Malaysian Airlines MH370 contact lost
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The speed of sound is not constant in water. It varies greatly with pressure, temperature, and salinity. One must also consider that the medium itself is moving, and at the bottom of the ocean the currents can be quite swift and unpredictable.
As a pressure wave (longitudinal?) changes in speed of propagation are interpreted by a microphone as a change of frequency, even if the source and target are stationary relative to each other.
As a pressure wave (longitudinal?) changes in speed of propagation are interpreted by a microphone as a change of frequency, even if the source and target are stationary relative to each other.
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Niner Lima
I can see a situation where one engine sucked air first, then the autopilot tried to maintain heading or track and altitude or speed, which resulted in a large yaw with roll angle followed by a spiral into the water.
ICAO has just announced a two-day meeting in May, covering several topics mentioned here, such as new guidelines on ULBs and deployable flight recorders:
MH370 Tragedy: ICOA to meet on global tracking - Latest - New Straits Times
"The unprecedented and unusual circumstances of flight MH 370 have been particularly difficult for civil aviation officials to resolve and the lack of definitive answers has been much harder still for the victims' families to come to terms with. They, above all, will benefit from a fuller explanation of this accident," he added.
Aliu also said ICAO recently added a new guideline on underwater locator beacon (ULBs) which will take effect in 2018.
ICAO’s Flight Recorder Panel is reviewing new methods to speed up process of determining accident sites, deployable flight recorders and the triggered transmission of flight data.
Furthermore reviews will be conducted on aviation security, travel documents as well as requirement for the transport of lithium batteries.
Aliu also said ICAO recently added a new guideline on underwater locator beacon (ULBs) which will take effect in 2018.
ICAO’s Flight Recorder Panel is reviewing new methods to speed up process of determining accident sites, deployable flight recorders and the triggered transmission of flight data.
Furthermore reviews will be conducted on aviation security, travel documents as well as requirement for the transport of lithium batteries.
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Originally Posted by selfin
FASID CNS/4A states both Banda Aceh and Lhokseumawe/Malikussaleh's PSR ranges are 90 NM. Apparently 60 NM might be closer to the truth.
Originally Posted by selfin
MH370 was below Butterworth's RADAR horizon for a significant period enroute VAMPI.
Originally Posted by hamster3null
if last known radar contact is near NILAM and MH370 wasn't visible to Indonesian radars at that point, it's pretty straightforward to get from NILAM to 20.8S 104.1E in less than 2000 NM without getting any closer. If radar slide is false though, MAPSO-IGREX-TOPIN-IKASA-Ocean Shield is 2213 NM (370 kts) while giving a wide berth to Indonesian airspace.
The unknown here is what the Indonesian radar capabilities actually are, or what they were perceived to be at any rate, they have a 10,000 ft mountain about 30 miles south of Malikussaleh and it would seem logical for them to have placed their military radar antenna somewhere on that height.
Last edited by Propduffer; 8th Apr 2014 at 19:53.
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777-2 fuel exhaustion simulator test
This post was just magically undeleted.
As a 777 pilot I, like many others, have wondered how the 777 would perform in the scenario where the pilots were incapacitated and the aircraft ran out of fuel. I had my ideas but there is nothing like seeing it for "real" so we tried this in a 777-2 full motion zero flight time approved simulator.
We used a zero fuel weight of 175 tonnes. We let it run out of fuel at FL 250 in track hold and alt capture. However it would not make any difference what mode it was in as everything would drop out. In real life one engine uses fractionally more fuel per hour than the other and there is typically a difference between main tanks of a few hundred kilos, so we had a 300 kg difference between the contents of the left and right tank.
When the first engine failed TAC (Thrust asymmetry compensation) automatically applied rudder. The speed reduced from 320 knots indicated to 245 knots indicated. It was able to maintain 245 knots and FL250. When the second engine failed the rudder trim applied by TAC was taken out and the trim went to zero. The autopilot dropped out and the flight controls reverted to direct mode. The speed initially came back to 230 knots but then the nose started to lower. The nose continued to lower and the rate of descent increased to 4,000 feet per minute, the nose kept lowering and the descent rate increased to 7,500 feet per minute with a bank angle that increased to 25 degrees. The speed at this point had increased to 340 knots indicated, above VMO but there was no horn as it was on limited electrics. About this point the RAT (Ram air turbine) chipped in and the CDUs and copilot's PFD (Primary flight display) came alive. The flight controls stayed in direct mode.The eicas screen was full of messages like pitot heat, flight controls, APU fault (The APU had tried to autostart due double engine failure but failed due no fuel to start it) low fuel pressure etc.
