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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 20th Mar 2014, 20:27
  #6701 (permalink)  
 
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Did any facility SECAL the plane at any time?
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Old 20th Mar 2014, 20:28
  #6702 (permalink)  
 
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Article on the buoys being dropped from the C-130 with photos
from the C-130.

Missing Malaysia Airlines plane: RAAF narrows search field as hunt for MH370 continues
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Old 20th Mar 2014, 20:30
  #6703 (permalink)  
 
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Staggerwing`s question on radar.

Shipborne military naval radar is horizon limited and relies on sat link for enhanced range and altitude. Airborne radar, such as EWAC is the current fashion. The actual numbers are not on general display for obvious reasons, so there is not much more than just the usual theoretical data around. The only useful tool in the area is the Ozzie Jindalee Operational Radar Network, multistatic radar using OTH-B (OVER THE HORIZON ) with an official range of 1900miles.
Here is its coverage, near enough to the current search area.

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Old 20th Mar 2014, 20:31
  #6704 (permalink)  
 
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Circumnavigating Flotsam?

There's another 4-5 hours before daylight in the search area when an a/c crew can get eyes and cameras on the objects the satellite picked up.

Then we will have a better idea whether one or more of the objects came from MH370 or a maritime casualty that's been circumnavigating Antarctica since???

While it's pretty barren North of the Himalayas, before that there's a bunch of high steep heavily vegetated slopes in extremely difficult terrain that could conceal a CFIT.

If it hit the side of a gorge, the debris could possibly fall into a high volume river leaving precious little visible.

Even if the flotsam does not come from MH370, there's still nothing in the public domain to put one ping arc over the other.
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Old 20th Mar 2014, 20:34
  #6705 (permalink)  
 
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USN Naval Radar Info

To answer staggerwing at least for USN assets they would typically have some combination of these air search RADARs depending on the type of ship.

Some common examples:

AN/SPY-1 AN/SPY-1 - Wikipedia, the free encyclopedia

AN/SPS-48 AN/SPS-48 - Wikipedia, the free encyclopedia

AN/SPS-49 AN/SPS-49 - Wikipedia, the free encyclopedia


250nm+ range in general with the SPY-1 and SPS-48 being phased array height finding RADARs.


I have a piece of SPS-49 antenna that I had to cut off with a hacksaw sitting on my desk.
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Old 20th Mar 2014, 20:38
  #6706 (permalink)  
 
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XB70
One question I had was on knowing the turn was entered in the FMC.... was this deduced because the next waypoint was seen in ADS data received before shutdown? Has anything specific (lat/long) been divulged?
It would be also interesting to know how ACARS transmitted the information.
If it was VHF, HF or Sat. Maybe the crew forgot at the time to switch off the HF if this was the route out. All 3 can be easily disabled.

If 'they' were going to steal the aircraft then they would most certainly shut it down Before doing anything unusual.

Was it in the secondary in case of emergency and the secondary was activated.

It would seem most odd that highly experienced operators would overlook such obvious detail to put the aircraft into 'stealth' mode.
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Old 20th Mar 2014, 20:48
  #6707 (permalink)  
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Originally Posted by Staggerwing View Post
Hunter 58,

Early in this blog, I made a post concerning radar tracking by naval vessels that may have been close to the flight path of the aircraft. I did not receive a reply from anyone at the time and maybe you could answer the question: would naval vessels be able to track the aircraft using primary returns and, if so, what would be the range if the aircraft remained at a FL greater than FL200?

I was assuming that there would have been some naval vessels, from various countries, operating somewhere in the area believed to have been overflown by the aircraft.
Last bit first, probably not.

Then ability to track depends on the type of ship as air search is a specialised role usually for destroyers, cruisers and carriers. Smaller vessels, such as patrol boats and up to frigates will not usually have an air search capability and would rely on data links for a recognised air picture. The RAP would only be available if they were in a link with other air defence units, ships and AWACS. It that part of the world, unless on operations or exercises, it would be unlikely that there would have been any real chance of ships being present and detecting 370.

