[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.
Oleksandr,
I note that you are still discussing ‘waypoints’ & how or why 9M-MRO’s navigation after 17:21 would have been conducted. It’s entirely reasonable to make the assumption that, throughout the flight, the pilot in control used the AFDS (Autopilot Flight Director System) and the AFDS was operating with LNAV input from the FMS. The FMS is programmed to fly ‘legs’, each leg is a ‘fly to a fix’ instruction and 15 leg types are defined. Flying a track to a waypoint, a navigation fix, is only one of that list. Even a TF leg, Track to Fix, implies a number of options to define the fix: e.g. nav database waypoint, explicit lat-long and others. To enter a set of legs to take the aircraft from the turn at IGARI via Penang Island, out over the Str of Malacca and on would have been a trivial CDU key entry task for someone operationally familiar with the B777 or similar aircraft.
With regard to RADAR, take a look an image I created to illustrate the view of the Thai RTADS-III RADAR sites: i.imgur.com/TBYllAA.jpg (prepend with http-colon-solidus-solidus). The two TNI-AU sites at Sabang & Lhokseumawe are also annotated on the image. My analysis remains that the RTADS-III Phuket and Khok Muang sites were the source of the data presented in the “Beijing Lido” image:
a) we know that atmospheric effects recorded in the area on the night 7-8 Mar would have reduced the effective range of these two RADAR units – the start and end targets in each scan segment are a similar range from each site. Immediately south of the RADAR head at Phuket there is high ground with a steep north facing facet which I hypothesised may cause backscatter noise at that azimuth, hence the returns in that scan azimuth may be disregarded. Disregarded or not, it doesn’t affect coverage of the approaches over Str of Malacca as depicted on the image;
b) I’ve depicted limited scans on the image – speculating that they would not scan inland and incur unnecessary processing upstream in the RTADS Command & Control system which manages the integration with civil ATC systems for friend-foe ID using interrogation of flight plans, real-time civil SSR data, etc;
c) from a ‘political’ perspective the release of a limited dataset may have been regarded as adequate – we know the Mlsian authorities are somewhat lacking in their perception of what is appropriate communications.
The pattern of the dataset presented in the Beijing Lido image does not match the location of Malaysian RADAR site on Western Hill, Penang Island, nor does it correlate to the Lhokseumawe site. Both segments of the dataset appear to degrade in quality from east to west. That observation alone is inconsistent with Western Hill, Lhokseumawe or Sabang being the souce of the data.
As to comments that the image doesn’t look like a Thales, Selex or other manufacturer’s RADAR scope display: I wouldn’t expect a ‘screen shot’ to be published. All these systems provide an external representation of data in an industry standard format that’s readily parsed to create a data file for use by any mapping application program. It’s not difficult, it’s not magic.
I will readily consider any further corroborated information that may exist.
:Don
Airlandseaman,
You said “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”, and also “…loss of primary power is the most likely explanation”.
Is supply of data from INS to FMC affected in both of these scenarios?
Oleksander,
If I might answer your question regarding INS data, the FMC and the AES.
It’s been described in this comment thread, I think, that various software functions are hosted on AIMS. One of those software functions is the Flight Management Compute Function (the FMC itself). Another function manages the conversion and distribution of data around the various avionics systems.
The data words required by the AES are sourced in the ADIRU (inertial data) and the FMC (lat-log co-ords).
There are multiple ADIRU sources & AIMS itself is designed with high levels of redundancy.
:Don
Don,
Thanks, interesting analysis. At least we converge that two sections of radar data in the “Lido” image are likely coming from two different radar systems, and the gap is a result of merging. Does this explain the difference between “Lido” image and ATSB report in your opinion?
DEM (Digital Elevation Model, data.geocomm.com/dem/) has approximately 90 m resolution, thus the effect of the terrain can be estimated more accurately if you know exact location of the radars.
With regard to flight mode up to Penang, I have no doubts that it is possible to program FMS for a curved path using raw lon, lat. However, for what? A trivial explanation is that MH370 was flown manually; moreover a shape of the curve is more consistent with the magnetic heading. In simple words it looks like MH370 was flown to Penang manually by compass.
Lauren,
Sorry for the delayed response on the subject of the air conditioning packs: the left and right packs derive power from the respective AC busses.
