Today I’d like to discuss some of the implications of what DSTG scientist Neil Gordon said in the course of the interview I published yesterday.
In particular, I’d like to look at what he told me about the ATSB’s interpretation of the 0:19:37 BFO value. Essentially, Gordon assures us that the experts have looked at what the manufacturers know about how these boxes work, and the only interpretation they can come up with is that the BFO value was the result of a very steep rate of descent–specifically, 5,000 fpm at 00:19:29 and then 12,000 to 20,000 fpm at 00:19:37. This is got a gentle deterioration; it’s accelerating at about 1/2 g, so that in another 8 seconds, at that rate, the descent will be at 19,000 to 35,000 fpm, that is to say going straight down at 187 to 345 knots. Remember that the plane had already been losing speed and altitude for five to fifteen minutes before the second engine even flamed out, and losing more altitude in the subsequent two minutes before the 00:19:29 ping was logged. Thus, both velocity and acceleration point to a situation in which the plane will be hitting the surface in short order. Bearing in mind that the plane would be in a spiral dive if unpiloted, I can’t see how it could have traveled more than 5 nm from the last ping, let alone 15nm, let alone 40 nm. It would have hit soon, and it would have hit hard.
One possible explanation would be the idea that the plane was in a phugoid: plunging quickly, then rising again, then plunging again. But as I wrote in a previous post, simulator runs by Mike Exner suggest that these extreme rates of descent are characteristic of the later stages of an unpiloted post-flameout plunge, when phugoid effects are overwhelmed. Thus, if the ATSB is correct in interpreting the final BFO value as a very steep plunge–as Gordon assures us they must–then the plane should be well within 15 nautical miles of the seventh arc.
The chart above (based on the invaluable work of Richard Cole) shows a band of seabed, marked in red, defined by an outer border that is 15 nm beyond the 7th arc and an inner border that is 15 within the 7th arc. As you can see, this band has almost entirely been searched out to the 99% confidence level as defined in Figure 2 of my previous post (located at the intersection of the 7th arc and 94.85 degrees east). All that remains is a rectangle approximately 17 km wide and 150 km long, for a total area of 2,550 sq km.
According to Figure 3 in that same post, the DST calculates that the probability that the plane crossed the seventh arc northeastward of 96.75 degrees east longitude is effectively zero. To search to this longitude would require covering another 3,700 or so sq km. Thus, to cover all the seabed that MH370 could plausibly have reached, if the ATSB’s BTO and BFO analysis is correct, would require another 6,250 sq km of seabed scanning, which is more or less what the ATSB has been planning to search anyway. Unfortunately, the search at present is not taking place in either of these remaining areas.
As I see it, there are four possibilities at this juncture:
- Both the BFO and the BTO analysis are correct, and the plane is lying somewhere in the remaining 6,250 sq km described above.
- The BTO analysis is correct, but the BFO analysis is wrong. In this case, the plane was not necessarily descending with great rapidity, and instead might have been held in a glide, and is most likely in “Area 1” shown above.
- The BTO analysis is incorrect, and the BFO analysis is correct. The plane was indeed descending very rapidly during the last ping, but the plane was further to the northeast somewhere in “Area 2.”
- Both BTO and BFO analysis are incorrect. The plane could be just about anywhere.
I happen to believe that the DSTG knows what it is doing, and that 2 through 4 are not the case. On the other hand, the unsearched areas remaining are at the far fringes of likelihood, and so don’t feel that #1 is a high-probability option, either. No doubt some will argue that the plane might have been overlooked within the area already searched, despite assurances from officials that if it was there they would have seen it.
Frankly, we’re running out of compelling options.
Exner’s simulation ended in 6.5 g. Overload was discussed here on this blog, with David and Brian Anderson.
