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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 25th Mar 2014, 11:14
  #7981 (permalink)  
 
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I think that this now shows that the idea of just the onboard black boxes must change...Airfrance and now this crash must push for an external radio recording device to be retro fitted to all transport planes a.s.a.p.
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Old 25th Mar 2014, 11:22
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Press release

The Minister of Transport just said that a detailed Press release will be given just after the PC, with some detailed data from AAIB.
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Old 25th Mar 2014, 11:37
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Could this secondary flight plan have been activated easily with a few keystrokes?
The PPRuNe search function suggests "secondary flight plan" has been discussed 663 times already on this very thread....
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Old 25th Mar 2014, 11:40
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Could a black box not be fitted with a GPS tracker?
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Old 25th Mar 2014, 11:47
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I think that this now shows that the idea of just the onboard black boxes must change...Airfrance and now this crash must push for an external radio recording device to be retro fitted to all transport planes a.s.a.p.
Agreed.

When recorders were developed, all you could do was record the data onto a local device, make the device as indestructible as possible, and hope it could be found in the event of a crash.

In 2014, that seems almost quaint.

It's like backing up important files on your laptop to a separate folder on the same laptop. Pretty much useless if your laptop gets stolen.

I do understand pilots concerns about privacy. But the reality is that most people do have to be a bit discreet about conversations they have in their workplace.

Perhaps the solution is to have the data stored at a central location (e.g. NTSB), only to be accessed as part of a formal investigation, and not routinely available to company management.
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Old 25th Mar 2014, 11:47
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Ocean current

I'm looking at various sites to have an idea about maritime current in the region 43.976S/90.96E (Chinese debris picture: -43° 58' 34.0 90° 57' 37.0 ) to try estimating the approximative position of the aircraft at impact on the sea.
The average current is 0.2m/s in this area and with a South Eastern direction. It gives roughly 0.72 km/h,that is a 17.3 km per 24 hours. The aircraft disappeared in the ocean on the 8th of March, 8 days before the picture, it would make a SE 140km drift.
It can be applied the same drift for the French debris although we only that it is 550 km in the North.
Of course this a pure speculation and we still do not know yet if these debris are from Flight 370.
Unfortunately the weather is not good at this time and searches are halted.



Sources : oceanmotion.org and oceanweather.com
It is interesting also to look at Skyvector and add the "barbs" to the Weather layer.

Last edited by Squawk_ident; 25th Mar 2014 at 12:37. Reason: Sout Eastern i/o South Western...
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Old 25th Mar 2014, 11:51
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Originally Posted by buttmonkey1
before holding up the portable elt's to the windows, lol, you better remember
to all stand around pissing on it cause its probably a rescu406 which battery is activated by salt water.
isn't that for the two flotation devices, elt are meant for crash on ground use so no need to take a leak
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Old 25th Mar 2014, 11:57
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I think the idea of EPIRBs is not the best way forward. I would think more about using the satellite broadband link. Audio feed parallel with a CVR channel, 48 kb codec (G722 or similar would give enough audio bandwidth to ID warning tones) add a 2kb slow data channel for an integrated GPS data. Add error correction and you could fit 2 into the minimum broadband link.
Activation could be for example an aircraft loses ADS-B, VHF comms, departs flight plan, departs cleared altitude etc then ATC could poll the aircraft and switch on the CVR link.
Automatic battery back up incase of power failure.

The issue will be with how those in the cockpit feel about possible remote monitoring of anything they say?
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Old 25th Mar 2014, 12:00
  #7989 (permalink)  
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Information provided to mh370 investigation by uk air accidents investigation branch

Information provided to mh370 investigation by uk air accidents investigation branch (aaib)

25/03/14

on 13 march we received information from uk satellite company inmarsat indicating that routine automatic communications between one of its satellites and the aircraft could be used to determine several possible flight paths.

Inmarsat uk has continued to refine this analysis and yesterday the aaib presented its most recent findings, which indicate that the aircraft flew along the southern corridor.

As you have heard, an aircraft is able to communicate with ground stations via satellite.

