-2 ACARS Data. Link lost at sometime between 17:07:48nand here.”
There are two separate ‘ping’ mechanisms. The Inmarsat GES pings the aircraft SDU every hour to verify that it is still logged on to the SATCOM. That are the five ‘handshake requests’ recorded in the Inmarsat traffic log.
FI page 43: “In the event that the aircraft ACARS unit has been silent for longer than a pre-set time interval, the [ACARS] ground station [MAS>SITA] can ping the aircraft [ACARS] (directly or via satellite). A ping response indicates a healthy ACARS communication. Pre-set time interval for MAS B777 is 30 minutes.”
FI page 46: “Position reports were programmed to be transmitted every 30 minutes. (…) The first (which was also the last) position report was transmitted via ACARS at 1707:29 UTC, 07 March 2014”
The first ACARS ping should have been sent by the ACARS ground station at 17:37, 30 minutes after the last ACARS position report. Factual Information is silent on the question why MAS did not send it at that time.
Regarding the missing flight ID I seem to remember that Guarded Don explained some time ago that the SATCOM system does not require a flight ID, since the SDU is identified by its unique identifier.
Richard Cole, Dennis W, sinux, sk999 et al
I am glad to see a more in-depth discussion of the BTO again. Allow me to point out a minor puzzle that I hope the more knowledgeable among you will be able to put to bed. My question concerns the “tick” of the p-channel(s) to which all remote stations synch their timing and which define frame boundaries/slots for R and T channels.
The p-channel frames are 500 milliseconds or multiple thereof, and a single p-channel superframe defines 8, 16, 32 and 64 random access slots for R channel at respective data rates of 0.6, 1.2, 2.4, 10.5 kbits/s. All p-channels themselves are synched to a common “tick”.
When we look at the satcomm logs pre-disappearance, the timestamp for the p-channel tx is (generally) logged at xx.905 or xx.405 seconds, +/- 0.1 millisecond with only two minor exceptions: 0.907 (16:09:45) and xx.410 at 16:56:15. There are only two larger deviations of xx.420 and xx.413 at 18:04.
At 1825 on p-600 we see a total different pattern: xx.852, xx.572 and xx.213. After the new log-on has been established, the timing seems to settle down again, but now displaced by ~2 milliseconds at xx.407 and xx.907 timestamps compared to the pre-disappearance pattern. The exception, again, is the P-600 Tx associated with the new logon at 0019, where we see a similar pattern to previous p-600: xx.572, xx.212, xx.852. Once that logon is established though, the timing pattern for p10500 seems to change again (post 00:19:37, unanswered), now showing as xx.000.
My questions are as follows:-
1. Why is there a shift in the p-channel timestamps, from x.405 / x.905 to x.407 / x.907 to x.000 when this p-channel “metronome” is supposed to be regular?
2. If all p-channels are themselves synchronised, why are the p-600 timings different distinctly different (x.572, x.212, x.852) and why are they no longer multiples of 0.5 seconds?
@All. On March 8th, an anonymous JAL captain said he tried to contact MH370 on the emergency channel at the request of HCM (in his statement the captain said it could have been Z or F, but he was sure (???) it was the FO. They contacted MH370 at just after 1.30 a.m. but heard static and mumbling and the connection was lost. What is odd is that according to the official records HCM did not come into action until 17 minutes afterMH370 failed to report in. At 17.19:30 KLATC instructed MH370 to report to HCM. Does anyone know the time discrepancy here? Did HCM respond much sooner than the 17 – 20 minutes, which was stated at that time?
@Keffertje, We’ve had to swat this one down before. This rumored radio call is self-evidently preposterous: when you call someone up on a radio, it’s not like calling someone on a phone, where you know who you’re talking to; even if such an occurrence did take place — and there were so many spurious reports in the week after the disapperance, that there’s no reason to assume this wasn’t spurious, too, since it was never verified — there would be absolutely no reason for the JAL captain to assume that the “static and mumbling” originated from MH370.
@Jeff, Thank for clearing that up. I was also like, Huh???? this doesn’t add up. Thank you.
“Flight ID missing”
The flight ID for the SDU is ONLY available via the Left AIMS Cabinet (aka the Left Electronic Brain of the aircraft).
If the Left AIMS Cabinet is damaged, the flight ID will be missing.
