Malaysian Airlines MH370 contact lost

[MG23]

Originally Posted by OleOle

- why no more Ground Initiated to Air Telephony Calls ?

I haven't looked at the precise times, but I would presume either the airline or ATC called when they disappeared and couldn't be contacted by radio, then called again when they were overdue at their destination. Not much point calling every ten minutes if no-one is responding.

[Rev1.5]

23:13 - Ground Initiated to Air Telephony Call - Zero Duration (Not Answered)

Somewhere there will be a record of who made that call.
Has that information been made public?

[rampstriker]

It's infuriating how coy the Malaysians are being about the plane's PSR altitude profile after the transponder datastream stopped. This information is so critical to understanding what may have happened.

[threemiles]

18:25 - Log-On Request, initiated from the aircraft terminal. This is the end of the link lost period that began at sometime between 17:07:48 and 18:03:41.

This is quite exactly 1 hour after the last SSR response.
I bet this is not coincidence and there is some technical explanation behind it.

Also: the 00:19 Log-on request was explained as a system restart after flame-out and subsequent RAT or battery kicks in or whatsoever. How then is the 18:25 Log-on request explained? There would have been no flame-out before that time. Generators failed? APU not started? Low altitude? There must be a technical reason for that, too.

[Ian W]

Originally Posted by Propduffer

The Vietnamese have indicated that they saw the plane turn around but they didn't give any details as to whether this occurred before or after the transponder was turned off, but if we assume that it occurred after the transponder was turned off we will know that Vietnamese primary radar tracked the flight as early as 1:22 local time. The Thai government has stated that they first picked up the flight at 1:28 'flying in the direction opposite from the MH370 plane, 'back toward Kuala Lumpur' (paraphrased.) The Malaysians have remained vague and the Indonesians have left it up to the reader to read between the lines to know that they tracked the flight at all. (see my post above)

It is probably this report from Ho Chi Minh that they had seen the aircraft turn back (presumably on PSR) that was why the Malaysians took on the RCC role rather than the Vietnamese who were meant to be the control authority, or the Singaporians whose airspace the loss of contact occurred in. It is another reason that the loss of contact appears too well timed to be coincidental with an in flight emergency. The subsequent track and profile of the aircraft was also not what one would expect from an aircraft with a severe emergency. This is no doubt why the Malaysians seem to think this was a criminal act.

[TOMCAT22]

Quote:
23:13 - Ground Initiated to Air Telephony Call - Zero Duration (Not Answered)
Somewhere there will be a record of who made that call.
Has that information been made public?


I have followed this thread from the very beginning and I believe this call was made by someone from Malaysia airlines. I can't find the exact reference but I remember reading it in a transcript that someone (perhaps maintenance personnel) called the plane when the controllers couldn't see it on radar.

[MrPeabody]

Threemiles,

The 18:25 logon was initiated by the aircraft, if you refer to the Inmarsat BFO graph it mentions possible turn. Had a tight turn been initiated that shadowed the SATCOM beam, this would have been when the aircraft reacquired the satellite (bank reduced to the point of reacquisition).

Cheers

[oldoberon]

Looking at the relative positon of the aircraft and satellite I don't think a left turn wound have screened the aerial but a right hand would, remember the chinese video to the pax, that had a right hand turn??

[threemiles]

I don't think a turn causes a logon. This would generate endless logons when airplanes fly holdings or so.
To me a logon would happen after some kind of system restart. As if you boot your windows computer.
I do not see a difference in the sequences at 18:25 and 00:19, that makes it strange when the latter was very firmly associated to a power up.
I would believe that this system behaviour is essential to the investigation and it should be replayed on board a real life flight. My feeling is that there is more involved than just a manual intervention by someone onboard.

[hamster3null]

Originally Posted by Rev1.5

Somewhere there will be a record of who made that call.
Has that information been made public?

In all likelihood, someone at Malaysian Airlines trying to figure out where the plane is. This is 45 minutes after its scheduled arrival in Beijing.

[hamster3null]

Originally Posted by Shadoko

"Raw data PDF": 18:25 - Log-on Request, initiated from the aircraft terminal. This is the end of the link lost period that began at sometimes between 17:07:48 and 18:03:41.

What it the meaning of that?
- a trick (before turning South) from somebody who handled the a/c knowing it had have to be "viewed" on a west route?
- an automatic sat link after HF was available along the route above Malaysia and lost again?
- some automatic data Tx from a so big change in flight caracteristics it had to be "signaled" for frequency or BFO adjustment between sat and a/c?
- ... ?

It would be interesting to know what were the subsequent "user data".

If the system was not responding to interrogations at 18:03 and it initiated a logon at 18:25, the logical conclusion is that it was physically shut down from the cockpit at some point prior to 18:03 and then (possibly unintentionally) turned back on at 18:25.

The interesting question is what would have caused it to come back on. Perhaps the aircraft was flown manually between 17:21 and 18:25 and the pilot turned on the autopilot to continue the route via waypoints at 18:25.

