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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 15th Mar 2014, 09:38
  #3801 (permalink)  
 
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These new developments make the reports of pax mobile phones ringing much more plausible now.
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Old 15th Mar 2014, 09:39
  #3802 (permalink)  
 
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Press conference #MH370 scheduled at 5.30pm today is cancelled.

No reason given on twitter

Live TV | Astro Awani - have reporter reporting from there in an empty conference room but in Malay.
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Old 15th Mar 2014, 09:40
  #3803 (permalink)  
 
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Cargo Inventory

Some day we will get to hear what MAS believed was in the cargo manifest, it's perhaps too sensitive to release for now.
But given increased security/scanning over the years how easy is it still to load cargo described as "X" but actually contain "Y" ?
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Old 15th Mar 2014, 09:41
  #3804 (permalink)  
 
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Military defence systems

What does all this mean in terms of military defence systems throughtout SouthEast Asia and further.? It looks as if I can load up with nukes and ramble around the skies to my hearts content till I find a nice place on which to drop them. No one will 'see' me with either ground radar, airborne radar or satellite imagery. I thought billions were spent on magic protective envelopes that no missile or aircraft could penetrate. So much for all those campaign ribbons on the military chests not to mention presidential pride of inviolable airspace.
I can't believe that 'they' don't know plenty and that we are not being lead down every garden path there is in order to cover up the reality.
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Old 15th Mar 2014, 09:42
  #3805 (permalink)  
 
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In answer to Why would hijackers crash into the sea/go beyond fuel range you have to remember that these are desperate and highly motivated people to a degree which our idea of "logic" cannot comprehend.

Who says the hijackers crashed the plane into the ocean? One of the pilots might have done that when realising that all was lost. perhaps a pilot also repeatedly warned the hijackers that fuel was running out, but was ignored....this has happened before.
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Old 15th Mar 2014, 09:43
  #3806 (permalink)  
ekw
 
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A lot of people are jumping to conclusions with the word 'hijack'. It just means unauthorised excursion. The pilot flying is still in the frame. If it is murder suicide then where better to hide the evidence than in the deepest most uneven part of the Ocean. That would be SW of LKP.
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Old 15th Mar 2014, 09:47
  #3807 (permalink)  
 
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Originally Posted by B777FD View Post
These new developments make the reports of pax mobile phones ringing much more plausible now.
Indeed, the total lack of information about those investigations is very suspicious.

I can't help but think there is indeed a secret mission in progress to what is becoming more and more likely to be the final location.
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Old 15th Mar 2014, 09:47
  #3808 (permalink)  
 
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Thanks StormyNight 3965 for the post of satellite angle diagram.

The angle of altitude of satellite INMARSAT IOR (which is as I mentioned the only ACARS one covering this area) at 64 degrees East, as viewed from a place on Earth, which is what the lines show, can be calculated from the distance from observer (or pinger) to satellite.

This, in turn, can be calculated very precisely from the time taken to negotiate a single ping (which has some back and forwards messages).

So they have calculated such an angle of 40 degrees for the last ping.
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Old 15th Mar 2014, 09:50
  #3809 (permalink)  
 
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Just an observation about the Prime Minister's statement after reading it twice.

The idiomatic structure suggests it was drafted or edited by a native English-speaker, and is not a translation of a Malaysian language original. And the idiom reads a bit more American, than British.

Given some of the phrasing, and the precise choice of words, very likely that NTSB and/or AAIB personnel in Malaysia (or elsewhere) were involved in writing the statement.
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Old 15th Mar 2014, 09:58
  #3810 (permalink)  
 
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Originally Posted by The_Loner View Post
Has anyone besides me noticed the conspicuous absence of information related to getting a fix on the sonar beacons on the CVR and DFDR?

There are enough navies in those waters watching each other and using sophisticated technology to listen for trespassers that someone must have heard something.

Recent hints about a seismic event in the South China Sea are probably veiled hints as to where the 777 may have splashed. And if no one heard anything, then the governments don't want the other governments to know how really bad their surveillance nets are.

For all of that, we may have to wait 20 years for the wreckage to be accidentally found by oil prospectors... It is an ugly story of jihadis getting in over their heads (and losing control of the plane) and Maylaysia not wanting to admit that they failed to prevent it.
The sonar locators on the CVR and DFDR are extremely short range looks like the beancounters were involved again. They are fine if you have a known position down to half a mile or so in water, but their range is only a kilometer or so at best. One would have thought with whale 'song' being heard over hundreds of kilometers that engineers could have made these locators more powerful, but it possibly saved $100 per airframe to have pen torch sized locators with only 30 days power.
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Old 15th Mar 2014, 10:01
  #3811 (permalink)  
 
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>So they have calculated such an angle of 40 degrees for the last ping.

Not being an RF engineer I'd like to know what sort of error margin they have on that reading. My gut feel is that once you start taking into account a possibly damaged antenna and damaged transmitter (lower voltage maybe) the time to get a response might be a little longer. When the talk was around GPS packets in the ping and triangulation it seemed more solid.

