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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 5th Jun 2014, 13:09
  #10941 (permalink)  
 
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Originally Posted by DespairingTraveller
I was a bit surprised to read that paragraph, as I had been under the impression that ACARS was VHF only on this flight. Like others, I've also been under the impression that the 1:07:49 message was a routine engine report.
I suspect that the report conflates the Satcom infrastructure (which logged twice in flight, and is the source of the pings), with the ACARS system (which provides store and forward text and data messaging from the flight deck and various aircraft systems). But ultimately, it is irrelevant in that we know when the last ACARS message was transmitted and we know the Satcom infrastructre was connected for many hours after that.

IanW,
Understood - My point was more on the logoff side. It doesn't appear that either system (SatCom or the ACARS store/forward network) have any intrinsic need to have a logoff function. From those with more technical knowledge, is there a logoff message the would or would not be expected in certain circumstances?

I have believed that both are like a transponder in that you know it is not 'on' when it stops responding/sending rather than something like a logout messaging being sent. As such, it is not possible to to deduce the 'Why' from a loss of ACARS or Satcom (or transponder) data. It is intinguishable between the device being shut down in a controlled way (i.e turned off in the normal way), suddenly issolated from power, failed, or destroyed.
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Old 5th Jun 2014, 13:29
  #10942 (permalink)  
 
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logon and logoff

I think you will find that the reason for a logon and log off is so that the network knows the aircraft is available to receive traffic in the ground - air direction.
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Old 5th Jun 2014, 15:39
  #10943 (permalink)  
 
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Can't work out how to paste the image here.

I have calculated the solar terminator for 0018 UTC on March 8 2014, and the link below seems to work.

http://www.timeanddate.com/scripts/s...=20140308T0018


So if plan was to ditch around first light, this would suggest a long way SW along the final (7th) arc. Somewhere close to the initial air search area a long way WSW of Perth.

The further NE along the 7th arc the flight ended, the longer the plane was flying in daylight.

Last edited by slats11; 5th Jun 2014 at 15:55.
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Old 5th Jun 2014, 17:44
  #10944 (permalink)  
 
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The level of presumption here is really quite surprising. Tim Clark, President of the company that operates the largest B-777 fleet, and might just have access that we don't mentions, in an apparent off-the-cuff interview, that there were three things that his qualified crews would not know how to do, THAT WERE DONE and the presumption here is - OH! he must mean VHF com, Transponder(s), and ACARS? So how many 777 qualified pilots don't know how to manage those things? For example, do all aircrew know how to access the flight deck of an aircraft to which they are not assigned?

Isn't it time for a reality check?

Clearly, there is something else and I suspect that as a major operator with the responsibility he has, Mr Clark may know more that he can openly say? So what you, or we, should really be thinking about is what three things could have contributed to the loss of this aircraft that aircrew would not likely know about,but others might? And why is it he assumes that this knowlege boarded the flight and could do so again? Seems to discount all of those fire theories, meteors and structural failure too.

There are far more important issues in play here than LF noise picked up on hydraphones and an anxious lady sailor seeing an aircraft in the early dawn (when it is still dark at sea-level).

It seems that Tim Clark is still asking exactly what was below deck in the hold; amongst other things? That seems to have been brushed aside; as soon as someone found batteries. What else is there that remains unknown about the freight and the people onboard?

Why, then, is it assumed all will be known once the aircraft is found, if it is? Just what do you think the DFDR will reveal about the how and why?

It is time to stop sweating the small stuff and consider the bigger picture.
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Old 5th Jun 2014, 19:39
  #10945 (permalink)  
 
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Astra Mike makes a good point in closing:

quote "It is time to stop sweating the small stuff and consider the bigger picture"

The big picture now is the 29th May press release by JACC, where we are informed the next steps are as follows:

1. A review of all existing information and analysis to define a search zone of up to 60,000 square kilometres along the arc in the southern Indian Ocean.
2.Conducting a bathymetric survey to map the sea floor in the defined search area.
3. Acquiring the specialist services required for a comprehensive search of the sea floor in that area.

Simply put, this means.
1. Try and decide where to look next, then having made up their minds where to look,
2. have a peep to see where it is flat and where it is not, then
3. get the boys and their equipment on site.

It will take them till end of August to do No1 and at least another 12 months to do the rest.