Similarly, the Left & Right FWD & AFT cabin outflow valves are powered by L & R busses. I’d expect that the outflow valves would failsafe in current position if power was lost.
:Don
Don,
Is my understanding correct that while failure is possible, AIMS has a higher level of redundancy compared to the ability of AES to function properly in case of either event?
Jeff has recently posted a survey “Airliners in Unusual Attitudes”. Here is an example of ADIRU failure:
www(dot)atsb(dot)gov(dot)au/publications/investigation_reports/2008/aair/ao-2008-070(dot)aspx
Oleksandr,
It is understood by the IG that the image used by ATSB as figure 2 in ‘Definition of Underwater Search Areas’ was provided by the Malaysian based investigation team with no detail of its provenance.
So, back to the Malaysian element of the process.
I regard that figure only as an illustration. If one overlays a cruise speed turn, initiated near IGARI, onto that map then its accuracy is immediately questionable.
I am in no way suggesting that the turn and progress toward Penang didn’t occur, rather, I am questioning the motivation of the Malaysians to persist in denying it during the first week.
I have seen RADAR range calculated with consideration for the region’s terrain data & my analysis holds up.
:Don
Oleksandr
AIMS is designed to be highly redundant, I won’t try to describe how but it’s an impressive design. It hosts a number of important functions so demanding resilience to failure.
The core of the AES, the SDU, is provided with a physical ‘IRS’ connection from the L & R AIMS cabinets simply because the Data Conversion Gateway Function may execute in either cabinet.
I am aware of that ADIRU incident.
:Don
@alex Siew:
“Mary Kirby (Runway Girl) tweeted on March 14th that according to more than one source, one of whom with many years in the industry, the AES had a backup battery which would allow it to ping for ‘hours’.”
Below is a twitter thread from RunwayGirl (03.14.14), which includes some interesting comments:
“Indeed…but I’ve heard (from more than one source) that a back-up battery could also be in play.”
“Enough to ping for hours, says source who has been closely involved with this part of the industry for many years.”
And, she also mentions SITA (as did Stéphane Berthomet)
https://twitter.com/RunwayGirl/status/444665681532157952
Nihonmama:
How many times are we going to see this rubbish about battery backup in the AES before people stop dragging it up? The AES has no battery backup. None. We have been all over that dozens of times. Please stop bringing it back up.
@nihonmama and @airlandseaman: At the time that Mary Kirby made the statement, it was a week after the disappearance and there were many false statements made. I suspect the possibility of battery backup was suggested by somebody as an explanation for the 7 hours of handshakes assuming the plane crashed soon after its disappearance from civil radar. (The suggestion that the plane continued to fly was initially rejected by many, including Malaysia!) At that point, we didn’t even know which AES was installed in 9M-MRO.
We now know it was the Honeywell MCS-6000 and some of us have reviewed the maintenance and installation manuals. (I no longer have the link to the manuals.) There is no mention of battery backup. Perhaps somebody can a provide a link to one of these manuals to settle this once and for all. I have not looked at the manuals for many months.
From a system design point of view, it makes no sense to have a battery backup in the SATCOM. The B777 electrical system is designed with redundant AC busses and battery backup for critical systems. For cost, weight, and maintenance reasons, there would be no reason to have a battery backup for this specific system.
When I see a person hold onto and promote a technical theory that requires a backup battery in the AES, I begin to question the motivation and agenda of that person.
Victor & ALSM,
As Victor reiterates, on 14th March many commentators and reports concerning MH370 were still confused & ill-informed by just about every aspect concered with its loss.
Many outlets were struggling trying to deal with radar, transponders, satcoms, emergency locator transmitters, etc.
I suspect the focus of whatever conversation was being relayed second or third hand by ‘Runway Girl’ was the ELT, the emergency locator transmitter, a device that is designed to operate autonomously using its own battery power source.
It’s noteworthy that reports have been published today describing that QZ8501’s ELT has been found washed up on the coastline of the Java Sea. This again demonstrates that even RF devices specifically designed for emergency use are unlikely to be serviceable after in a crash in water. It’s evident, from the distance between tail wreckage & main fuselage locations, that QZ8501’s tail section where the ELT is fitted drifted some distance before sinking to the seabed.
:Don
@Airlandseaman:
What is your problem? Have I raise this issue on this board previously? I merely confirmed the existence of the Twitter convo Alex referenced. I didn’t bring it up – Alex posted it here last night).