The Left AIMS Cabinet is next to the Crew Oxygen Bottles, which were topped up prior to flight.
Some Oxygen Bottles were required to be replaced because they were prone to rupture. See Airworthiness Directive 2009-21-10 R1.
The Left AIMS Cabinet supplies air data to the Left Transponder.
Near the oxygen bottles are some HYDIM cards which control some hydraulic functions. Flaperon PCUs would change to bypass mode following engine flameout. Flaperon is free to flutter resulting in trailing edge damage.
The single Audio Management Unit, which is required for radio communications, transmits and receives data ONLY on the Left ARINC 629 bus, which is outboard of the Crew Oxygen Bottles.
If the aircraft was slowly depressurising and the crew, flight attendant or a passenger programmed a diversion to Banda Aceh via Nilam/Sanob, but does not delete the route discontinuity, then the aircraft ends at the ATSB hotspot in the SIO.
Outboard of the Left AIMS Cabinet, is the P100 Power Panel. Damage to the panel or wiring can disable the Left IDG and Backup Converter. The Left IDG normally powers the Left Main AC Bus. The right IDG would then power the Main and Transfer buses. ELMS would load shed equipment.
Thus, the seventh arc can be after the right engine failure, and not the second. The aircraft can be up to 100 NM from the seventh arc, which has NEVER been searched.
@OXY
For what it’s worth, that flight path SANOB to Banda Aceh goes almost directly to OLPUS relatively near the search zone, as you stated
@OXY, you wrote, “If the aircraft was slowly depressurising and the crew, flight attendant or a passenger programmed a diversion to Banda Aceh via Nilam/Sanob, but does not delete the route discontinuity, then the aircraft ends at the ATSB hotspot in the SIO.”
So we know that didn’t happen, don’t we?
Oxy,
Excellent, you have just added one more brick into my hypothesis. If you wish to discuss, you can ask Jeff my e-mail.
—–
Keffertje,
Just of note that it is very likely that MH88 was really in contact with MH370.
@OXY
“Some Oxygen Bottles were required to be replaced because they were prone to rupture. See Airworthiness Directive 2009-21-10 R1.”
I am confused why you are mentioning this directive. According to the Factual Information, MH370 had composite type (eg KEVLAR) main crew oxygen cylinders. I am thinking the directive applies to the heat-treated steel type of cylinder, not on MH370.
@All
Tonight’s brainteaser:
Speed immediately prior to turnback is M0.83. Begins 7Nm radius turn at 17:22 (22Nm turn takes 3 mins). Then from 17:25 to 17:53 acft flies at M0.87 (taking Mach 1 as 592Kt, at 42C, nominal FL350) and covers 247.5Nm in 28mins, benefiting from 15Kt ave tailwind. From 17:53 to 18:22, acft continues at M0.87, and covers 251.5Nm in 29mins, benefiting from 5Kt ave tailwind. Between 18:22 and 18:37:15 (mid point of FMT) acft slows from M0.87 to M0.81 covering 123.5Nm in 15mins, then continues at a constant, unwavering M0.81 at FL350 until fuel exhaustion, crossing 7th arc at S37.67, E89.08*, after taking varying windspeeds and upper air temperature on journey south into account.
It looks as if M0.81 manual intervention speed, at FL350 was set on the MCP for the flight, post FMT, while remaining in LNAV nav mode
The big question is why choose M0.81 for the journey south? Hint, one possible reason is one hour at M0.87 to bamboozle anyone happening to be in front of a radar screen, then needed to be followed by 5.75hrs(approx.) at M0.81 to maximize mpg, to get as far as possible into the SIO
*assumes great circle path from IGOGU through ISBIX, projected south to 7th arc, toward manually inserted, along-track waypoint.
Controversial I know, and I apologise in advance.
@Oxy
As noted in AD referenced (Airworthiness Directive 2009-21-10 R1.) the cylinder which ruptured was a steel cylinder, AVOX Systems serial number ST82498.
A few questions.
Q.1.
Is this the cylinder specification ?
(https://www.law.cornell.edu/cfr/text/49/178.44)
Q.2.