Could it be that in the interim some debris may wash up on someone`s shores.
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Old 5th Jun 2014, 21:41
  #10946 (permalink)  
 
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AstraMike writes, "The level of presumption here is really quite surprising." Well, that's the nature of investigation into mysteries, collecting data and trying to fit the bits of the jigsaw together, ideas followed by testing against reality.

You presume that Clark is an authority and hiding stuff, rather than accept what he says at face value.
“this aircraft was disabled in three primary systems. To be able to disable those requires a knowledge of the system which even our pilots don’t know how to do. Somebody got on board and knew exactly what they were up to.”
Well, we know it wasn't engine management, control surfaces or undercarriage he is talking about. I put Clark into the same category as many other highly paid executives.

I would suggest no Emirates pilots have disappeared with a B777, not because they can't, but because so far, none of them have wanted to. Professionalism, stability and a stake in the community.

We're not permitted to talk about the different cultures (including their religions), formerly called races, their attitude to life and other individuals ...
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Old 5th Jun 2014, 22:38
  #10947 (permalink)  
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Marty

Glide from 35,000ft?

Less than 15 mins.
At 320 kts or so you might be correct - however at best glide speed you would be wildly out.
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Old 5th Jun 2014, 23:35
  #10948 (permalink)  
 
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Originally Posted by GobonaStick
This map posted by the witness seems to point to 05:00 (time zone unclear), assuming the section highlighted is where the sighting took place.
The timezone was most likely UTC+8 (the software her husband used to create the plot uses local time), in which case that section of the plot missed MH370 by a couple of hours or so.

However since the yacht only does 3 knots so it would definitely been possible to see the airplane assuming that the ATSB estimated track is correct.

At 02:50 the yacht was on a northern tack so MH370 would have appeared over the bow, then swung around the port side and disappeared off to the stern. Her eyewitness account saw something over the stern and traveling from port to starboard, so that would be West to East, completely wrong for MH370

As for what she saw it was dawn so it may have been a plane catching the red glow of sunrise. The 'other aircraft' she saw could have be low-earth orbit satellites, which would have been clearly visible at that time of day.
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Old 6th Jun 2014, 08:33
  #10949 (permalink)  
 
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Can't imagine it would be a fighter, Gob, why would anyone send up a fighter on full burn to chase an unidentified primary target brushing up against a sensitive military area?
Well, it clearly didn't catch up with it, did it. I'd file this bright idea with the claim by the lawyer brother of Kiwi Paul Weeks lost on the flight, "It's either incompetency or a cover-up." Wouldn't just be that this caught everybody napping, nobody had a clue what happened or where it went...
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Old 6th Jun 2014, 08:35
  #10950 (permalink)  
 
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"Possible turn" at about 18:25?

18:22 Last primary radar contact, aircraft heading NW
18:25 Log-on request initiated from the aircraft terminal
18:28 First 'handshake' arc, BTO and BFO indicate aircraft heading south

Between 18:25 and 18:28 there were 4 exchanges between the ground terminal and the aircraft terminal. The recorded BTO and BFO values for those exchanges varied considerably, which may be attributed to either the non-stabilized operation of the aircraft terminal or the turning of the aircraft. After 18:28 the BTO and BFO values consistently indicate a southern heading, so there must have been a turn after the last radar contact. Between the first and the sixth arc the BTO and BFO values show a steady progression, then there is another 'jump' to the final arc. The final arc is from a log-on request initiated from the aircraft, probably after a power interruption.

EDIT:
The 'jump' between the sixth and the seventh arc may have been due to the airplane descending at the time of the seventh arc.

Last edited by Gysbreght; 8th Jun 2014 at 10:35.
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Old 6th Jun 2014, 10:07
  #10951 (permalink)  
 
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Katherine states on page 6 of her thread that:


'The GPS time updates automatically. At no stage did we move beyond Thailand time. I don't know when it switched to Thailand time.'

Last edited by susier; 6th Jun 2014 at 10:29. Reason: Pontius is right
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Old 6th Jun 2014, 11:49
  #10952 (permalink)  
 
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The GPS track of the yacht was exported almost 3 months after being recorded (when the skipper wrote up the journey for a blog). The track would have been recorded in UTC but the skipper exported it in local time of the location where he wrote the blog. I think he was only interested in the track for the purposes of plotting a map and at the time didn't care about timestamps.

He doesn't seem to be talking online about the incident (in my view probably quite wise) and his wife is so bad at communicating facts that probably only a forensic analysis of the recorded data files would reveal the truth.