@Victor:
I don’t know if Alex has an agenda or not. I posted it here for the reason stated above. If the question has been resolved, I’m sure Jeff will delete my post.
To everyone: I apologize for failing in my gatekeeping duties; I’ve been on deadline and was concentrating on my writing. Alex was banned for specifically for wasting other people’s time over this precise fantasy, and I regret that he was able to sneak back in and waste more time with his perseveration. Please, if he comes back, just ignore him. And @nihonmama, you should know better.
@Victor, GuardedDon:
“As Victor reiterates, on 14th March many commentators and reports concerning MH370 were still confused & ill-informed by just about every aspect concered with its loss.”
RWMann: “The fact that it continued to operate suggests a non-standard power and data arrangement which has not been explained at all.”
https://twitter.com/RWMann/status/463156999354454016
@nihonmama: Bob was assuming the plane crashed around 17:30z and speculating about how the AES could continue to function. There is no non-standard power arrangement necessary if the plane was still in the air.
I agree with Jeff. Let’s stop. We are comparing speculation made in the wake of the disappearance with hard facts about the design of the MCS-6000. When Alex has hard facts refuting what we know about the MCS-6000, we can open the debate again.
@Jeff: perhaps a “what we currently feel should be rejected, and why” sub-section in your “what we now know” compendium of knowledge might be a useful reference for those of us who are not expert in every now-ancient topic. I for one would carefully review such a sub-section before flapping my gums.
All I ask is that any such rejections stand by themselves, i.e. we’re not rejecting this simply because it conflicts with other (now-questionable) evidence.
For the record: I have never supported Mr. Siew’s theory that the signal data is valid, yet 370 crashed in the SCS. If 370 crashed in the SCS (certainly plausible, given McKay, Vietnamese reports, Chinese satellite imagery, Pinckney gag order, etc., etc.), it is FAR more likely that the signal data was simply faked (certainly plausible, given the 2-month delay in producing details, pdf format, redactions, subsequent smudging of key elements, zero surface debris at its indicated terminus, etc., etc.).
But I find it curious this topic is universally deemed by the IG to be a colossal “asked-and-answered” waste of time, despite apparently still being a manual reference short of a definitive rebuttal.
@Brock, I think a simple rule of thumb would be: if it doesn’t hit the ping rings, it’s not a good scenario.
Exceptions will be made in cases in which you can explicitly explain how the BTO data was altered.
Hi Brock,
Crash in SCS ‘plausible’?
And if true, signal data faked ‘plausible’?
Credit due for keeping an open mind, but I think I would substitute ‘highly unlikely’ for plausible in both cases.
For someone concerned about lack of discovered surface debris, a SCS crash would be much harder to explain. The SIO location is perhaps one of few crash sites where an absence of discovered debris after almost a year is truly plausible (in my opinion).
And Inmarsat did not have 2 months to fake up some data. Data retrieval and initial analysis was rapid, and data apparently shared with the U.S. and Malaysia within 5 days of the crash already indicated the length of time that the plane flew on, and a probable terminal location in the SIO. Within two weeks the doppler story had emerged in a form still recognisable today, with embedded subtleties like re-boots, eclipse effects, and a partial handshake consistent with fuel exhaustion and rapid descent.
I find the idea that Inmarsat faked the data laughable. Do we have to see demons everywhere? These are people like you and me, who did the best job they could, quickly, under intense and for them unprecedented pressure. They are justifiably proud of their work as their published paper indicates. If the plane is found near the 7th arc I hope they get the recognition they deserve.
Speaking of Inmarsat:
@MikeChillit TL is getting very interesting:
“Issues have come up about 3-F1’s actual position on March 8
It the wrong coordinates have been used for 3-F1, neither the search area nor #MH370’s final position are where they have been depicted.
Where was the satellite when it knew where #MH370 was located?”
@nihonmama: The ATSB used Inmarsat data to estimate the position of the satellite. Their results should therefore agree closely.
To prove this, I took the X,Y,Z (ECEF) coordinates from the ATSB report and converted to geodetic latitude, longitude, altitude coordinates. I then plotted those results against the orbit shown in the Inmarsat paper.