Then with a max descent rate of almost 8,000 feet per minute the nose started to slowly rise and keep rising. We had dropped to about FL170 but the nose slowly rose up to 6 degrees pitch up and we started climbing at about 3000 feet per minute and the bank angle reduced to only 5 degrees. It climbed back up to FL210 at which point the speed had come back to 220 knots and then the nose dropped down again and we were soon back to descending at 8000 feet per minute. So basically a series of phugoid oscillations with bank angle between 5 and 25 degrees and pitch attitude between about 9 degrees nose down and 6 degrees pitch up. It was losing about 8000 feet and then gaining about 3 or 4000 feet with airspeed fluctuating between 220 and 340 knots.
We didn't watch it all the way down due time constraints and stopped the experiment at 10,000 feet but it was consistent all the way down. Having watched it I can say with certainty that if the pilots were incapacitated and it ran out of fuel there is no way it could have landed on the water with anything like a survivable impact. Just passing on the info.
We used a zero fuel weight of 175 tonnes. We let it run out of fuel at FL 250 in track hold and alt capture. However it would not make any difference what mode it was in as everything would drop out. In real life one engine uses fractionally more fuel per hour than the other and there is typically a difference between main tanks of a few hundred kilos, so we had a 300 kg difference between the contents of the left and right tank.
When the first engine failed TAC (Thrust asymmetry compensation) automatically applied rudder. The speed reduced from 320 knots indicated to 245 knots indicated. It was able to maintain 245 knots and FL250. When the second engine failed the rudder trim applied by TAC was taken out and the trim went to zero. The autopilot dropped out and the flight controls reverted to direct mode. The speed initially came back to 230 knots but then the nose started to lower. The nose continued to lower and the rate of descent increased to 4,000 feet per minute, the nose kept lowering and the descent rate increased to 7,500 feet per minute with a bank angle that increased to 25 degrees. The speed at this point had increased to 340 knots indicated, above VMO but there was no horn as it was on limited electrics. About this point the RAT (Ram air turbine) chipped in and the CDUs and copilot's PFD (Primary flight display) came alive. The flight controls stayed in direct mode.The eicas screen was full of messages like pitot heat, flight controls, APU fault (The APU had tried to autostart due double engine failure but failed due no fuel to start it) low fuel pressure etc.
Then with a max descent rate of almost 8,000 feet per minute the nose started to slowly rise and keep rising. We had dropped to about FL170 but the nose slowly rose up to 6 degrees pitch up and we started climbing at about 3000 feet per minute and the bank angle reduced to only 5 degrees. It climbed back up to FL210 at which point the speed had come back to 220 knots and then the nose dropped down again and we were soon back to descending at 8000 feet per minute. So basically a series of phugoid oscillations with bank angle between 5 and 25 degrees and pitch attitude between about 9 degrees nose down and 6 degrees pitch up. It was losing about 8000 feet and then gaining about 3 or 4000 feet with airspeed fluctuating between 220 and 340 knots.
We didn't watch it all the way down due time constraints and stopped the experiment at 10,000 feet but it was consistent all the way down. Having watched it I can say with certainty that if the pilots were incapacitated and it ran out of fuel there is no way it could have landed on the water with anything like a survivable impact. Just passing on the info.
Last edited by rampstriker; 8th Apr 2014 at 18:12. Reason: post undeleted
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Working together
> but remember the two navies have worked together before with ship under way and other live fire exercises so it is not totally new to each other.
But that doesn't rule out that they have have differing agendas and must maintain a competitive stance toward each other. Different branches of militaries within a single nation do that all the time so it is a virtual certainty that comaraderie between nations is incomplete.
But that doesn't rule out that they have have differing agendas and must maintain a competitive stance toward each other. Different branches of militaries within a single nation do that all the time so it is a virtual certainty that comaraderie between nations is incomplete.
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Taking into account the post from Rampstriker, the phugoid oscillations could in affect account for the claims of the plane being flown below 5000ft as reported in the media?? ...it was just on the step down??
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Leightman 957
Yes, certainly (differing agendas). I have said this from day 1.
China is trying to wave the flag in a big way to remove the stain of criticism that it didn't do anything the last time they had an emergency in the region - which stung them badly - and of course play to the domestic side as well.
And of course they want to find the first confirmed debris et al but that doesn't mean the two can't work side by side. I am sure AVM Rt Angus know full well the Chinese agenda having dealt with them for years.
Yes, certainly (differing agendas). I have said this from day 1.
China is trying to wave the flag in a big way to remove the stain of criticism that it didn't do anything the last time they had an emergency in the region - which stung them badly - and of course play to the domestic side as well.
And of course they want to find the first confirmed debris et al but that doesn't mean the two can't work side by side. I am sure AVM Rt Angus know full well the Chinese agenda having dealt with them for years.
