Malaysian Airlines MH370 contact lost
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PS: OTOH looking at appendix 1 of the raw data again: The BFO constantly lies between 86 and 90 in the one minute interval between 18:39:55 and 18:40:56. That is indicative of either a constant descent during this minute or a southerly course. To me the latter has higher probability
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@Ole
It wasn't descending at that stage of the flight, but I believe it was headed SSW.
I have looked at the possibility of the flight having hugged the FIR boundary again and I now see that that looks very unlikely - if it did, it would have passed within 5 nm of Pulau We Island, which would have put it in Indonesian sovereign territory.
It wasn't descending at that stage of the flight, but I believe it was headed SSW.
I have looked at the possibility of the flight having hugged the FIR boundary again and I now see that that looks very unlikely - if it did, it would have passed within 5 nm of Pulau We Island, which would have put it in Indonesian sovereign territory.
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The main problem I see with the 18:40 BFO is, that it occurs in the C-Channel and not in the R-Channel as all other BFO measurements. Yet the BFO for the 23:14 ground to air call also is in the C-Channel and aligns nicely with the "neighboring" R-Channel measurements, so a big difference between R- and C-Channel BFO doesn't seem to exist. How deterministic this behavior is for this particular terminal we don't know (inmarsat probably does).
I am not aware of any substantiated report that any system on MH370 was 'shut down'. All we know was that various systems were no longer responding at certain times. We also know that the satcom was 'off' at least twice by the fact that it logged on twice. 'Off' in this sense means that the aircraft terminal was not in a logged on status (due to loosing the signal, being shut down, having power lost, etc.) but doesn't tell the reason it was 'off'.
we have a last Transponder return time, a last ACARS message time, a Last RTF time, several missed phone calls times, but not a single logoff or power down message. Nor do I believe any of those systems generate such a logoff messages.
we have a last Transponder return time, a last ACARS message time, a Last RTF time, several missed phone calls times, but not a single logoff or power down message. Nor do I believe any of those systems generate such a logoff messages.
Final words from Flight MH370 came after systems shutdown | The Japan Times
Authorities have said someone on board the plane first disabled one of its communications systems — the Aircraft and Communications Addressing and Reporting System, or ACARS — about 40 minutes after takeoff. The ACARS equipment sends information about the jet’s engines and other data to the airline.
Around 14 minutes later, the transponder that identifies the plane to commercial radar systems was also shut down. The fact that both systems went dark separately offered strong evidence that the plane’s disappearance was deliberate.
Around 14 minutes later, the transponder that identifies the plane to commercial radar systems was also shut down. The fact that both systems went dark separately offered strong evidence that the plane’s disappearance was deliberate.
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BFO value at 22:41
I tried to double check your above conclusion but come to disagree.
To my interpretation in your graph the red line (calibration) represents
DeltaFdown + deltaf_sat + deltaf_AFC + deltaf_bias
DeltaFup + deltaf_comp
In richardC10's nomenclature DeltaFup + deltaf_comp is:
DeltaFup + deltaf_comp = D1aircraft+D2aircraft + D2Satellite
D1aircraft+D2aircraft : error remaining after imperfect compensation (miscompensation)
D2Satellite ............ : Doppler component caused by sat's motion towards aircraft position
That means D1aircraft+D2aircraft and D2Satellite are of equal size but different sign at 22:41. For an assumed position of 15S 98E at 22:41 I calculate D2Satellite as 3.9 m/s or ~21Hz.
Then the miscompensation also was ~21Hz which leads me to a guestimate of 320+-100 kts for the southward component of the speed.
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Some "official" news
Blog - Cautious optimism in search for MH370
What is really new is that now you can have some answers from "them"! Very kind!
What is really new is that now you can have some answers from "them"! Very kind!
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Whilst we don't know how the 'investigation' looks at this today, we do know that we can't definitively say that ACARS was disabled (neutral term) before the last transmission.
We only know that ACARS did not make it's expected transmission at 17:37. This would place the time of disablement between 17:07 and 17:37.
There is some thought that the disabled transponder event should have triggered an ACARS message (can anyone confirm or refute this?). If this is true, then we would be further able to deduce that ACARS was disabled between 17:07-17:21. However, this would still not definitively place it before the 17:19 last transmission.
We only know that ACARS did not make it's expected transmission at 17:37. This would place the time of disablement between 17:07 and 17:37.
There is some thought that the disabled transponder event should have triggered an ACARS message (can anyone confirm or refute this?). If this is true, then we would be further able to deduce that ACARS was disabled between 17:07-17:21. However, this would still not definitively place it before the 17:19 last transmission.
Is that right ?
While being on the non civil side of aviation, I don't know all about ACARS. But from what I read, there supposed to be a ACARS over VHF also ? These logs we didnt se?