@Sinux, Gysbreght, Rob. The two BFO descent rates. Gysbreght from memory you raised the instance of an autopilot malfunction causing pitch down to minus 1g in 1.8 seconds. As you implied it is not just the vertical component of gravity acceleration which counts in this but pitch down also, with or without bank. From my calculations a pitch down from 5000 fpm ROD to 12000 or 20000 is quite easily done, the former requiring a bunt, wings level to around 1/2 g +ve, in the same 1.8 secs, to get to more than 12000 fpm in the 8 secs total. To get to 20,000, zero g would suffice.
I mean these figures to be indicative since they rely on a heap of approximations; but I have confidence in them broadly being appropriate.
With serious bank the whole thing changes and I have not been into that.
Gysbreght you have said also that without a pilot this could not happen. Using your Exner simulator model you note that the down phase of a phugoid would be needed to even get to the first BFO’s 5000 fpm descent. However this depends on the pertinence of that simulation. An instance where the Boeing tests, at least those most recent, yield a quite different descent profile to the Exner simulation is the latter being notable gentle in mean descent for some minutes after FE. Apparently the Boeing simulation says the rapid change from 5000 can happen fast. Maybe bank intrudes. They have not said, though certainly it is a very different stance than formerly.
I think it reasonable to assume they will have grounds.
Another point please. From whence do these limits of 12000 and 20000 for the second BFO derive? If the BFO have been substantiated by SDU testing as Dr Gordon says why this tolerance?
He has reminded that the southerly heading can be traded for a descent and has said they have tried reversals, “Let’s imagine that everything was the worst case, pushing the BFO in the opposite direction to disavow a descent, what if it had turned back the other way and it’s going completely the opposite direction….”(the unfiltered interview). What I take it he means is that they have established that were the aircraft on a northerly heading part of a spiral at the second BFO it still would have a substantial descent rate, leading to the 12000, the 20000 being set by a southerly direction. Or at least that would be a major contributor. I believe this difference to be greater than a phugoid up/down of itself would account for, at least that of the Exner simulation.
I hope he took account of the point Lauren H made as to the SDU getting cold if the aircraft were depressurised, probably related to the much discussed fig 5.4. DennisW reinforced that the oscillator will be sensitive to temperature. (btw, depressurisation due to turning off engine bleed air should save fuel since engine air bleed is very inefficient, or used to be once).
@Jeff Wise. ““The damage was not from flutter. It was overload. It pulled 5.1g. See the report 1.12 and just above.” Apologies, to which report are you referring?
Ge Rijn referred to this Jeff.
http://www.rvs.uni-bielefeld.de/publications/Incidents/DOCS/ComAndRep/ChinaAir/AAR8603.html
@Gysbreght
Fair enough we don’t know if the BFO is reliable. It would be nice if Neil would be able to give us more information about what boeing found (how much uncertainty on that BFO measurment).
But we have to start somewhere, and that’s why I only took the lower limit mentioned by Jeff.
Regarding “2min is a good time to have -5000FPM”. It is. Although it’s not quite -5000FPM on your graph. But the main problem is that 3min36 sec after flame out in your graph, the plane is close to 0FPM! At that time the IFE logon is expected. It doesn’t happen… the official explanation is : The plane has crashed by that time.
In the sim it takes an extra 4 min after IFE logon to crash…
So is the sim accurate?
Or does the ATSB have the flame out time wrong and the APU start time wrong by 4min at least?
When I first posted about that point, I was imagining that the BFO were taken some time between 11min and 12min (in your graph). This is why I suggested moving the plane a bit more north on the arc to reduce the BFOs so that it would match the acceleration observed in the sim.
But you are right to point out that these occured much earlier!
What’s your take on that?
@David:
For the record, it was not an autopilot malfunction. For reasons that have never been found, the ADIRU output erroneously produced high angle of attack values. The Flight Control computers should have detected and rejected those erroneous values, but didn’t due to a software error. Therefore the FCC’s detected a stall, and responded with 10° elevator nose-down.