"User data" may be part of the standard logon procedure for this aircraft, you see the same two packets at 16:01:16.

Side note: It looks like attempts to call the aircraft at 18:39 and at 23:13 had the side effect of resetting the interrogation timer, which is why we see handshakes at 19:40 and 00:11.

[kayej1188]

Why would a turn initiate a log-on? What are some possible causes of the loss of connection from sometimes after 17:07 until 18:25? Lastly, no doubt that at least one of the pax would have made a cell phone call/text when the plane dropped to 5000 ft. This must mean all the passengers were out of commission at that time, no?

[SAMPUBLIUS]

CELLPHONE OR WHATEVER CALLS

Lastly, no doubt that at least one of the pax would have made a cell phone call/text when the plane dropped to 5000 ft. This must mean all the passengers were out of commission at that time, no?

At night - how many passengers at that time would or could know what the altitude or direction was- absent a violent manuver ?

Puuuhleese do not read too much into such events

Its fairly certain the plane is in the Indian Ocean - and until found, and passenger or flight recorder data are found and analyzed- ALL else is just fodder for the next ' tell all speculation book "

[MrPeabody]

hamster3null,


The SATCOM is powered by Left Main AC and comes on with power established.


The system will reacquire if the aircraft to satellite beam is interrupted or power interrupted. Beam interruption could be due to wing masking (large bank angle), blind spots or terrain. This aircraft is the last of the Malaysian aircraft to be fitted with dual side mounted antenna; this in itself raises some food for thought.


Side mounted systems have fore and aft blind spots (key holes). The satellite connection was lost somewhere between 17:07 and 18:03; apparently the period where some severe altitude changes were to have taken place. The course from around 18:03 to 18:22 is straight and toward the satellite; if climbing in this period, could it simply be the SATCOM is in a drop out condition?? Change direction at 18:25 and system reacquires.


Alternatively Left AC was turned off and re-established at 18:25.


My guess is a drop out condition.

[hamster3null]

Originally Posted by MrPeabody

hamster3null,


The SATCOM is powered by Left Main AC and comes on with power established.


The system will reacquire if the aircraft to satellite beam is interrupted or power interrupted. Beam interruption could be due to wing masking (large bank angle), blind spots or terrain. This aircraft is the last of the Malaysian aircraft to be fitted with dual side mounted antenna; this in itself raises some food for thought.


Side mounted systems have fore and aft blind spots (key holes). The satellite connection was lost somewhere between 17:07 and 18:03; apparently the period where some severe altitude changes were to have taken place. The course from around 18:03 to 18:22 is straight and toward the satellite; if climbing in this period, could it simply be the SATCOM is in a drop out condition?? Change direction at 18:25 and system reacquires.


Alternatively Left AC was turned off and re-established at 18:25.


My guess is a drop out condition.

The course from 18:03 to 18:22 is not exactly toward the satellite. The aircraft was going at heading 285..295 and the satellite was at the heading 262..265 and high in the sky. I just don't see a drop out condition that would result in SATCOM operation being continuously disrupted for 22+ minutes. That's why I speculate about the system being manually powered down.

Left AC being off is an interesting possibility. What other systems are there on the same circuit?

[Propduffer]

When I said that other people had brought up the subject I made a misassumption that what I was referring to was common knowledge.

It comes from a blowup of the graphic given to the families.

If you have very good eyes or if you blow up the picture; it shows a constant track for each sweep of the search radar for the a/c along the upper green airway.

The MH370 track does not present as being so symmetrical.
This picture was released by the Malaysians.

I think the person who believed it hand flown made a good case. I see other supporting evidence. The known altitude excursion after turnaround also required hand flying.

I see much evidence to support the hand flown premise.

[DrPhillipa]

Anyone have an idea what these large amounts of User Data are in the logs if they are not ACARS? (T-Channel RX)

Also would one emergency land a T7 in the dark at Penang without comms from the South West or from the North East?

4.1.1.2.1 P channel. Packet mode time division multiplex(TDM) channel transmitted continuously from the aeronautical ground earth station (GES) in the to-aircraft direction to carry signalling and user data. A P channel being used for system management functions is designated Psmc, while a P channel being used for other functions is designated by Pd. The functional designations Psmc and Pd do not necessarily apply to separate physical channels.

4.1.1.2.2 R channel. Random access (slotted Aloha) channel, used in the from-aircraft direction to carry signalling and user data. An R channel being used for system manage-ment functions is designated Rsmc, while an R channel being used for other functions is designated Rd. The functional designations Rsmc and Rd do not necessarily apply to separate physical channels.

4.1.1.2.3 T channel. Reservation time division multiple access (TDMA) channel, used in the from-aircraft direction only. The receiving GES reserves time slots for transmissions requested by aircraft earth stations (AESs) according to message length. The sending AES transmits the message in the reserved time slots according to priority.