For the satcom/Inmarsat logs, it seems like ACARS did report stuff on a quite regulary basis, not more than 16 minutes between statusreports ?
While being on the non civil side of aviation, I don't know all about ACARS. But from what I read, there supposed to be a ACARS over VHF also ? These logs we didnt se?
For the satcom/Inmarsat logs, it seems like ACARS did report stuff on a quite regulary basis, not more than 16 minutes between statusreports ?
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The fact that both systems went dark separately offered strong evidence that the plane’s disappearance was deliberate.
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"Catastrophic" events usually don't take 14 minutes ....
Probably it is difficult to come up with a realistic failure scenario that would explain all the events how they unfolded in sequence. This is area strictly for experts in the aircraft systems.
By the way, this is old news, it is based on a March article, I think much more relevant to "human tampering" is the article quoted in #11270.
Probably it is difficult to come up with a realistic failure scenario that would explain all the events how they unfolded in sequence. This is area strictly for experts in the aircraft systems.
By the way, this is old news, it is based on a March article, I think much more relevant to "human tampering" is the article quoted in #11270.
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Originally Posted by Rev1.5
The fact that both systems went dark separately offered strong evidence that the plane’s disappearance was deliberate.
- There was an ACARS air to ground message at 1:07
- There was an RT transmission finishing about 1:19:30
- There were transponder responses up to 1:21:13
- There was no check in call (expected about 1:20)
- The next expected ACARS message ( around 1:23-1:37) was not recieved
- There was no response to a ground to air ACARS message at 2:03 and 2:05
- There was a satcom login by the aircraft at 2:25
- There was a ground to air phone call initiated and connected to the aircraft, but not answered at 2:39
- There than followed hourly short status message (1 packet each direction)
- at 7:13 there was another ground to air phone call initiated and connected to the aircraft, but not answered
- finally the remaining pings and the last logon
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Thank you all for these explanations.
Gysbreght: I don't understand yours:
"Therefore, if the difference between red and blue line is almost zero, the calibrated BFO is almost zero, and hence the north-south component of the airplane groundspeed is almost zero, i.e. the track is almost due east or west."
IMHO, no Doppler between a/c and sat happens when a/c and sat have parallel pathes and same speed, or concentric pathes and speeds proportional to the pathes radii.
Gysbreght: I don't understand yours:
"Therefore, if the difference between red and blue line is almost zero, the calibrated BFO is almost zero, and hence the north-south component of the airplane groundspeed is almost zero, i.e. the track is almost due east or west."
IMHO, no Doppler between a/c and sat happens when a/c and sat have parallel pathes and same speed, or concentric pathes and speeds proportional to the pathes radii.
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Whilst we don't know how the 'investigation' looks at this today, we do know that we can't definitively say that ACARS was disabled (neutral term) before the last transmission.
We only know that ACARS did not make it's expected transmission at 17:37. This would place the time of disablement between 17:07 and 17:37.
We only know that ACARS did not make it's expected transmission at 17:37. This would place the time of disablement between 17:07 and 17:37.
The early statements implied that it had logged off, meaning someone who knew how to find the ACARS menu had switched ACARS off.
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The Inmarsat document has a definition here
http://www.inmarsat.com/wp-content/u...pler-Study.pdf
http://www.inmarsat.com/wp-content/u...pler-Study.pdf
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Hi Gysbreght,
I tried to understand your equation from post #21. Unfortunately I failed.
But I can try to better explain my understanding :
I think up to the term DeltaFup + deltaf_comp we have a common understanding.
Of course it's kind of artificial to split DeltaFup into (D2aircraft + D2Satellite), yet I don't see any reasons not to do so. In contrary it's very helpful because the terminal applies deltaf_comp to compensate for D2aircraft only. The terminal doesn't know about D2Satellite because it supposes the sat to be stationary. Actually splitting into these two components is the natural thing to do, if you take the earth at rest as frame of reference.
With DeltaFup = (D2aircraft + D2Satellite) we can write:
DeltaFup + deltaf_comp = (D2aircraft + D2Satellite) + deltaf_comp = (D2aircraft + deltaf_comp) + D2Satellite
For a given aircraft position D2Satellite can be calculated from the angle between line of sight and sat velocity vector. The calculation is the same as for D3 aka DeltaFdown, only that instead of the coordinates of Perth the coordinates of the aircraft position are taken (and of course the L-Band Frequency).
Now deltaf_comp almost cancels out with D2aircraft, but just almost so, because the terminal's assumption of the sat position is not accurate (it supposes the sat position to be above the equator). That causes the terminal to calculate an inaccurate line of sight and thus an inaccurate line of sight speed.
(D2aircraft + deltaf_comp) is what I called "miscompensation" before. It depends on the offset of the sat from its geostationary position and on the aircraft velocity vector (mainly the component of the aircraft velocity that is parallel to the offset of the sat from its geostationary position i.e: its north/south component).