I’m not sure what you mean by “the pertinence of that simulation”. A phugoid is a well defined, understood and easily quantifiable motion. I have described it earlier and could elaborate on earlier explanations if necessary. It is defined by the difference between the airplane states immediately before and after the second engine flameout. In most situations a phugoid will occur, but situations can be envisaged where it does not occur. The motion follows naturally from the equations of motion for constant angle of attack and a set of initial conditions. I didn’t have change anything in the calculation logic to produce those curves.
On the Boeing tests we only have ATSB’s account of them, which seems to have opportunistically changed recently. No new facts have been presented to justify that change of account.
@David
-1g is quite doable from flight level to pitch down. But will only last for a short time! (thus the 1.8s mentioned)
To keep the acceleration on a longer time is the problem.
Drag will not allow you to keep accelerating at 1g for long.
The plane was already descending at -5000FPM and yet it accelerated to -12000FPM in 8sec that’s a different thing.
Not easy to explain if the plane was unpowered and unpiloted.
@Gysbreght
Regarding my previous post :
If the sim that you’ve graphed is representative and the timings are right, the plane could only drop about 7500feet before the IFE logon should have registered. IE the plane was flying lower than that!
@Jeff: I expected as much but it is good to have it off the table, for me. Thxx.
@Jeff Wise @David @others
To read easily for all I copied the relevant part of the report.
Interesting to me is also the only empenage damage was to the APU. It seems to have broken from its mountings probably rendering it useless. Could this have end the APU’s operation in stead of fuel exhaustion in MH370 too?
1.12 Wreckage and Impact Information
“All the damage found on the airplane occurred during the descent and was caused by aerodynamic overload forces”.
Wings and Engine Pylons.
–The wings were bent or set permanently 2 to 3 inches upward at the wingtips; however, the set was within the manufacturer’s allowable tolerances. The left outboard aileron’s upper surface panel was broken and the trailing edge wedge was cracked in several places.
Wing and Body Landing Gear.–The left and right wing landing gear uplock assemblies had separated from their attachment points on the fuselage structure. The interior skin and associated ribs on the left and right wing gear inboard doors were damaged in the vicinity of their striker plates and the striker plates also were damaged.
-13-
The doors were damaged in the area where the tires are located when the gears are retracted.
The left and right body landing gear uplock hooks were found in the locked-up position, but the fasteners of their uplock support bracket assemblies had failed at the attach points to the fuselage bulkhead.
The left and right body gear actuator doors had separated, but the forward lateral beams and associated door actuators had remained attached to their respective assemblies, and there were tire marks on the sections of structure attached to the lateral beams. (Note: The uplock assemblies hold the body gear in the retracted position after gear retraction is completed. Except for the body gear tilt assembly, which is pressurized by the No. 1 hydraulic system, the body gear actuators are unpressurized. The tilt assembly is pressurized and remains pressurized so that the body gear wheel bogies can enter or leave their wheel wells without their tires striking the forward wheel well structure.)
Empennage.–The major damage to the empennage was limited to the Auxiliary Unit APU) compartment, the horizontal stabilizers, and elevators. The APU had separated from its mounts and was resting on the two lower tail cone access doors. The forward side of the APU fire bulkhead appeared to be deflected forward in the area adjacent to the two lower attachment fittings and the two lower support rods had buckled. In the area of the APU, there were several punctures in an outward direction on both sides of the tail cone”.
@sinux:
“At that time the IFE logon is expected. It doesn’t happen… the official explanation is : The plane has crashed by that time.”
That only one of several possibilities. Another explanation is that the APU had exhausted the very limited amount of fuel available to it.
“So is the sim accurate?”. I don’t think that simulator accuracy is a big issue. My modeling of Exner’s simulation assumes a moderate angle of attack, no sideslip, and stays well below Mmo. Within those limits approved pilot training are quite accurate. Perhaps they do not accurately reflect the deformation of the airframe under loads that exceed the operating envelope, or structural failure under those loads. We do not know in detail how the simulator was set up and managed during the tests. I have stated repeatedly that I consider the rudder trim to be excessive, and that therefore the simulation is likely to be not representative for the real airplane.