The agreement, as expected, is excellent. The blue circles (ATSB) and red squares (Inmarsat) don’t exactly coincide because the ATSB data is from slightly different times than the ping times that Inmarsat used. But all points fall exactly on the same subsatellite orbit path.
https://twitter.com/RadiantPhysics/status/562350352641830912
I replied to @MikeChillit with this result on Twitter. I suggested that perhaps he did the conversion from the ECEF coordinates to the geodetic coordinates incorrectly. (This is not as trivial as it might seem.) He decided to block me rather than respond.
@Jeff: I’d have supported your rule of thumb back when the physical evidence had not yet called those ping rings into question.
It now does.
But point taken; before claiming anything stronger than the PLAUSIBILITY of faked Inmarsat data (including the faking of any and all “decoder rings” supplied after the fact to help turn raw data into actual arcs), I will be sure to have first developed compelling evidence for means, motive, and opportunity.
In the meantime, let’s please band together and do what we can to spur public demand for the accountability NoK were promised. Once officials have turned their data and models inside out for us, we’ll all be in a much better position to judge your rule of thumb’s appropriateness.
In such pursuit, I personally think the revised “Investigate the Investigators” report currently circulating within sub-components of the IG puts our collective best foot forward – but welcome all suggested alternatives.
Hi,concerning the possible vhf radio contact at 1:30 between mh88 and mh370 I feel obliged to react. For two planes flighing both at 10k meters the line of sight distance is roughly double the normal radio horizon distance. So why is it technically impossible to cover 500km distance? I would like to hear more details in terms of transmitter power, antenna characteristics before I accept this as a fact.
The report in original NST article is very detailed in citation of the pilot who thought he established contact. I don’t think this story was made up. Anyway for a good research journalist it should not be too difficult to find out who was the pilot on the plane to Narita that night, so the story could be verified in stead of being rejected on arbitrary grounds.
@Nihonmama, @Victor: I read that twitter convo, Victor, and felt your pain. In your stead, I’ll do my best to try to work with Mike to find some common ground on both precision and priorities (2 things which seem to have drifted).
Hard to knock a guy who, by all appearances, is paying for a valuable service himself, and then doing his level best to share it with the world. (Weird that no one else on the planet seems to be doing this.) I only intervened when he started making accusations of search bias based on what was (to me) clearly an artefact of his own imprecision. (If I ever do this, please tell me – I promise not to block you!)
@Brock: Thank you. Yes, @MikeChillit is doing a great service by keeping us up to date on the search. However, he is trying to do precise calculations without fully understanding the nuances. And the Inmarsat final position on which he is basing his arc is only listed to the nearest tenth of a degree, which is relatively imprecise. Ten months ago, I might have made a lot of the same mistakes. But we have all learned so much since then.
And yes, I followed your tweets about the shifting bathy tracks with interest.
Niels
Thanks for your comments concerning the alleged report of VHF radio communications with MH370 carried at NST, published on 9th March/12:13pm
( www2.nst.com.my nation/general/font-color-red-missing-mh370-font-pilot-i-established-contact-with-plane-1.503464 )
The B777 is equipped with 3 VHF radios each with its own antenna. The ‘R’ VHF radio is normally tuned for air-air and emergency channels. I’m sure you understand the radio transmissions are broadcast on a common frequency and SELCAL isn’t possible from the aircraft so, assuming the called aircraft is in range, its identity can only be confirmed by a positive voice acknowledgement. Google for “VHF-920 data sheet”, output pwr is spec’ed at 25W, typical range for gnd stn to aircraft at 30,000ft is aprx 250mls.
Antenna detail: imgur.com/XXdmYUB
The NST report describes no conversation, attributes no flight ID to the calling party (only that it was another B777 pilot) and no other crew or ground station reported overhearing the alleged exchange. Further, the alleged time of the contact, just after 1:30am MYT is inconsistent with Malaysia’s Preliminary Report & its annex detailing recorded conversations between Lumpur Area Control and HCM Area Control: HCM Area Control first queried Lumpur ACC at 01:38 MYT for MH370’s status & at 01:57 MYT stated no contact had been made by any aircraft in the vicinity.
The NST report doesn’t imbue confidence for its veracity.
:Don
Victor, Brock, others
It is a shame Mike Chillit chooses to block everyone that points out errors in his calculations or assumptions, rather than engaging in a healthy, constructive conversation. I even sent Mike some information via pvt email, before commenting on Twitter, in the hope that he would understand his errors and correct them, with no on-line embarrassment. But there was no response, except to block me.