4.1.1.2.4 C channel. Circuit-mode single channel per carrier (SCPC) channel, used in both to-aircraft and from-aircraft directions. This channel is time division multiplexed to provide a primary channel for voice or data traffic and a sub-band channel for signalling, supervision and data messages. The use of the channel is controlled by assignment and release signalling at the start and end of each transaction.

The 4 channel designations in the SATCOM log, FYI.

[OleOle]

Text filtering of the A/C -> Ground down link comms

Time stamps are for T-Channel assignments.
Number of subsequent signaling units corresponds to amount of data send by A/C?

Downlink Comms:

16:00:23.905 5 Subsequent Signalling Units

16:01:20.405 5 Subsequent Signalling Units

16:09:37.905 8 Subsequent Signalling Units

16:11:04.405 5 Subsequent Signalling Units

16:28:01.905 10 Subsequent Signalling Units

16:29:17.905 30 Subsequent Signalling Units
16:29:42.405 13 Subsequent Signalling Units

16:41:53.405 6 Subsequent Signalling Units
16:41:58.405 12 Subsequent Signalling Units
16:42:17.905 30 Subsequent Signalling Units
16:42:33.405 30 Subsequent Signalling Units
16:42:48.905 29 Subsequent Signalling Units

16:55:24.405 30 Subsequent Signalling Units
16:55:38.905 30 Subsequent Signalling Units
16:55:53.905 30 Subsequent Signalling Units
16:56:08.905 5 Subsequent Signalling Units

17:06:49.906 30 Subsequent Signalling Units
17:07:04.905 30 Subsequent Signalling Units
17:07:19.905 30 Subsequent Signalling Units
17:07:34.905 30 Subsequent Signalling Units

18:28:06.407 5 Subsequent Signalling Units

@DrPhillipa

16:29 could be "Gate Out"
16:41 could be "Wheels Off"
OOOI Data - ASPMHelp

17:07 was an ACARS message Inmarsat used for calibration:

The engineers at Inmarsat were able to validate their estimates of the plane’s location by matching its position at 1:07 a.m., when it sent a burst of data through its Aircraft Communications and Reporting System, McLaughlin said.

Hunt for Jet Switches to Visual Search as Radar Empty - Bloomberg

[Ian W]

Originally Posted by kayej1188

Why would a turn initiate a log-on? What are some possible causes of the loss of connection from sometimes after 17:07 until 18:25? Lastly, no doubt that at least one of the pax would have made a cell phone call/text when the plane dropped to 5000 ft. This must mean all the passengers were out of commission at that time, no?

The number of phones left on 'inadvertently' in an aircraft is probably in the 5% range. So there could have been up to 10 cell phones active in MH370, they do not need anyone to tell them to connect as soon as they see a signal they do so. If they didn't it says nothing about the state of the pax.

[Propduffer]

Originally Posted by Pontis Navigator

My interpretation is that the track plot to the south east of the circle is MH370 at a medium altitude. The circle shows where the plot went dark, most likely as the aircraft dropped below the radar horizon. The continuation plot to the north west was regained as the aircraft resumed a climb.

I don't know what the circle represents, but we can see the 'MH370' track before and after the circle on a (gustimated) 295 degree heading. So the circle isn't where the track was lost. If you look closely at the MH370 track you'll see a series of dots that presumably indicate the sweeps of a search radar.

Using the circle for reference, look inside the circle and you will see two solid lines which I take to indicate airways. On the upper of these two airways there can be seen a series of dots which I also take to be representations of radar sweeps. These dots paint a much more symmetrical pattern than does the 'MH370 track.

I will add that these radar tracks provide no altitude information.
And I agree that this is a doctored composite.

Originally Posted by Pontis Navigator

Now I am not in to conspiracy theory, evasive routing etc, but that loss of contact could also have put the aircraft in the dark to Indonesian radar as well. Having gone out of cover why climb while within range of the PSR? One possibility is that going dark would throw off short range interceptors reliant on close radar control.

I do see strong evidence for evasive routing:
There are multiple indications that the flight descended sharply and passed over the Malaysian landmass at lower altitude than cruise. (Radar reports from the Malaysians and sightings of a plane descending on a westerly course near Kota Bharu, 'intermittant' Thai radar contact.) I believe that a blind spot in the Thai radar at Hat Yai was exploited to reduce exposure to Thai radar (this is borne out by Thai statements that their track was "intermittent" which it would not have been the case if the flight was at cruise altitude.)

I believe that subterfuge was used to decieve the Indonesian's monitoring their ATC and primary radar - from an Aceh view, the flight would have appeared along a frequently used airway which is used by flights from Penang to Australia. These airways avoid Indonesian national waters (beyond 12 miles.)

It's quite a coincidence that the flight flew a part that would mimic a skilled military spyflight's intended course to avoid detection from IGARI to the Indian ocean. Too big a coincidence for me to ignore.