“What’s your take on that?” Sorry, I don’t quite understand your question.
@Sinux
@Gysbreght
Sinux, the IFE logon not taking place could have been due to the IFE/seat power switch having been selected off, some time after the first logon (the 18:25 logon).
I don’t think there is a official reason for the lack of an IFE logon after the 00:19 logon.
Sorry, that should have been: Within those limits approved pilot training simulators are quite accurate.
@ROB
From memory I recall the ATSB also stated the missing IFE-log-on could also have happened due to a power switch-off to the IFE from the cockpit before 0:19.
Would take time to find that statement by me but probably you or another has this information at hand.
@Gysbreght. I was referring to the continuing relevance of the Exner simulation, not the phugoid in particular, though Boeing might have found a different amplitude with bank for example when combined with stick fixed to free and so on…
As you say the simulator might not reflect the real thing as you say and that no-one will be replicating to extremis such as high g so perhaps it is wind tunnel work and analysis.
@Sinux. What I assessed was holding the g at 1.8 secs for another 6.2. Yes, this would assume a pilot unless Boeing has discovered rapid bank or other.
Not easy at all to explain that and who knows how long it might be before we learn. I have raised this in part because earlier I had dwelt on downwards acceleration and the difficulties if that were the criterion whereas change of direction of the velocity vector downwards is the “driver”. I felt that the comparatively modest 1/2 or zero g was worth raising and might lessen the challenge. Belief in the ATSB account of Boeing’s test results is a judgement but I would have thought that the Gordon interview would increase confidence despite motivation having been favoured over statistics in some quarters.
@Gysbreght
…given the unknowns in the phugoid calculations, do you think it is possible for the aircraft to begin another “nose-up” cycle near the water surface (impact)?
@Ge Rijn. Worthwhile posting the damage as you have. It says somewhere the aircraft did not exceed Vmo.
The APU being displaced/stopped by high g would be a factor in IFE non-connect if the high g occurred within one and a half minutes of the second BFO. However aside from the other possibilities raised there is loss of antenna ‘lock on’ during the spiral, also mentioned by the ATSB.
Jeff Wise
Posted September 9, 2016 at 8:08 AM
@Johan, You wrote: “Could Z have known or guessed about the possibility to track the plane through the Inmarsat data?”
The answer is an unequivocal “no.”
“unequivocal”
Really ?
Read “between the lines” of Pages 17 and 18 of:-
https://www.bea.aero/enquetes/vol.af.447/triggered.transmission.of.flight.data.pdf
@TBill:
The phugoid motion is super-imposed on the overall motion defined by the increasing bank angle. At the end of Exner’s simulation the rate of descent has increased to about 20,000 fpm. The phugoid component can ‘modulate’ the overall rate of descent by about plus or minus 2000 fpm.
Can the first BFO (at 0:19:29) and concomitant rate of descent be explained with a deliberate/controlled effort to increase speed in order to prevent the aircraft from stalling?
@ventus45, Very interesting document, but I’m not sure what you’re driving at. Perhaps you could elaborate?
@Nederland: Yes, that is certainly possible. If an inexperienced ‘pilot’ was surprised by the dual flameout, it is even more than likely.
@Gysbreght
IMO the BFO values at 00:19 are too large to be explained by anything other than a high rate of descent. Even the BFO at 00:11 (using a location in the vicinity of the current search area) needs a little negative ROC to meet the BFO value. I am assuming the BFO values are accurate when making these statements.
@DennisW, you wrote, “Even the BFO at 00:11 (using a location in the vicinity of the current search area) needs a little negative ROC to meet the BFO value” I hadn’t realized that. Assuming a generally south-southeasterly heading, about what would the descent rate be?
@JW
I compute something in the neighborhood of 200 fpm negative.