The unvarnished truth is that Mike’s recent obsession with the sub-satellite point track shows that he has a very confused understanding of orbit dynamics in general, and the engineering language, the facts and the sources of reliable data. (For example, referring to the sub satellite point track as the sub orbit tells me he does not know what he is talking about.) And indeed, he doesn’t understand the sub satellite point track at all. His assertion that the Inmarsat, ATSB and IG satellite locations at 001929, all of which are in close agreement, are all wrong, and his is right, is simply absurd. The TLE data has been publically available since March 8th for the world to see. Minor effects of the orbit maneuver on the previous day are easy to accommodate by using the March 9 orbits and back propagating in STK or a similar software program. Dozens of educated, skilled people have replicated the Inmarsat results. They are correct and his position is wrong. He should check his work more carefully before embarrassing himself with bogus claims, and stop blocking people that attempt to help him understand what is going on.
@Nihonmama, all
…again, I know, excuse me;
pls, what you think about this (entire) interview and the final section?
https://www.youtube.com/watch?v=CkznxGuINyk#t=1472
(war)game around? future? climate? changes?
Along with Brock’s call for alternatives and GuardedDon’s review of the possability of MH370 flying
in the Strait of Malacca being low (or none)
I will repeat that I believe MH370 didnt fly far from IGARI but crashed nearby. In addition new analysis actually supports this:
https://www.dropbox.com/s/xaki0cehauobpgr/MH370%20Flight%20Equator%20Gulf%20of%20Thailand%20Abbreviated%20Version.pdf?dl=0
Please read with open minds
Myron,
You have misunderstood me, I do not attribute the possibility that 9M-MRO continued out over the Str of Malacca as low. Rather the opposite: the Thai derived RADAR data correlates with time, flying speed & the course taken is repeatable as FMS legs.
The attachment….. stunning?
The following graph shows the ADS-B Flight Track of flight 8501:
https://www.dropbox.com/s/tpvugtfx86cyb4y/AWQ8501FltTrk.jpg?dl=0
Don,
Many thanks for your reaction. Is it correct that the estimated 250 mile range is limited by geometrical effects (curvature of earth surface)rather than by power? For air-to-air communication a different range would apply as compared to air-to-ground communication.
I agree that the reported timing of possible exchange in the NST article (shortly after 1:30 am) does not correspond with the timeline in the preliminary report about Lumpur and HCM ACC exchanges, however as with every witness report the accuracy of the reported time of alleged contact is not known. IMO the only way to conclude something on this story is to find back the pilot and ask.
Concerning the aircraft ID there are enough details given to deduce that the story refers to either MH88 or JAL750 (bound for Narita, about half an hour ahead of MH370, over Vietnam). Most people, including myself, after replaying flighradar concluded it should have been MH88, probably based on the aircraft type reported.
Now I also agree it does not make sense to keep on speculating on this report.
So I will dig into this by contacting JAL (to find out which aircraft they operated that night) and by trying to find out who was the captain on MH88 that night, (realizing this latter step is a challenge)
The point is we have so few clues on what happened that IMO we should carefully trace every piece there is.
Niels.
@Don: the radar source as discussed is inconsistent thus unreliable and even was discounted by Malaysia. Also what Thai Radar tracks mh370 from IGARI to Penang?
Don,
Thanks for your comments.
I have done a quick check whether my though about the magnetic heading from ~17:30 to Penang is correct or not (using my old “magnetic heading” model vs digitized ATSB curve). I should admit the curvature of the “magnetic heading trajectory” appears to be so small, that it hardly justifies the curvature of the trajectory presented in the ATSB report. I guess ATSB + Malaysians are due to explain what they presented.
With regard to your analysis of the radar data, an interesting, but probably useless observation, is that if MH370 flew directly from IGARI to MEKAR, it would fly virtually over RTADS-III_Khok_Muang, which was functional at that time, if your hypothesis is correct. Instead it flew close to Malay RMAF Sqdn 310, which was off. This immediately triggers “a conspiracy thought” that somebody knew that RMAF Sqdn 310 radar was off, while RTADS-III_Khok_Muang was on. This is to my earlier question with regard to Penang & Langkawi.