Other than units on operations, many navies operate on a day running basis and certainly expect a weekend in port.
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Old 20th Mar 2014, 20:49
  #6708 (permalink)  
 
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To Whom It May Concern. Black Box 37.5 khz Pings Are Ultra-sonic!

I wrote about this earlier in the forum, but now that it seems there's a good chance there's a legitimate search area, I want to reiterate that submarines and P-3's are set up for listening for submarines, ships, explosions, Say Again Machines, etc, but not optimized for the ultra-sonic 37.5 khz audible ping sent by black boxes. Maybe there are some submariners or P-3 crew that can comment about this. I've read somewhere that an 8 khz ping, would be optimum for typical submarine or P-3 equipment to hear. I know it's redundant to call a 37.5khz ping "ultra-sonic" but I want to emphasize that point. You can't hear it without a dog or down converter. If the equipment has the range, you can look at it on a spectrum analyzer. Just like radio equipment is more sensitive when tuned to a specific RF frequency, listening equipment is much more sensitive when tuned for a specific audio frequency, instead of listening to a broad range of frequencies. This may have been why AF447's ping wasn't heard or not heard consistently enough.
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Old 20th Mar 2014, 20:50
  #6709 (permalink)  
 
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http://www.c-130hercules.net/gallery...1/0/5/3572.jpg

Sometimes the aircraft stays together and floats for days.
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Old 20th Mar 2014, 21:09
  #6710 (permalink)  
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Chronus, very interesting map. Did not know it was available as normally OTH radar technology actual operational range is not public domain.

As there is not really much ( if any) traffic flying southbound in this area on that route, it should be relatively easy to look at the tapes to see if an echo existed at the time.
Or the aircraft ( if indeed there was one there ) flew exactly outside of the operational range, reimforcing the idea that this route was not chosen at random .
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Old 20th Mar 2014, 21:12
  #6711 (permalink)  

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I have a general problem with the southern search area.

Altough we have no confirmed track across the peninsula we do have received information regarding the general direction of the aircraft. If was reported to have crossed the peninsula on a southwesterly direction to then turn to a northwesterly direction.

The above could be explained in a catastrophic event with a direct-to entry followed by a heading mode.

Hovever, to then go to a southern route you would require some human intervention. And such intervention comes very late for 'cabin survivors'.

As a consequence the southern route is not possible in the event of a catastrophic failure.
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Old 20th Mar 2014, 21:16
  #6712 (permalink)  
 
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@FE Hoppy
CVR 2 hours
FDR 25 hours


It is amazing that a computer in a home you may buy for your teenage kid can outperform the storage available in a modern airliner by more than a 1000 factor.
2 hours of voice recording on a plane that may be designed to fly 16-18 hours?
In case of MH370 which may have flown for up to 8 hours and if so the voice recordings in the first two hours maybe a lot more important than the last two hours. Especially if (at least) one pilot was incapacitated for whatever reason.

The best I can gather is that the audio quality of the CVR used today is 31 kbps.
A 1TB SSD recording at 64 kbps will can store more than 72000 hours (1 channel)at twice the quality.
I believe current CVR's use either 3 or 4 channels, but even using 10 channels (some in the cabin as well), 7200 hours equals 300 days.
Based on the assumption that a CVR and a FDR use the same storage media with the FDR yielding ~12 times duration of a 4-channel CVR a 1 TB SSD would store 9000 days of data (the life of most airframes) ... all for under $1,000 (excluding DAQ which would likely be the same as current recorders).
Using the same storage media (1TB SSD), the use of 10 video cameras in full motion mode would record 40 hours of video.

Time to use current technology, methinks
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Old 20th Mar 2014, 21:18
  #6713 (permalink)  
 
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Hunter, Inmarsat puts it on the red arc at 0811. That's not consistent with traveling in a straight line SW over Malaya. Either the SW report over Malaya is wrong, or extra turns were required.