I tried to understand your equation from post #21. Unfortunately I failed.
But I can try to better explain my understanding :
I think up to the term DeltaFup + deltaf_comp we have a common understanding.
Of course it's kind of artificial to split DeltaFup into (D2aircraft + D2Satellite), yet I don't see any reasons not to do so. In contrary it's very helpful because the terminal applies deltaf_comp to compensate for D2aircraft only. The terminal doesn't know about D2Satellite because it supposes the sat to be stationary. Actually splitting into these two components is the natural thing to do, if you take the earth at rest as frame of reference.
With DeltaFup = (D2aircraft + D2Satellite) we can write:
DeltaFup + deltaf_comp = (D2aircraft + D2Satellite) + deltaf_comp = (D2aircraft + deltaf_comp) + D2Satellite
For a given aircraft position D2Satellite can be calculated from the angle between line of sight and sat velocity vector. The calculation is the same as for D3 aka DeltaFdown, only that instead of the coordinates of Perth the coordinates of the aircraft position are taken (and of course the L-Band Frequency).
Now deltaf_comp almost cancels out with D2aircraft, but just almost so, because the terminal's assumption of the sat position is not accurate (it supposes the sat position to be above the equator). That causes the terminal to calculate an inaccurate line of sight and thus an inaccurate line of sight speed.
(D2aircraft + deltaf_comp) is what I called "miscompensation" before. It depends on the offset of the sat from its geostationary position and on the aircraft velocity vector (mainly the component of the aircraft velocity that is parallel to the offset of the sat from its geostationary position i.e: its north/south component).
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Gysbrecht: sorry, we don't speak about the same value. My remark was about "pure" Doppler between a/c and sat. I had not read you with enough attention...
Ole-Ole: how do you find a "D2Satellite" Doppler (Doppler between sat and a fixed point where the a/c is in my understanding) of 43Hz at 22:41 between sat and a fixed point 15S 98E?
In my simple model, I have a 3.96 m/s LoS speed for these data. Which give (to me!) -21.7Hz (for 1643MHz).
Ole-Ole: how do you find a "D2Satellite" Doppler (Doppler between sat and a fixed point where the a/c is in my understanding) of 43Hz at 22:41 between sat and a fixed point 15S 98E?
In my simple model, I have a 3.96 m/s LoS speed for these data. Which give (to me!) -21.7Hz (for 1643MHz).
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Ian,
Unfortunately the ACARS logs are 'under wraps'. Aside from the fuel load on board at 17:07, the absence or presence of a log off is also vital data in regards to the sequential timeline. This is under the purview of the criminal investigation, which is still open and ongoing.
I tend to believe that those 'early' reports vis a vis ACARS retain credibility.
If ACARS was tidily switched off, we then are almost certainly faced with an hostile act, either by crew or interloper. This is not pleasant to contemplate, but contemplate we must.
Along these lines (and I am in no way casting blame), the redundant FL350 transmissions AND the failure to read back the Ho Chi Min frequency loom much larger as true outliers, IMO.
Unfortunately the ACARS logs are 'under wraps'. Aside from the fuel load on board at 17:07, the absence or presence of a log off is also vital data in regards to the sequential timeline. This is under the purview of the criminal investigation, which is still open and ongoing.
I tend to believe that those 'early' reports vis a vis ACARS retain credibility.
If ACARS was tidily switched off, we then are almost certainly faced with an hostile act, either by crew or interloper. This is not pleasant to contemplate, but contemplate we must.
Along these lines (and I am in no way casting blame), the redundant FL350 transmissions AND the failure to read back the Ho Chi Min frequency loom much larger as true outliers, IMO.
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Ole-Ole: how do you find a "D2Satellite" Doppler (Doppler between sat and a fixed point where the a/c is in my understanding) of 43Hz at 22:41 between sat and a fixed point 15S 98E?
In my simple model, I have a 3.96 m/s LoS speed for these data. Which give (to me!) -21.7Hz (for 1643MHz).
In my simple model, I have a 3.96 m/s LoS speed for these data. Which give (to me!) -21.7Hz (for 1643MHz).
Already fixed it. And the speed guestimate too : 36000/800 * 3.9 m/s ~= 160 m/s = 320 kts
36000 : Distance aircraft -> sat in km
800 : Sat offset from geostationary position in km
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Ulric
The Indonesians have stated that they didn't see it pass "over their territory." I have no reason to question that statement.
This also indicates to me that the person flying the plane wouldn't have wanted to enter their FIR unannounced.
Is that a constraint? I don't remember seeing any firm data either way?
This also indicates to me that the person flying the plane wouldn't have wanted to enter their FIR unannounced.