@JW
Keep in mind that 200fpm is on the order of a meter/sec or on the order of 4Hz in BFO. Are the BFO values that accurate? I mean 4Hz seems pretty anal to me, but others would disagree.
@Jeff Wise @DennisW
May be silly but it reminds me of the minimal neg. RoC of 100ft/min. that could have been set in an AP-mode-scenario @Victorl once proposed as a possibility.
@DennisW, Whether or not anyone would pin their life on that particular data point, it is broadly consistent with the kind of drift-down one might expect after the first engine flamed out. Which Mike thinks happened after 0:11 (if I recall correctly) but the ATSB says might have happened before.
@DennisW: The Inmarsat paper in Journal of Navigation computes zero BFO error at 00:11:00 829kph 180° true track.
@Gysbreght
At 829kph @180 true (37S, 89W) I get a net BFO of 43.6Hz versus a published 38.5Hz. Hence, the need for -5Hz or about -1m/s ROC.
Not sure where the small difference lies. I am pretty confident of my number. Can you run it through Yap’s calculator? I have never used it myself.
@DennisW: Yap’s Calculator gives a calculated BFO of 251.79 Hz at 00:11 for the Inmarsat coordinates etc..
@Gysbreght
Oops! We are talking about two different things. I use BFO residuals. Meaning how much of the BFO needs to be attributed to aircraft position and motion. If I add back in the other contributors of BFO my value becomes 256Hz versus reported 252Hz. Sorry, I should have realized that no one else seems to do it that way.
The notion of using BFO residuals is in recognition that all other sources of BFO are fixed relative to anything the aircraft might do. So I calculate them once as a function of time, and just work with the residuals for computing flight paths.
@DennisW: Yes, I was aware of that, but I thought I could leave the conversion to ‘residuals’ to you.
@Gysbreght
In the interest of full disclosure at 00:11 I use.
BFO measured = 252Hz
Satellite => Perth = 101Hz
AES Offset = 150.6Hz
Table 4 value = 37.7Hz (geometry fudge factor)
Implies a Doppler residual of 38.1Hz. If I use the Ashton et. al. numbers for the above, the residual comes out to 39Hz. Too close to argue about. The 4Hz or so must be a difference in calculating the total aircraft Doppler – aircraft motion relative to moving satellite and the Doppler compensation of the AES.
@Gysbreght
more…
The total aircraft Doppler is computed in ECEF coordinates, so it is pretty hard to screw that up.
Link to my geometric model below (see figure):
http://tmex1.blogspot.com/2015/09/mid-flight-speed-mh370-mid-flight-speed.html
@DennisW: Here is a screengrab:
https://www.dropbox.com/s/bntgks479fj2g2j/Schermafdruk%202016-09-09%2018.56.40.png?dl=0
@Ventus45
Nobody would have guessed prior to the event, that the ISAT pings could be used to track an aircraft’s flight. After the AF447 accident, INMARSAT decided to retain the signal timing (BTO) feature, because it had proved useful in locating the impact point. They had a hunch it could be useful in the future. They were right! Utilizing the BFO to work out the direction of travel is another matter altogether. Nobody had even considered such a possibility before MH370, not even a INMARSAT. That they managed to do it was an unusual example of necessity being the mother of invention.
If Z had any inkling that handshake pings (that is if he was aware of handshake pings, which I also very much doubt) could be used to track him, he would have needed to keep the SDU switched off for the whole of the flight, and we know that he didn’t do that.
It is an interesting point, because if he assumed he couldn’t be tracked by the SATCOM transmissions, he would have considered it safe to fly a straight course following the FMT, and there is some evidence that’s exactly what he did.
I am not sure about the Inmarsat satellite phone but I know the Iridium satellite phone has a special emergency button which allows you to activate Emergency Mode and send SMS messages with your GPS position (phone build in feature) up to three contacts and/or to GEOS Travel Safety Group (geosalliance.com). The Iridium has also another feature called short burst data (SBD) which provides the ability to track your phone’s location online.