If the ground station has not heard from an aircraft for an hour it will transmit a 'log on / log off' message, sometimes referred to as a ‘ping’, using the aircraft’s unique identifier. If the aircraft receives its unique identifier it returns a short message indicating that it is still logged on. This process has been described as a “handshake” and takes place automatically.

From the ground station log it was established that after acars stopped sending messages, 6 complete handshakes took place.

The position of the satellite is known, and the time that it takes the signal to be sent and received, via the satellite, to the ground station can be used to establish the range of the aircraft from the satellite. This information was used to generate arcs of possible positions from which the northern and southern corridors were established.

Refined analysis from inmarsat
in recent days inmarsat developed a second innovative technique which considers the velocity of the aircraft relative to the satellite. Depending on this relative movement, the frequency received and transmitted will differ from its normal value, in much the same way that the sound of a passing car changes as it approaches and passes by. This is called the doppler effect. The inmarsat technique analyses the difference between the frequency that the ground station expects to receive and that actually measured. This difference is the result of the doppler effect and is known as the burst frequency offset.

The burst frequency offset changes depending on the location of the aircraft on an arc of possible positions, its direction of travel, and its speed. In order to establish confidence in its theory, inmarsat checked its predictions using information obtained from six other b777 aircraft flying on the same day in various directions. There was good agreement.

While on the ground at kuala lumpur airport, and during the early stage of the flight, mh370 transmitted several messages. At this stage the location of the aircraft and the satellite were known, so it was possible to calculate system characteristics for the aircraft, satellite, and ground station.

During the flight the ground station logged the transmitted and received pulse frequencies at each handshake. Knowing the system characteristics and position of the satellite it was possible, considering aircraft performance, to determine where on each arc the calculated burst frequency offset fit best.

The analysis showed poor correlation with the northern corridor, but good correlation with the southern corridor, and depending on the ground speed of the aircraft it was then possible to estimate positions at 0011 utc, at which the last complete handshake took place. I must emphasise that this is not the final position of the aircraft.

There is evidence of a partial handshake between the aircraft and ground station at 0019 utc. At this time this transmission is not understood and is subject to further ongoing work.

No response was received from the aircraft at 0115 utc, when the ground earth station sent the next log on / log off message. This indicates that the aircraft was no longer logged on to the network.

Therefore, some time between 0011 utc and 0115 utc the aircraft was no longer able to communicate with the ground station. This is consistent with the maximum endurance of the aircraft.

This analysis by inmarsat forms the basis for further study to attempt to determine the final position of the aircraft. Accordingly, the malaysian investigation has set up an international working group, comprising agencies with expertise in satellite communications and aircraft performance, to take this work forward.

In annex i (attached) there are three diagrams, showing:

Doppler correction contributions

this diagram shows the doppler contributions to the burst frequency offset.


Mh370 measured data against predicted tracks

the blue line is the burst frequency offset measured at the ground station for mh370.

The green line is the predicted burst frequency offset for the southern route, which over the last 6 handshakes show close correlation with the measured values for mh370.

The red line is the predicted burst frequency offset for the southern route, which over the last 6 handshakes does not correlate with the measured values for mh370.


Example southern tracks

this shows the southern tracks for a ground speed of 400 and 450 knots ground speed. It should be noted that further work is required to determine the aircraft speed and final position.


Source: https://www.facebook.com/permalink.p...78566888854999

Last edited by A69; 25th Mar 2014 at 12:44. Reason: Added Images and Source link
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Old 25th Mar 2014, 12:04
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oldoberon
MAS no satellite contract...
Has that been positively established? I remember this a one of the statements to be debunked afterwards. For example this "source" says:

“It is Mas procedure to switch ACARS, VHF, and High Frequency selection off but this is only for flights to China as the service provider for Mas does not cover China. Some if not all pilots switch them all off for a while and then later switch SATCOMM back on to force the system into SATCOMM mode.”
MISSING MH370: ACARS cannot be disabled - Latest - New Straits Times
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Old 25th Mar 2014, 12:13
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Quote:
@syseng68k
It's actually much easier to recover data from over-written digital media. FBI software can recover data from digital media that has been over-written multiple times, or reformatted repeatedly.
Absolutely false. As mentioned before, it is simply impossible to recover any physically overwritten digital information.
While there is a theory that this is possible, nobody has been able to demonstrate being able to recover significant amounts of data.
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Old 25th Mar 2014, 12:16
  #7992 (permalink)  
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Originally Posted by sky9
I see that Inmarsat have used a speed of 450 kts for their calculation. Assuming that a 777 operates at 0.84 or there abouts that equates to a TAS closer to 500kts.