On the technical side. Can engine failure or mechanical wing failure, followed by a short circuit, result in the loss of primary AES power? In other words, what type of mechanical failures could knock out AES, if it was not done on purpose?
With regard to yours “if one overlays a cruise speed turn, initiated near IGARI, onto that map then its accuracy is immediately questionable”, I should note that this statement can be turned into other way: “if one overlays a cruise speed turn, initiated near IGARI, onto that map then the cruise mode of the flight is immediately questionable”. Am I right?
Here is one more nail in the 1730 emergency call coffin:
The maximum range for voice communications between two aircraft may be limited by (1) the distance to the radio horizon, or (2) available TX power and path losses. For typical VHF radios, the TX power and path losses are not the limiting factor. In fact, the free space range for a 20 dB signal to noise ratio is > 5,000 miles. Therefore, we can be certain that TX power would not limit the range to a distance less than the radio horizon limited range. The radio horizon limited range is 504 SM for two aircraft at 35,000 feet. At this range, the S/N = 40.3 dB (very good). If the distance between two planes was only 250 SM (30 min * 500mph), then the S/N would be 46 dB (even better). With a 46 dB S/N ratio, the communications would be close to “high fidelity”, not “garbled” or obscured by “static” (kTB Noise).
Fugro Supporter seems (I stress the “seems”) to be searching WELL west of anything thus far searched:
https://twitter.com/MikeChillit/status/562650317385662464
If so, this is highly pertinent information.
If anyone has the time & ability to extract accurate coordinate information from that chart, it would be greatly appreciated.
Niels,
I can’t confirm the characteristics of VHF propogation range: you asked for antenna & RF power info & I pointed you in the direction of same. I am familiar with the SITA & ARINC VHF Remote Ground Station coverage maps & they expect to provide approx 250nm radius of coverage.
We agree that the NST article, the only report I can locate regarding an air-to-air VHF radio contact, is lacking in important credible facts:
No confirmation of intelligible response from the called party that could be construed as a conversation;
No confirmed identity of the calling crew by airline, flight ID or crew member;
No corroboration of the radio broadcast being received on the open frequency by any other receiver;
Inconsistent with MoT/M published timeline for inter-ATC communications and actions (a verified air-air contact would contradict those actions).
I look forward to your findings.
:Don
Oleksandr,
You decide on a route IGARI to MEKAR, you decide on what available evidence it will be consistent with. It’s the track depicted in the Beijing Lido RADAR image and 18:22 at (MEKAR + 10nm on N571), or not.
To AES & “failure modes”: 9M-MRO’s AES comprised 9 separately powered + 6 passive LRUs. I don’t understand how I could speculate on a failure for you. To gainfully contribute you have some understanding of this yourself?
IGARI turn & progress to MEKAR: it’s my opinion that the depiction of a realistic turn on ‘fig 2’ would have quickly raised a chorus of, “WTF, really? If it wasn’t spotted in real-time, it took how many days to spot that on RADAR playback?”
A route IGARI to Penang Island & intercepting the path depicted by the RADAR targets doesn’t break the stopwatch.
:Don
Rough Estimate for Supporter from graphics:
-41.957054°, 79.664334°
Hi all. I have a question directed at Mike and Victor. I’ve asked it before but I don’t believe it was ever answered. Jeff – if I’m off topic, please let me know.
The question goes towards the BTOs. Not necessarily the validity, but the interpretation.
As I understand, signals are sent in a block of time in order to prevent collisions.
Next, I believe, but I’m not sure, that the BTO is the time between the block boundary and the actual receipt of the signal. My understanding is that it is not a true round-trip time, but it is equivalent.
Is that accurate?
If so, my real question is this:
What is the possibility that some of the BTOs are off by exactly one block size? In other words, what if the BTOs are truncated but otherwise real? This would have the effect of misleading the search.
In computer logs, in my experience, it is fairly common to encounter time stamps that are off by a time zone. Other mistakes are possible – for example using a Unix time instead of an Apple time will yield a date off by 30 years. Truncation is a relatively common problem in non-critical data because log data doesn’t always get the same level of QC that the core functionality gets.
It’s also easy enough for a human to make incorrect assumptions about logged values in an attempt to clean up the data. It’s akin to looking at the odometer of an old car and assuming it has 90k miles on it when it really has 190k.
So, I ask because if the block sizes are small enough, the data could be perfectly valid but misinterpreted.