In either case, I'd bet on Inmarsat being right, and the zigzagging over the NE Indian Ocean being a bit suspect.
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Old 20th Mar 2014, 21:23
  #6714 (permalink)  
 
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Originally Posted by Pontius Navigator View Post
PS, there were two of us talking about it. The 'as normal chatting' would have been as perceived by the subject. Trust me when I say they would have been talking scribble as well as writing it.

I was usually one of the first back on oxygen and saw some trying ineffectually to stop the doctor putting their mask back on. You see their pencil 'scribbling' but in reality just doing nothing.

Automatic reflexes no chance.
That was me in the decompression chamber with a compatriot who appeared to be unaffected until we checked - remember this was just over 30 seconds - he was writing perfectly neat garbage and was not 'responsive' to the instructor who got his O2 back on rapidly. I cannot see anyone at 35,000 with hypoxia doing/saying anything sensible after a few seconds.

It would be most instructive to know what the controller said to the crew, a chatty non-standard handoff could get an "alright goodnight" in response.
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Old 20th Mar 2014, 21:25
  #6715 (permalink)  
 
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Post 6725 Ole Ole: More thoughts on ping accuracy
- Inmarsat-C uses TDM (time division multiplexing).
- Symbol duration within the time slots is 8.64s/10368 symbols = 833 microseconds per symbol

Transmissions in adjacent time slots have to arrive at the receiver (satellite) within the accuracy of one symbol. => Propagation delay has to be known with min. accuracy of 833 microseconds which is corresponds to 250km.

That is imho the upper error margin for the ping accuracy. For reasons given earlier I'm still optimistic accuracy is far better.

The arcs with greater radius have more favorable geometry thus accuracy is better further out. Think cutting a tomato (earth) into slices. Put the tomato to the far left of the cutting board and imagine the satellite to the far right. Each cut through the tomato marks points that are equidistant to the satellite. The skin of the slices is the set of points on the surface that lie within the error margin. The outer slices (those closer to the satellite) have more skin, i.e bigger error.

Stand to be corrected.
No correction here, but compliments on the great tomato teaching analogy. CDMA would be better for the satellite to use than time division, since propagation delay does not affect it as much, since the bits know how to put themselves back in order at their destination, since they are encoded in a Walsh Code. Of course, it's not easy to upgrade a satellite as well as the many customer transceivers, unless they have an up-loadable modulation format. So it's probably just academic. Maybe the next set of satellites and customer equipment will have CDMA modulation. Of course, the very nature of time division multiplexing may make it easier to use the shift in the spaces between the bits, as the customer moves, for tracking purposes.
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Old 20th Mar 2014, 21:26
  #6716 (permalink)  
 
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Sorry, but I disagree. The whole lesson of eventually finding AF447 was the "Bayesian" theory.

Each piece of information is evaluated, given a probability and move on from there. As with AF447, the "LKP" is often accurate, even if other info suggests otherwise. The Inmarsat info would have been evaluated, given a probability, but not straight away, enough weight to call off the other search areas.

There is also some practicality. The assets available cannot all be switched to/from areas at will.

I think it is also clear the search teams / location have been a day or 2 ahead of what we are told the "latest" info is i.e. as info comes in, someone is evaluating and actioning it. Just not the chap in front of the cameras

Edit: reading a bit more on it, you concentrate on where you are most likely to find it. That is not the same as where you think it most likely is! The original search was in shallow water, and a small area... so if it was there, the P of finding it is much higher than the deep / enormous South Indian Ocean. The former search has now stopped since not only is the P higher it is in the Indian Ocean (or the N), but since the South China Sea has been so extensively searched, the P of now finding it there goes down. Or something like that!
My point is the second one, why are they searching at some calculated end of the arc rather than along it. It isn't known what speed the aircraft was flying at. They've highlighted a search area for Australia that is at the end of the aircrafts fuel range, at some assumed cruise speed. All they know is that the transmissions were received somewhere in the arc (north or south) during those time periods. It could have been circling a single point and remained in the width of the arc and the width is not a line, it has a width due to the lack of precision of the sat data. Remember the arc is NOT a track of the aircraft. The entire arc should be given the same POD until proven otherwise.
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Old 20th Mar 2014, 21:26
  #6717 (permalink)  