How would that affect the arcs that they have published and how far down those arcs the aircraft might have flown.
What is the T7 range speed? It would not be 'thereabouts'; it is either 0.84 or it isn't.

The speed of 450 kts groundspeed predicates a constant wind iro 60 kts head wind assuming an OAT of -40C and my memory and calculation being correct which give a TAS of 510.
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Old 25th Mar 2014, 12:27
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@A69 could you please provide us with the official source/weblink of the "AAIB summary" ?
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Old 25th Mar 2014, 12:28
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Regarding the yellow and the red track on the aaib image/globe.

- Yellow represents the solution which covers the greatest distance, red the solution for smallest distance?
- Yellow is great circle, red is constant magnetic heading?

Together with the search areas that points to great circle solution, i.e. FMC and not to A/P => deliberate action?

Edit: Thinking about it, there could be a solution with 450 knots and constant magnetic heading which is much closer to the yellow track => deliberate action not confirmed
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Old 25th Mar 2014, 12:36
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I think the idea of EPIRBs is not the best way forward. I would think more about using the satellite broadband link. Audio feed parallel with a CVR channel, 48 kb codec (G722 or similar would give enough audio bandwidth to ID warning tones) add a 2kb slow data channel for an integrated GPS data. Add error correction and you could fit 2 into the minimum broadband link.
Activation could be for example an aircraft loses ADS-B, VHF comms, departs flight plan, departs cleared altitude etc then ATC could poll the aircraft and switch on the CVR link.
Automatic battery back up incase of power failure.

The issue will be with how those in the cockpit feel about possible remote monitoring of anything they say?
ionagh; with respect (and I mean that) your proposal is not proof against tampering or catastrophic failure of the a/c

A fiber optic cable run from the AIMS unit to a internal hull mounted data exchange/charging/monitoring device constantly updating the external EPIRB/data recorder would provide a truly independent resource for SAR/AAIB people. No CVR snooping either.

It wouldn't need ED-12 certification as total failure would not affect the a/c

(yes, I did look it up)

ED-12B
Software Considerations in Airborne Systems and Equipment Certification
Latest Revision December 1, 1992
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Old 25th Mar 2014, 12:39
  #7996 (permalink)  
 
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Together with the search areas that points to great circle solution, i.e. FMC and not to A/P => deliberate action?
Ole ole, looks like it.

It also looks like the green track on the graphic I put together, the western route using a constant magnetic hdg, as suspected, does not match any track which would correlate with the hourly satellite pings.
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Old 25th Mar 2014, 12:43
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Originally Posted by APLFLIGHT
@A69 could you please provide us with the official source/weblink of the "AAIB summary" ?
Yes, It's on the facebook page of Ministry of Transport Malaysia.
Here's the link https://www.facebook.com/permalink.p...78566888854999
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Old 25th Mar 2014, 12:47
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In the doppler shift diagram there are three bursts close to where MH370 turned south between ~ 18:20 -18:30 utc. If that is not just symbolic, it would indicate turning south happened in that time window.

- Why three burst in such a short time?
- And wasn't last PSR contact at 18:40 utc (2:40 MYT)?
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Old 25th Mar 2014, 12:52
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Question Inmarsat Pings

BBC are reporting a final partial Inmarsat handshake ping received at 08:19 following the routine handshake received at 08:11 with no explanation. I'm not familiar with 777 systems, but could this have resulted from a transient power interruption during bus transfer following the loss of a genny?
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Old 25th Mar 2014, 12:56
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Small objects, and objects that that are floating "high", will be subject to surface drift, the wind and wave derived motion of the uppermost layer of sea water, which is typically in the direction of the surface wind and should be applied after allowance is made for the current. In an areas such as the one under consideration, the surface drift can be quite fast.
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