JS:
All the BTO and BFO values are measured by Square Peg frequency agile Channel Units located at the Perth GES. All BTO values are complete round trip delay times (less a constant bias term subtracted in real-time for convenience of data logging). There is no possibility of packet collisions on the packets used to measure delay. The bias is easily calibrated using ground truth data at KL. Many have now demonstrated this, and all the results agree closely with ATSB and Inmarsat calculations (bias = ~ -495,679 usec). (See derivation of range distance and bias calibration here: https://www.dropbox.com/s/e2ij54k8voxdej8/Deriving%20Net%20L%20band%20Propagation%20Delay.pdf?dl=0
There are many questions about other aspects of the disappearance of MH370 that deserve vigorous, ongoing research. But the accuracy and interpretation of the BTO data is perhaps the only thing that is solid, factual and not worth revisiting anytime soon.
@Benaiahu: Thanks! And wow.
Still might be nothing (it’s smack dab on top of a fracture line, which raises the possibility of manganese nodule prospecting) – I have a message in to Mike Chillit asking for speed and bearing.
https://twitter.com/MikeChillit/status/562698945668083715
Speed: 3 – 4.2 kts (varied). Last bearing: SW. Appears to be settling in to a fracture zone.
May still be outrunning a storm, but seems unlikely to me.
To someone yesterday:
“If you sum it all up to date: Because of FPDA, AUS missed MH370 too. Why? (ignore); SING also must have MIL radar (silent); Indonesia must have seen/tracked (but say they didn’t); Malaysia just lied.”
SMH 3.19.14 Missing Malaysia Airlines plane: plea to US to release Pine Gap data
“Malaysia believes data from US spy satellites monitored in Australia could help find missing Malaysia Airlines flight MH370 but the information is being withheld.”
The Malaysian Insider 03.26.14
(Quoting retired BA pilot Eric Moody — from 03.24.14 Daily Mail By Richard Shears for MailOnline and Amanda Williams and Ted Thornhill and Chris Greenwood)
“What I will say is that some agency knows something more than what they are letting on and I have experience in this.
“It took 11 years to find out how Boeing was able to ring a ground engineer in Jakarta who got to us after about 15 to 20 minutes after landing.
“A phone call was made just when my engines started going wrong. It meant they knew what was going on as they were monitoring us on satellites.
“Satellite monitoring stations by Alice Springs [Read: Pine Gap] and Guam were following us as we found out from declassified files years later.”
Don,
Thanks.
With regard to IGARI->MEKAR section, I think you a bit misunderstood me. I don’t question data (yet). I question theories, and assumption within these theories, particularly AP as it stands. Reason: this affects flight mode after 19:41, as well as position at 19:41 arc. I have to remind that a single FMT between 19:25-19:40 has no grounds; it is an assumption within AP hypothesis. FMT could happen 30 minutes later – another AP trajectory would still fit BTO & BFO, with similar residuals.
Specifically, my concern was about a reason/motive/purpose to fly via Penang instead of via Langkawi, assuming that the radar data are correct and there was an interim purpose to get to MEKAR:
1. A straight path is shorter, which would be an advantage if a purpose was to get to the Indian Ocean.
2. A trajectory could also cross similar zig-zag border between Thailand and Malaysia.
3. Langkawi airport could also be used to mimic approach instead of Penang.
4. MH370 did not fly exactly over FIR boundary at the eastern approach to Malay Peninsula; it could be done more accurately if it was a purpose.
5. Same with regard to any commercial route.
6. It would enter Thai airspace for a short time, hardly sufficient for Thai military to understand what was going on and launch interceptors.
It happened that the report, link to which was provided earlier by Dennis, proposed exactly this path, via Langkawi. It turned to be erroneous (if radar data is not faked indeed), but it demonstrates a logical path if a one wished to get to the Indian Ocean. I came to the same conclusion independently.
So why did MH370 fly to Penang first? So far I can find only 2 explanations:
1. An original intent immediately after some event at ~17:22 was different, but something again happened at Penang (~18:00). Possibly this something was followed by powering up AES at 18:25.
2. There are some military installations in Thailand on the straight path IGARI->MEKAR, and the purpose was to stay away. This installation could be RTADS-III_Khok_Muan.
What else?
Nihonmama :
“It took 11 years to find out how Boeing was able to ring a ground engineer in Jakarta who got to us after about 15 to 20 minutes after landing.