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rtd1. an indonesian military chief said " the aircraft was not detected flying over our territory" which is not the same as saying we never saw it. radars often cover large tracts of someone else's territory or airspace under its control and I suppose the convention is that you do not comment on what you have seen going on there. ditto malaysia,
they reported their last radar contact was at igrex which is at the edge of the malaysian administered airspace.
they reported their last radar contact was at igrex which is at the edge of the malaysian administered airspace.
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Questions on CNN recording
CNN just ran a video with the ULB pings in audio coinciding with a waterfall display. I have been unable to find this on the net - I would have expected it to be at JACC's media documents. Does anyone know if it is available.
The video is quite compelling. You can hear the very regular clicks. On the display, you can sometimes see weaker clicks at different times, which could be the other ULB, or could be natural - I couldn't tell. They mumbled that the clicks were computer generated, whatever that means.
Others here with more sonar experience than me might be able to add to this.
The CNN report is at http://www.cnn.com/2014/04/08/world/...html?hpt=hp_t1
[Note: other link went bad, edited for new one. This shows much less of the pings, but it is there]
The video is quite compelling. You can hear the very regular clicks. On the display, you can sometimes see weaker clicks at different times, which could be the other ULB, or could be natural - I couldn't tell. They mumbled that the clicks were computer generated, whatever that means.
Others here with more sonar experience than me might be able to add to this.
The CNN report is at http://www.cnn.com/2014/04/08/world/...html?hpt=hp_t1
[Note: other link went bad, edited for new one. This shows much less of the pings, but it is there]
Last edited by Mesoman; 8th Apr 2014 at 20:20. Reason: Link rot - providing new one
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I have been unable to find this on the net - I would have expected it to be at JACC's media documents.
http://www.pprune.org/rumours-news/5...ml#post8423003
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CNN just ran a video with the ULB pings in audio coinciding with a waterfall display. I have been unable to find this on the net - I would have expected it to be at JACC's media documents. Does anyone know if it is available.
The video is quite compelling. You can hear the very regular clicks. On the display, you can sometimes see weaker clicks at different times, which could be the other ULB, or could be natural - I couldn't tell. They mumbled that the clicks were computer generated, whatever that means.
Others here with more sonar experience than me might be able to add to this.
The CNN report is at U.S. Navy on MH370 search: We are cautiously optimistic - CNN.com Video
The video is quite compelling. You can hear the very regular clicks. On the display, you can sometimes see weaker clicks at different times, which could be the other ULB, or could be natural - I couldn't tell. They mumbled that the clicks were computer generated, whatever that means.
Others here with more sonar experience than me might be able to add to this.
The CNN report is at U.S. Navy on MH370 search: We are cautiously optimistic - CNN.com Video
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CNN "Waterfall" display with audio
Search teams fail to relocate pingers in Flight 370 search - CNN.com Video
Shows the waterfall display "at work" with what is claimed to be the actual audio released by the Australians.
In another CNN item there is a statement that one of the detections was a sound that originated from their own boat, but I cannot work out which it was. I guess it was the "RIB" detection.
Shows the waterfall display "at work" with what is claimed to be the actual audio released by the Australians.
In another CNN item there is a statement that one of the detections was a sound that originated from their own boat, but I cannot work out which it was. I guess it was the "RIB" detection.
Would the pinger from the recorder be picked up by a warships asdic set or is it a different ball game?
SONAR on warships would have a low probability of detecting that pinger. See a few dozen posts covering "why" earlier in the thread. Short answer: frequency band and range.
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My posts normally get deleted, and this post is not going to help anybody out in any way, but earlier today I decided to start from the beginning and read the first 15-20 pages of posts on this thread. It's quite interesting to see the information along with absurd rumors that were coming in at the time. It's also very interesting to just sense the general mood at that time compared to now. It's also quite haunting to go back and see how sure everybody was that everything involving with this plane would be completely figured out within a short period of time, unbeknownst that we'd still be here exactly one month later still grasping at straws for the most part. If you've got a few minutes I suggest you try for yourself
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"Ocean Shield" - Grid Search
The graphic below shows some of the AIS position reports received in the last two days.
The Red tracks are nominally 203°T , the Yellow tracks 024°T, and the most recent Green track is 293°T. The TPL towing has been carried out at 2.0 KTS at all times, with small increases of speed showing up during the turn and realigning phases.
Though the JACC aren't saying anything at this stage, it appears that an attempt is being made to triangulate and localize detected pings.
EDIT: Updated graphic
The Red tracks are nominally 203°T , the Yellow tracks 024°T, and the most recent Green track is 293°T. The TPL towing has been carried out at 2.0 KTS at all times, with small increases of speed showing up during the turn and realigning phases.
Though the JACC aren't saying anything at this stage, it appears that an attempt is being made to triangulate and localize detected pings.
EDIT: Updated graphic
Last edited by mm43; 9th Apr 2014 at 01:14. Reason: Added time of last position