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Hunter, Inmarsat puts it on the red arc at 0811. That's not consistent with traveling in a straight line SW over Malaya. Either the SW report over Malaya is wrong, or extra turns were required.

In either case, I'd bet on Inmarsat being right, and the zigzagging over the NE Indian Ocean being a bit suspect.
Now I am more than confused.

The reports are that the left turn brought the aircraft in an SW direction before turning NW after crossing the peninsula. The zigzag was never reported and is contrary to indonesian reports. None of this says anything about the 0811 ping.

My point is that the northern location would be consistant in an catastrophy assumption. But it is not possible in a southern location as someone would have to get the aircraft out of the NW heading.
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Old 20th Mar 2014, 21:33
  #6718 (permalink)  
 
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Size is not everything dear!

It is amazing that a computer in a home you may buy for your teenage kid can outperform the storage available in a modern airliner by more than a 1000 factor.
2 hours of voice recording on a plane that may be designed to fly 16-18 hours?
In case of MH370 which may have flown for up to 8 hours and if so the voice recordings in the first two hours maybe a lot more important than the last two hours. Especially if (at least) one pilot was incapacitated for whatever reason.

The best I can gather is that the audio quality of the CVR used today is 31 kbps.
A 1TB SSD recording at 64 kbps will can store more than 72000 hours (1 channel)at twice the quality.
I believe current CVR's use either 3 or 4 channels, but even using 10 channels (some in the cabin as well), 7200 hours equals 300 days.
Based on the assumption that a CVR and a FDR use the same storage media with the FDR yielding ~12 times duration of a 4-channel CVR a 1 TB SSD would store 9000 days of data (the life of most airframes) ... all for under $1,000 (excluding DAQ which would likely be the same as current recorders).
Using the same storage media (1TB SSD), the use of 10 video cameras in full motion mode would record 40 hours of video.

Time to use current technology, methinks
State of the art technology does not have to be safe to be installed in your teenage kids' PC. Failures are an inconvenience not a disaster.

Keeping safety critical systems safe means they may run a generation (or two) behind the latest capabilities. That is not a bad thing.

Let's face it, using "current technology" batteries in aircraft has created a few issues recently.
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Old 20th Mar 2014, 21:38
  #6719 (permalink)  
 
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ULB Detection

Back in one of the earlier AF447 threads, auv-ee explained in detail the detection range of the 37.5kHz ULB pinger.

The maximum detection range is 2 - 3km, and in rather calm sea conditions. Less than 1800 meters will provide a 90% or better chance of detection. All this is described in detail by one who knows and has the experience to go with it.
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Old 20th Mar 2014, 21:41
  #6720 (permalink)  
 
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Hunter,

While it could be anywhere on the red arc at 0811, Inmarsat sensibly curtailed the arc at a spot in the Indian Ocean that is the number of flight hours multiplied by a reasonable speed from the South China Sea. They presumably have several earlier hours of angle measurements too, which would be consistent with that.

It seems unlikely to me that the Australian government would make such a big deal about going to look in that oceanic box unless they had some good information that looking in that box was likely to pay off.

The biggest problem with the northern route is that someone somewhere should have seen it co,ing, whereas going south there's nothing to bump into.

The earlier Inmarsat ping angles would show whether or not a steady straight flight into the void was consistent with them. I trust the heavy Australian search is based on sound information, although their released pictures of the "ocean objects" are very whitecap-looking to me. The radar shenanigans and turns over SE Asia all seems to be pretty random.
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