Was cylinder, AVOX Systems serial number ST82498, installed on Boeing 747-438, VH-OJK. on Flight QF30, (from London to Melbournne via Hong Kong), that ruptured approximately 55 minutes after departure from Hong Kong, while the aircraft was cruising at 29,000 ft (FL290),, 475 km north-west of Manila, Philippines, on 25 July 2008, which caused an explosive decompression, resulting in an emergency landing in Manilla ?
ATSB Report (http://www.atsb.gov.au/media/2409291/ao2008053.pdf)
Captain Interview (http://www.flightpodcast.com/episode-6-john-bartels-qantas-qf30)
Q.3.
(A) I assume you are suggesting that the same type of steel cyliner was (or could have been) installed in 9M-MRO ?
(B) TBill stated, “According to the Factual Information, MH370 had composite type (eg KEVLAR) main crew oxygen cylinders.” Are you suggesting that the two types of cylinders are effectively “interchangeable”, and/or that the FI may be wrong ?
Q.4.
(A) Do you have a specification reference for the Kevlar cylinders ?
(B) Are there any known instances of the Kevlar cylinders rupturing ?
(C) Are there any known AD’s for the kevlar cylinders ?
Q.5.
(A) How are the cylinder(s) actually mounted (aligned) in 9M-MRO, (in relation to the surrounding equipment cabinets / racks – and the fueselage skin) ?
(B) Assuming the cylinder ruptured in a similar manner to the QF30 cylinder, what would be the trajectory and force of the resulting cylinder components, (in both the steel and kevlar cases) and how much damage could those liberated pieces physically do (noting the damage in the ATSB report of QF30) ?
@ROB
Re Tonight’s brainteaser:
And your obvious FINAL WAYPOINT is 44s 88e ?
Nice and easy number(s) to remember !
This has been discussed before.
Some time ago, I examined 44n 88e as the “intended final waypoint” for a 90 degree left turn, for a 23 mile final to ZWWWW, of the hijacker scenario. But being a “dark moonless night”, our intrepid hijackers stuffed up “north and south” on the latitude, and did not realize it !!
@Rob. Very *ahem* interesting. Do you really regard a 7Nm diameter turn as credible? At what airspeed and bank angle??
@ROB
Specifically, Hijacker Flight Plan was:
WMKK IGARI 065817N1033813E 070000N1033714E LOSLO KP967 VAMPI NILAM IGOGU 4488E ZWWW
@Paul Smithson
Ahem, Paul if you look again you will see I said 7Nm RADIUS turn. A 7Nm radius turn is possible at M0.83, particularly if manually executed, and overriding the over-bank protection.
@ventus45
Any hijacking scenario, other than the one neatly executed by our PIC, and no one else, is pure moonshine, if you pardon the pun. 🙂
@ROB, We all understand that you feel this way, but merely stating it over and over again does not make it so.
If you can demonstrate why it is impossible for hijackers to take over control of the plane via the E/E bay, then please do so. Merely harboring a gut feeling that things unfolded a certain way is not dispositive.
@ROB
you said:
“Between 18:22 and 18:37:15 (mid point of FMT) acft slows from M0.87 to M0.81 covering 123.5Nm in 15mins, then continues at a constant, unwavering M0.81 at FL350 until fuel exhaustion, crossing 7th arc at S37.67, E89.08*, after taking varying windspeeds and upper air temperature on journey south into account.”
I have very compelling analytical reasons to believe that the aircraft was traveling at a ground speed of around 400 knots between 18:22 and 19:40.
@ROB: RE “Tonight’s brainteaser: Speed immediately prior to turnback is M0.83.”:
Why M0.83 when it was M.82 at 1701:43 and 1706:43 ?
@Gysbreght
As regards to page 46 of factual information where does it say the first (which was also the last) 17:0729 position was? And what do they mean by “first”? I thought 17:0643 shown on the table below it. Was the last position or is there a delay or something?
@Joseph Coleman: “Where does it say” ?
On page 46.
@Gysbreght
Why get caught up in the detail, look at the big picture for once. Anyway, what’s M0.01 between friends?
@Gysbreght
Is there position report via ACARS for 17:0729 and if so where is it stated? Do they mean position as in Geographical or position as in status?
@Joseph Coleman:
I’m sorry if I don’t understand your question. Here is the entire paragraph. It seemed quite clear to me:
@Paul Smithson
I am not an expert on the AMSS protocols, so these are really guesses. We are also not clear exactly which times Inmarsat decided to log, against each channel type.