I'm having a hard time seeing the satellite reading as the smoking gun that the media and SAR teams are making it out to be. Unless there is another source we aren't being told about.
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Old 15th Mar 2014, 10:03
  #3812 (permalink)  
 
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StormyKnight
Would the 40 degrees be determined by received signal strength as suggested?
That's an interesting picture but I'm not sure the signal strength method is the only method available for "triangulation" in this case. I'll outline some general methods that are used in various systems, commenting also on TelcoAG's posts at 07:39 and 09:02 UTC today:

1. The signal strength method is a possibility but I believe its accuracy may be rather poor.

2. Another possible method is to measure the signal timing differences from two satellites, if data from both are available ( "reversed GPS principle" as someone said).

3. A third method may be to utilize the "Time Alignment" procedure that is widely used in e.g. GSM. Here, the system makes a signal timing adjustment to align the arrival time of radio packets from each active transmitter so that they align with the time slots in the receiver's (the satellite) TDMA (time division multiplex) channel frame. This adjustment value is an indication of the transmitter-receiver distance and can be used to plot a circle where the transmitter is located. Use 2 satellites and you get two cross bearings, one north and one south.
The caveat with this method, hovever, is that it is normally used only when you actually establish a connection to send a payload. For a periodic "ping" you normally don't need to allocate a timeslot.

4. It is quite conceivable that the Inmarsat satellite can measure the "elevation angle" of the received signal directly. Newer satellites have narrow individual "spot beams" to increase capacity, and obviously the system can keep track of which beam is allocated to any particular transmission.

5. Finally, the "ping time" itself (i.e. the roundtrip delay), if measured with enough precision, tells the distance between transmitter and receiver and can conceivably be used to plot a range circle as with the time alignment method.

Last edited by snowfalcon2; 15th Mar 2014 at 10:10. Reason: Added method 5
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Old 15th Mar 2014, 10:10
  #3813 (permalink)  
 
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A lot of weight is indeed being put on the sat pings. I hope the engineers have thoroughly checked for latency issues or time stamp errors to ensure everything is as it seems. There are a lot of protocol levels in that system.
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Old 15th Mar 2014, 10:16
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Have just heard the Malaysian PM's statement on SKY, he indicated that the SSR transponder was switched off and Malaysian Air Defence primary radar data indicated a track change in a westerly direction, flying back over the Malaysian peninsula. If this is true, as its an Air Defence system, why were air defence assets not launched to intercept the contact?
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Old 15th Mar 2014, 10:18
  #3815 (permalink)  
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Stormy,

You can see also from this chart that the 40 degree arc highlighted passes thru the southern tip of Veitnam. But they are negating that area now on their Military primary plots data ( which maybe erroneous). I'm sorry but I think they should keep concentrating on the South Veitnam coastline. The New Zealand oil rig worker is still not backing down from his observations.
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Old 15th Mar 2014, 10:21
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With respect to ultimate flight path, one can create possible corridors after subtracting out the effective ranges of military radars of various governments in the region, and depending on whatever judgments one cares to make about how alert the operators were.

And sitting due south of the Maldives is Diego Garcia, possibly having the most powerful radars in the whole region, with a 360 field of view, whose operators are unlikely to be sleeping.
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Old 15th Mar 2014, 10:23
  #3817 (permalink)  
 
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There is only one INMARSAT covering ACARS coms over the Indian Ocean. It is IOR located at 64 degrees East, 35890km above the equator, as shown in the Malaysian diagram.

So angle (or equivalently distance) calculations must be being done by using just the one satellite.

I think their diagram shows that they have a very accurate method of calculating that distance. I understand that this can be done via ping latency but there may be other methods.

The distance from the satellite so calculated has given them the 40 degrees altitude as shown. I calculate that this equates to 4840km distance at sea-level around the earth from the point directly below the satellite.
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Old 15th Mar 2014, 10:25
  #3818 (permalink)  
 
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Originally Posted by Sheep Guts View Post
Stormy,

You can see also from this chart that the 40 degree arc highlighted passes thru the southern tip of Veitnam. But they are negating that area now on their Military primary plots data ( which maybe erroneous). I'm sorry but I think they should keep concentrating on the South Veitnam coastline. The New Zealand oil rig worker is still not backing down from his observations.
Somewhere on the 40 degree arc was the last sat communication at 8:11am local time (daylight - sunrise was 7:22am in Kuala Lumpur Sunrise and Sunset for Malaysia ? Kuala Lumpur ? March 2014)

Vietnam is further East so the sun would have been up even earlier.
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Old 15th Mar 2014, 10:25
  #3819 (permalink)  
 
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Although it often looks like it, this is NOT the Daily Mail discussion forum, but a PROFESSIONAL FLIGHT CREW forum.

Please refrain from commenting if not flightcrew or other aviation professional.
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Old 15th Mar 2014, 10:28
  #3820 (permalink)  
 
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Although it often looks like it, this is NOT the Daily Mail discussion forum, but a PROFESSIONAL FLIGHT CREW forum.

Please refrain from commenting if not flightcrew or other aviation professional.
Absolutely agree iro technical stuff about the aircraft etc. Given scope of this story there's plenty of room for all sorts of other comment whether about history, politics and linguistics or tech background in satellites and radio.
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