A phone call was made just when my engines started going wrong. It meant they knew what was going on as they were monitoring us on satellites.”
I think this story has become distorted, misinterpreted and embellished, to the point that it is now an “old wife’s tale”.
There is nothing unusual or sinister about engine monitoring in this fashion, and it is not carried out by some nebulous, unknown satellites operated by some foreign agency. It is in fact a normal monitoring function, I think using ACARS to transport operational messages of this type.
A B777 captain friend commented to me that he has had, more than once, a call from operations before even taxiing out to line up, saying that “we didn’t like the way the engine started up that time. Please shut down and try again”. All perfectly normal operating procedures – – – as long as ACARS is operational.
@ALSM – I’m not necessarily suggesting the data is wrong, but I’m not sure it can be settled, either, or that there aren’t alternate interpretations of it.
I’d still have to disagree that the 17 ground truth datapoints correlate to the location well enough to use that calibration for the rest of the flight. However, that said, I’m not sure it would change anything – perhaps it’s off by a few km.
But let’s focus on packet collisions. In your response, you say there is no possibility of a packet collision. Can you explain how this works? We have shifting frequencies and delayed signals – how does the system account for this so that two signals don’t arrive simultaneously on the same frequency? How big are the separations in relation to the expected BFOs? Does the AES immediately respond to the satelite’s query, or does it wait for a specific time slot?
I’m shaking the tree here and not trying to go down a rabbit hole, but I’m curious to know if there is any way a signal’s time could be logged improperly. In the grand scheme of things, such an error would seem to be more probable than a spoof, but less probable than the BTO being good data. That middle probability seems worthy of some discussion.
@Flitzer_Flyer:
“There is nothing unusual or sinister about engine monitoring in this fashion”
Is that why I posted the article?
Don,
With regard to a possible mechanical failure, I am looking for an answer, whether mechanical failure of a wing/engine could cause a short circuit that knocked out AES and a number of other systems. Unfortunately I am not a specialist in the design of electrical systems of aircrafts (math and physics are my passion), thus I have to rely on the expertise of specialists in this fields. What I am looking specifically for, is analogy with ELAL_1862, Qantas_32, JAL_123:
en.wikipedia.org/wiki/El_Al_Flight_1862
en.wikipedia.org/wiki/Qantas_Flight_32
en.wikipedia.org/wiki/Japan_Airlines_Flight_123
An interesting feature about 1862 was that air crash investigators concluded that the aircraft could stay in the air at high airspeed, but the lift became insufficient at low speeds (<500 kph) making landing impossible. Could something similar be a reason for MH370 to turn westward at Penang when the crew discovered they were not be able to land safely in KLIA, or Penang?
Now recall that the right wing of MH370 was substantially damaged in Shanghai. Another JAL123?
The only missing piece in this theory is how wing/engine failure could knock out electronics.
@Oleksandr :
“So why did MH370 fly to Penang first? So far I can find only 2 explanations:”
3.) Cpt. Shah was born in Penang. Maybe he had some reasons to fly over his city where he lived in his early stages of his life until he moved to Shah Alam, Selangor in Kuala Lumpur ?
JS,
The only chance for packet collision is on the R channel from the AES to GES. If a collision occurs the GES fails to decode anything from either simultaneously transmitted burst, neither AES receives its due response so backs off for a randomised period & retries.
All AES R & T chl transmissions are sync’ed to receipt of the continuously transmitted P ch frames from the GES.
Datacomms protocols aren’t subject to interpretation: they are very rigid, tightly defined systems. The word protocol is a clue.
:Don
Oleksandr,
OK, I understand your premise now.
Still, it’s nigh-on impossible to speculate a chain of events as you suggest.
We do believe the aircraft is still flying an hour after some event that brought about the deviation. Exercising your line of thought, following a non-catastrophic (plane still flying) issue, would one not expect a communication. The aircraft has 5 separate means of voice comm: 3x VHF, 1x HF & SATCOM. The VHF radios are under his seat in the MEC with one antenna above his head & the other on the aircraft belly; the remaining systems rely on, at least, antennas aft of the wings.
Langkawi’s closed at night. A leg to Penang follows an established airway, straight to MEKAR doesn’t, if the intent is seeding confusion but not alarm then Penang’s good.
:Don