@Gysbreght
Thanks for the link. Mystery solved.
When I use 33.7S and 93E 9 (as in your link), I get exactly the same results as in your link. I was using 37.7S and 89E.
uplink Doppler -648.6Hz
AES Comp 687.3Hz
Doppler residual 38.7Hz
The world is, once again, a happy place.
@DennisW
I though something was amiss when you quoted S37, E89! I was beginning to loose my faith in human nature. 😉
@ROB
Those were the coordinates sitting in my model when I was checking out Exner’s ROC numbers. I do not personally endorse those coordinates at 00:11. Not to say I do not have the utmost respect for the people using them.
@Gysbreght
Sorry I didn’t express that question clearly. Let me rephrase:
What do you think the “real” value of the last BFO should be? Very close to the previous one? Or indicative of a dramatically (but within reason) increasing speed?
Thanks also for the explanation regarding the accuracy of the sim. Again poor choice of word on my side. I meant how representative do you think one sim can be to the real flight? Since Boeing has done many simulations, what are the spread of outcomes we can expect?
Thanks in advance!
@Sinux
Once again, speed alone cannot explain the BFO’s (if accurate). The speed, in level flight, is largely compensated by algorithms in the AES. The aircraft simply cannot fly fast enough to produce the BFO values without a very significant rate of descent. Your only options are to discard the BFO’s as invalid or acknowledge that the aircraft was descending at a very rapid rate. The numbers calculated by Exner and others are correct.
@sinux: Firstly, I have no reason to doubt Inmarsats considered judgment the the first of the 00:19 BFO’s is valid, and the second is not. Secondly, based on my understanding of airplane dynamics, I believe that only pilot inputs or control system failures can cause the rate of descent to increase that rapidly. So for me the last valid BFO is that logged at the log-on request at 00:19:29.4. There is no point in guessing what it could have been 8 seconds later, or 20 seconds, or minutes.
“how representative do you think one sim can be to the real flight? Since Boeing has done many simulations, what are the spread of outcomes we can expect?” A professional Flight Simulator, approved and certified as a substitute for the real airplane for the purpose of required training of airline pilots, can be expected to be representative to the real flight, as long as the simulation does not go outside the conditions where the aerodynamic and other characteristics of the real airplane are known from flight test and analysis.
The end result of a simulation without pilot inputs depends on the initial conditions such as altitude, airspeed, vertical speed, trim in all three axes, etc. Another variable may be in the time delays in systems operation in conditions that do not feature in any pilot training syllabus. For example, how long does it take for the APU to get on line? How accurate is the modeling of the fuel remaining available for the APU after main engine flameout? How variable is the time the SDU takes between power-on and transmitting a log-on request?
@Jeff, @ROB, @ventus45:
Giving it a second thought my questions appear strange even to myself, but what was behind the bend for me was the logon request just prior to the FMT, which reekes of a false direction marker, pointing northwest. (Which btw could be the rationale behind showing himself to potential onlookers in that region before turning south.) If you think the one you have to think the other so to speak.
I find it interesting to see that Neil Gordon assumes that Malaysia have a video recording of the radar observing MH370 rather than a digital backup of measurements. I wonder if they do regular recordings or only when necessary. The Lido picture showing the radar track only starts off Penang, whereas the FI provides single data records only. Perhaps the Lido picture indicates the start of the video recording?
How about Indonesia? According to the FI, Indonesia never forwarded any data on their radar records. Perhaps they have no digital backup either? They did, however, say that their radar on Sabang is strong, but did not detect MH370 flying into Indonesian airspace. Perhaps the radar was operational and manned, but no one followed up on the radar blip obviously because it did not enter their airspace. One spokesperson elaborated that it has been suggested that MH370 was spotted in Indian airspace (in Andaman island) and that it could be ‘very likely’ that MH370 stayed clear of Sumatra, flying north and eventually south. In that case, the Sabang radar could not have detected MH370 flying in a southerly direction (into Indonesian airspace) and, given the range of that radar, that means the FMT must have occurred after 18:40:
‘another military radar suggestion said that it was once detected in the Andaman Islands. So, it could very likely have cleared Sumatra island in the north before making another turn to the south until it was 2,500 kilometers from Perth.’