>1. Why is there a shift in the p-channel timestamps, …when this p-channel “metronome” is supposed to be regular?
The AMSS papers on-line state that there is no requirement to synchronise the GES P channel timing to UTC, so there is nothing to prevent the Perth GES (in this case) changing the timing basis. I can’t think of an immediate reason why it should, though, beyond general drift. The system is not particularly sensitive to small changes in timing, and still achieving full function, given the long signal travel times.
>2. If all p-channels are themselves synchronised, why are the p-600 timings different distinctly different (x.572, x.212, x.852) and why are they no longer multiples of 0.5 seconds?
There is a suggestion in one of the AMSS papers.
“With the exception of the 0.6 kbits/s P channel, the duration of the interleaver is 500 milliseconds. For the 0.6 kbits/s, the interleaver is 384 bits corresponding to 2/3 second.” This interval matches those in the data rather better.
@sinux
>“the start of the 50ms slot” you mean 500ms right?)
No, I was referring to the ‘slot’ (perhaps poor term) during each 500ms frame during which the replies are received from the AES (and maritime and mobile stations) across the hemisphere visible to a single satellite, given their variations in distance from the satellite.
>a) The round trip time to ‘nominal terminal’ is constant? Why is it not released by Inmarsat? What is its value?
Isn’t this what is defined in section 5.2 of the DSTG report (499962μs)?
>b) If a plane flies at 10km altitude, just above the sub-satellite point, it will have a negative BTO? Will GES be able to record the packet? Or is it discarded?
Don’t know. Carrying one sign bit for the BTO would not be a large demand on storage, even if they wanted to record the small number of aircraft at the sub-satellite point. The figure of 499962μs is definitely round-trip time for Perth GES to ground level (rather than to some arbitrary altitude above any possible aircraft).
@Gysbreght
Your right it’s cleary explained. I missed reading the word “collaboration”. Approx 30 minutes reporting after take off for first and last, not 17:0729 as an individual field of information. Perhaps I should stay off here while on the beers (unfocused) 🙂
@OXY , you stated;
“The Left AIMS Cabinet is next to the Crew Oxygen Bottles”
Could you clarify for me please, if the above statement is correct,
then what part of the AIMS is located in the starboard side of the
top shelf of the ‘Main Rack’ which is located against the aft wall
of the EE bay?
(Viewing the 1st picture here;
https://globusmax.wordpress.com/
we can see four of the AIMS modules in their Main Rack location, this
is seen in the upper right of the picture. Also visible is a whitebox
on the left of the picture which is the P200 Right Power Panel, and
visible in the centre of the picture is the P210 Right Power Management
Panel.)
If your above statement is correct, would it also be true to say the
‘Left Aims Cabinet’ is outboard of the Main Battery?
and would it be true to say the ‘Left Aims Cabinet’ is located under a
shelf, and on top of that shelf sits the P320 Ground Service/Handling
Panel?
@OXY
“The flight ID for the SDU is ONLY available via the Left AIMS”
What is the source of this information?
@Gysbreght. You note about the ACARS missing ping, “Factual Information is silent on the question why MAS did not send it at that time”. Yes, and in particular I would have expected that to be automatic.
Thank you for helping where you can but a heap of questions and points remain in my mind. Among them:
CURIOSITIES:
• What the point is of loading ID to the SATCOM (as distinct from the separate ACARS need, ie in case it utilises VHF) if it hums away without it? The unique identifier entered in setting up the SDU will enable aircraft identification and who is using the service but not the flight so why is that loaded if not needed?
• Why the loss of ACARS was not interrogated each 30 mins, not only at 17:37 but particularly after the 18:25 when there was a SATCOM link. Might this be because if switched off that could be detected?
ISSUES:
• Could the ACARS/SATCOM be effectively disabled simply by repeating in flight the pre-flight loading of flight data using bogus or non-sensical info?
• Would the flight ID be lost if the route were changed on board or even from the ground (possible?) from the flight plan? To me a new route entry could well render the old flight ID redundant.
• As I speculated earlier, is there a conceivable reaction of the SDU to loss of flight ID to then reboot without it ie at 18:25?
• How could its flight ID become unknown to the aircraft (eg OXY’s oxygen cylinder, nose wheel explosion, power isolation due to window fire etc)?