And does the statement
‘Don’t be misled by graphical illustrations and maps because our earth is not flat like those maps’
not indicate the possibility that MH370 may have flown at lower altitude, thereby reducing the radar range?
http://www.thejakartapost.com/news/2014/03/26/govt-insists-mh370-did-not-fly-indonesian-airspace.html
@Nederland
‘Don’t be misled by graphical illustrations and maps because our earth is not flat like those maps’
I put the above statement in the “blowing smoke” category. I mean how arrogant is it for a person to think all the other people in world have a third grade education? Statements like that really annoy me. What a buffoon.
Susie Crowe Sep 9th, 3:05 AM posted an article from Free Malaysia Today about Captain Zaharie’s frame of mind, some relationships and plan to move to Australia. It was drawn from an earlier article in The Australian.
However It did not include that article’s final paragraph which said, “As the MH370 search prepares to wind down, Malaysia’s National Union of Flight Attendants has again queried why a second transponder located in the cabin crew closet outside the cockpit was not triggered — or its signal picked up — after Captain Zaharie signed off from Malaysian air space and the cockpit transponder stopped transmitting.”
What are they talking about? Maybe what is meant is a cabin ELT. But if as has been supposed a signal from that would not escape the hull I would expect the cabin crew to know that. It is implied also that this would be an expected step by cabin crew, supposing they were aware of the situation. In turn, the flight deck crew would know of that.
Maybe behind paywall. I will post anyone would like.
http://www.theaustralian.com.au/business/aviation/mh370-pilot-zaharie-was-planning-to-retire-to-australia/news-story/5988d10e3d330cc2df7adb1be6335a8d
@Jeff, @ROB, @ventus45:
I think that its basic radioelectronics knowledge that there are delivery times between far remote transceiver and receiver and in case they are mobile (and very fast) that doppler effect is there to consider. So as every rock-solid system must have proper logging for diagnostics – as inmarsat has, or even better full live telemetry, its not too hard for man who likes radioelectronics and probably builds/assemble(?) their own RC planes/controllers to understand that with precise enough logging, having mandatory timing compensations of Einsteins general relativity theory on geostationary satellite and plane in some altitude too, this sat in fact behaves like “remotely controlled digital low-power space radar” against the planes, .. so it si natural that such logged info must be useable to track the plane… the more it was already used in the Air France case ?? + Zahrie may knew also about inmarsat hourly inactivity check pings; where the hourly time window was initiated by end of 1st satphone call (probably ringing into cocpit) – the last comm from ground.
Besides loss of power, loss of satellite visibility can trigger Logon requests by the SDU.
@All
For aircraft equipped with Inmarsat SatCom, the call is established at the beginning of the flight and the communication is possible as long as the satellite is visible to the antenna.
The visibility of the satellite depends on the elevation to the satellite relative to the airframe.
The relative elevation depends on aircraft’s pitch, roll, heading, latitude, and longitude and on satellite positions. As long as the relative elevation is greater than 0, the satellite is visible to the antenna.
The relative elevation can become negative as the aircraft is banking away from the satellite and visibility to the satellite is lost.
When the view of the satellite is lost, the SDU transceiver goes into ‘link outage’ mode which means that it will attempt to reacquire the link but will not drop the call. The link outage may last up to approximately 10 -11 seconds. If within 10 seconds, the link becomes available again, data transmission can resume.
After 11 seconds in ‘link outage’ mode the call will be dropped. The SatCom system will re-scan for satellite beams, establish a link, perform necessary location update, get a channel allocation and re-establish the call.
Most aircraft SatCom antennas are electronic steerable so if the ADIRU inputs are valid the SDU should be able to locate a satellite beacon signal within ~10 seconds. Call reconnection time is typically about 30 seconds.
From this we can conclude that MH370 impacted less than 30 seconds after the 0:19:29 logon request.
The either or both logons at 18:25 and 0:19 could have been triggered by airframe orientation if it blocked view of the satellite for > 11 seconds.
@David you mentioned that the article (link) posted by Suzy Crowe in freemalaysiatoday : http://www.freemalaysiatoday.com/category/nation/2016/09/09/mh370-pilot-wanted-to-settle-in-australia-says-report/
was lifted from an article in the Australian, without the paragraph included in your post above : “Malaysia’s National Union of Flight Attendants has again queried “why a second transponder located in the cabin crew closet outside the cockpit was not triggered — or its signal picked up — after Captain Zaharie signed off from Malaysian air space and the cockpit transponder stopped transmitting.”
Can be interpreted in a number of ways and should not be a footnote used to pin the rose on Z as it is open to speculation, certainly not evidence of his guilt. If anything it seems to indicate the opposite.
In the context of the Free Malaysia Today the article is about Zaharie, family, habits and addresses several of the statements spun to make him look like a political radical with suicidal motive based on political disappointment.
The article is a summary of a completely different and more rational, realistic portrayal of the actual Zaharie from people who knew him.
Since spending so much time in Malaysia over the past ten years. The corruption issue, disgruntled comments about corruption from taxi drivers, expats and the general population is countered and mostly negated by the great lifestyle people enjoy there. The dialoging about corruption is the stuff of amiable social interactions, tut tut views and no more corrupt than any other country in that region or as is increasingly the case, the West.
The ongoing struggles of Anwar Ibrahim have been playing out over an extended period, first arrested on the charge of sodomy in 1998 so if the charges and ongoing court cases were the tipping point why did it take 15 years for Zaharie to become politically bereft based on these court actions.
All of these assertions from commentators that seem to be writing an erroneous script, based on indirect hearsay, trying to profile the pilot into a behavior that was counter to what people who worked with, lived with him and knew of the man have not confirmed.
In cases like this, where the person is dead and cannot speak for themselves, where there is such a drive to spin this missing plane on an alleged suicidal pilot I ask, to whose benefit.
The benefit, usually business, political or military gain. If the finding regarding responsibility is inconclusive or if it was terrorist or military action then who pays? If it is found to be Zaharie, (aka scapegoat) the dead guy, who has the greater liability for compensation payouts? If the plane had some fault, Boeing’s insurers?
It probably suits Boeing -Lloyd’s/ Allianz that Zaharie is being accused, hence the overwhelming recent media spin in that direction.
The diagrams showing the arc being searched, south, is a less problematic a search, in the Indian ocean than if the plane was flown on the northerly arc over those countries. In that case could any search have been carried out.
How does it suit MAS, Malaysian government, Boeing and the insurance companies that the search went on for two years without a result?
There is (2 year) limitation to insurance claims under Montreal Convention.
“Families who missed the March 8 (2016) deadline to initiate lawsuits against the Malaysia Airlines may also be stranded if pilot suicide was indeed the cause of the crash, thanks to the 1999 Montreal Convention, which dictates international aviation insurance terms. Under the treaty, claimants have two years from the date an aircraft should have arrived at its destination to file suit for compensation against the carrier.
“You can’t start something now because the limitations date has passed,” Nathan told The Australian.
Nathan also pointed to the question of airline responsibility in a suicide situation.
Even if Malaysia Airlines can successfully determine the cause of the crash, aviation policies often carry exclusions for terrorism or suicide – under sanction from the Montreal Convention – which may apply here.
“If it is proven to be pilot suicide, then the insurance becomes void,” she said.”
http://www.insurancebusinessonline.com.au/au/news/breaking-news/breaking-missing-mh370-flight-may-have-deliberately-crashed-complicating-insurance-settlements-220623.aspx