If the wreckage is not located, this element of the mystery will need further attention. It has not been really important as yet, the focus properly being on locating the wreckage.
Under ISSUES, “Could the ACARS use of SATCOM….(in place of …ACARS/SATCOM)
@Richard C. Thanks for your response. I agree, there is no reason to suppose the 0.5s “tick” to be UTC whole seconds so I’m not worried in the slightest if it turns out to be x.405 / x.905.
What I do find very strange indeed is that this P-channel Tx timing appears to begin at .405 / 905, move to .407 /.907 and then to .000 / .5, over a relatively short period. And this p-channel “tick” is the timing basis for the entire system and all stations communicating with it. Guarded Don has previously advised that we should be careful not to assume that the rather approximate log timestamps relate directly to the much more precise BTO timing measurements. Notwithstanding this proviso it appears to me to be an odd observation without adequate explanation.
As regards the odd timing for P-600, I also spotted that FEC factor of “about 2/3 of a second” (more precisely 384/600, or 0.64, if I have understood correctly) – but this doesn’t match up with the fractions observed, with relative “spacing” of ~0.360s. Hopefully one of the experts can chip in and steer us on to the path of righteousness.
@Rob. 7NM diameter is a bank angle of 40 degrees at TAS ~450kts. Really?
@David said; “How could its flight ID become unknown to the aircraft”?
The flight ID became unknown to the SDU. After IGARI, due to
power interruption and/or damage to data connection cables, the SDU
never sent any information other than ‘hello, I’m still listening/answering’
type messages.
——–
@Ventus45 said “would I be correct in assuming”…
Yes, that is what I meant & your ‘Q’ & ‘W’ are approximate points – ‘Q’ is
approximate because that’s about where my eyes put the tip of that Lido
graphic ‘arrow head’. (Note, the actual position the graphic producers
meant to indicate could be a bit beyond the ‘arrow head’, in which case,
the knock-on effect would be to lower point ‘W’ to under N571, which is
why I mentioned that an aircraft {‘W’} flying eastward on N571 can be
offset to the right of the centre line of N571, {so i.e., ‘W’ would be
lower} yet still actually be within the boundaries of N571, according to
the Malaysian eAIP).
‘Plausible’ wasn’t my wording – I thought it “likely” that the source of
the last point was a Singaporean AWACS, given the reference to a
Singaporean radar source in the ATSB report. Also, VictorI believes there
was a “Singapore Airborne Early Warning & Control (AEW&C) aircraft in the
vicinity of the Andamans” (although his belief arises from different
reasons than the Lido image).
https://jeffwise.net/2016/06/27/mh370-news-update/comment-page-3/#comment-174227
If it was a Singaporean military aircraft, the question arises – why is
only one datapoint shown – if a radar was flying eastwards, shouldn’t
there have been more datapoints?
Possible explanation is that after the radar source cleared Ketchal
Island, it began descending and so put itself below the ‘radar horizon’,
which wouldn’t be difficult as 200 nautical miles (~370km !) is about
the limit of the advertised range for the Singaporean gulfstream G550
AWACS radar.
(Why descend? Well Singapore has an interest in monitoring vessels
approaching the Malacca Strait, so it may have begun descending to
check unidentified sea vessel radar targets. Like what? Perhaps yachts
….like the one Kate Tees was sailing when that unknown aircraft
which she said was “even lower than 10,000ft” flew by, and she said
about the passenger windows,
”I could see where the windows should have been”…“but the whole hull
just appeared to be one plain surface, as though they’d been painted
over”…)
(Could have been a military aircraft hull, couldn’t it?)
Another reason why only one datapoint is that MH370 itself may have
begun descending – we know Oleksandr, from his spiral descent graphic,
considers a MH370 descent around this time to be possible.
The only figure I’ve seen for the range of a KC-135 radar is 150nm –
for Singapores KC-135R military aircraft, I don’t know what radar
they have installed, but the Singapore military tends to maximise the
capabilities of their aircraft, so a further ranging radar may be
installed – anyone have a copy of Jane’s?
@Rob, begging your pardon for failure to see you stress radius, not diameter. Yes, 14NM diameter is what you might expect but this isn’t what is depicted in the “radar trace” graphics that we have in the public domain.
Regarding the P channel sync pulse.
”
(This may be way off beam – so take with a large swig of your “preferreed” handy – just in case ……….)
I was under the impression (perhaps wrongly) that “the master SYSTEM clock” for I3F-1 was generated by the system control station in Burum Netherlands, and presumably “the Burum system clock” is set to UTC. I further assume that the Perth GES gets it’s “time base” directly from Burum via I3F-1.
Now, when the system was designed, the sat was supposed to be “stationary” (to a fairly tight tollerance) in orbit, and the “nominal” distance from Burum to I3F-1 and the “nominal” distance from Perth to I3F-1 were known, so the “nominal trip times” were known, and the “system software” would have been designed to take account of that.
Today, I3F-1 is no longer “stationary”, so the individual path lengths between I3F-1 and BOTH “the control station” (Burum), and “the operational service traffic station” (Perth) are continuously changing. Hence the total path distance Burum -> I3F-1 -> Perth is continuously slowly changing, and thus the total “path time” is also continuously slowly changing.
Therefore, as I3F-1 slowly got more and more “wobbly” with the passing of the years, the P channel sync pulse “received” at Perth GES oscillates “back and forth” from the “originally designed” time delay, and that “oscillation” may have (at some point) become too large for the original software timings to handle, ie, they have moved “out of original tollerance”.
So, some means of “compensating” would be needed to “keep the system operational”.
There would have to be some kind of “offset” built into the “present day system”.
Perhaps this is a clue to Inmarsat’s confusing, and never properly explained “virtual terminal” ?
Thoughts – anyone ?
@Ge Rijn. In an Oct 30th 10:58 posting about the SDU power source I wrote, “As before if the -6000 in 9M-MRO were to operate on DC with just the 115ac to it, it would need an inverter…”.
On re-reading this it had me standing on my head. It should have read, “…operate on DC when designed just to accept 115V ac, it would need an inverter..”
I hope that has not had a like effect on you.
@David
It had not but I read it as a mixing up terms by you.
IMO the SDU (and all electronicis) work only on DC.
An inverter changes DC into AC which is not useable by electronics.
The SDU has it’s own ‘Transformator Rectifier Unit’ which exepts 115AC as we concluded before and a direct connection to exept 28V DC regarding the info from @Marc.
My question then was if the SDU was possibly directly backed-up by a battery. It seems not likely to me for I thought the SDU is not a vital flight-instrument.
But I cann’t find the information to be sure.
@Ventus45
>I was under the impression (perhaps wrongly) that “the master SYSTEM clock” for I3F-1 was generated by the system control station in Burum Netherlands
I think the master C-band downlink RF frequency is generated at Burum. This may be important to avoid cross-satellite interference, and be a regulatory requirement. The AMSS papers on-line suggest there was not a cost-effective reason to coordinate across the network (i.e. set to UTC) the timing of the protocols that run on that link, so they are set at each GES.
>Now, when the system was designed, the sat was supposed to be “stationary” (to a fairly tight tolerance) in orbit
No, the inclination of I3F-1 was set to 2.7deg at launch and it took 4 years to drift to zero (graph below). Thereafter it was held near zero until 2012 when, presumably, the N-S station-keeping fuel ran out. This strategy presumably achieves maximum lifetime for given fuel load. Thus, the system must have been originally spec’d to cover an inclination of 3 deg at least. Agreed, that there must be some limit for the inclination of the satellite and keeping the system operational.
https://www.dropbox.com/s/x9aha8sw1r5vgop/3f1_inclination.jpg?dl=0
@Richard
you said
“I think the master C-band downlink RF frequency is generated at Burum.”
I do not believe this is correct or else there would be no eclipse effect. The C-band down link, I believe is generated by a free running oven oscillator in the satellite.
@Ge Rijn. “An inverter changes DC into AC which is not useable by electronics.” Yes.
Without a DC connection, an inverter would provide 115Vac and a TRU would recify back the DC supplies needed. However, from the documentation DC or AC back up is provided.
However form the documentation NEITHER DC or…
Search goes north, it seems.
http://www.abc.net.au/pm/content/2016/s4567163.htm
@David
You almost got me confused again 😉
But now it’s clear. Thanks.
NO AC (back up generator) or DC (battery) back up for the SDU.
@Richard
Interesting. Thank you for that. I do not believe 34S is far enough North, but I was not invited to the meeting.