But in any case what's the point? She only filed a report after armchair experts elsewhere noticed that the yacht had been close to the estimated aircraft track. Up until then she hadn't connected the two events. It was dawn, she saw strange colours and that time of day always creates unusual lighting effects in the sky).

Had she kept a diary and filed a report sooner it may have helped the ATSB with it's construction of an estimated flight path. As it is her story, even if true, adds absolutely nothing to the investigation.
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Old 6th Jun 2014, 17:01
  #10953 (permalink)  
 
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exeng

From FL350, you'll travel about 85nm. At Vmd (ca 240kt IAS), you'll set off at about 410kt TAS. By FL150, your TAS will have dropped to about 300kt. For tha complete descent your average TAS will decrease from about 7nm per min at TOD, down to 4 nm per min as you reach the Indian Ocean.

You'll do those 85 miles in about 15 mins.

At Vmd.
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Old 7th Jun 2014, 07:40
  #10954 (permalink)  
 
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Originally Posted by martynemh
From FL350, you'll travel about 85nm. At Vmd (ca 240kt IAS), you'll set off at about 410kt TAS. By FL150, your TAS will have dropped to about 300kt. For tha complete descent your average TAS will decrease from about 7nm per min at TOD, down to 4 nm per min as you reach the Indian Ocean.

You'll do those 85 miles in about 15 mins.

At Vmd.
That is based on a lot of assumptions. Such as a pilot controlling the aircraft descent. Several thousand posts back someone reported testing an uncontrolled engine off descent in the SIM and reported a series of phugoids rather than a controlled descent. If a pilot is assumed then perhaps a dive maintaining speed to provide some controllablility at low level for a minimum wreckage ditching.
Or to put it another way, we are dealing with SWAG, anywhere within maximum glide range of the last 'Ping' position could be the ocean entry point. It could even be under the last ping if 'the pilot' had spiralled down
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Old 7th Jun 2014, 07:48
  #10955 (permalink)  
 
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Ian W

I agree. The original discussion centred on how long it would take to glide from FL350 to sea level. Anything other than a controlled descent at or about Vmd would take less time.

I should have said 'not more than' 15 mins or 85nm or so.

Last edited by martynemh; 7th Jun 2014 at 08:19. Reason: expression as distance, as well as time.
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Old 7th Jun 2014, 09:19
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Ian W,

Just to be pedantic, and while there is not much else to discuss -

In a phugoid the airplane maintains an approximately constant AoA, i.e. constant L/D. While it is cyclically exchanging potential and kinetic energy, it does not lose total energy more rapidly than in a constant-speed descent, so the total range and time would not be affected.
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Old 7th Jun 2014, 09:37
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I agree. The original discussion centred on how long it would take to glide from FL350 to sea level. Anything other than a controlled descent at or about Vmd would take less time.

I should have said 'not more than' 15 mins or 85nm or so.

Maybe that's the case with the engines failed producing no thrust at all but only drag, but on idle thrust the time to glide from FL350 to sea level would exceed 20 minutes at Vmd at low weights (I know, low weight doesn't really influence gliding distance significantly but it doest influence gliding time).

If it really was an intentional glide I see no reason why the glide would have been conducted with engines failed due to fuel starvation rather than very low fuel remaining.
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Old 7th Jun 2014, 10:09
  #10958 (permalink)  
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exosphere:


If it really was an intentional glide I see no reason why the glide would have been conducted with engines failed due to fuel starvation rather than very low fuel remaining.
Just another "what if."
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Old 7th Jun 2014, 15:03
  #10959 (permalink)  
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Looks Can Deceive.

With reference to the woman who may have seen the flight from a boat. I've been around aircraft all my life, but back in the 1990's, an odd incident occurred which illustrates a point;-
One summers afternoon, a friend rushed into my house to tell me to 'come and see the plane on fire'. Hastily going outside, my perception was of a light-aircraft at perhaps 500 - 800' agl coming towards me soundlessly. I could see the flames licking around the fuselage. However, after perhaps 15 secs, I realised that something was very wrong with my perception. There was still no sound, and the a/c wasn't any closer.... I then realised that the a/c was MUCH further away and very high. Later, radio and TV reports told of people about 70m away reporting it as 'overhead.....so it was very high. Many thousands of people saw it. (ATC at Birmingham reported no plot. There was much speculation, UFO, SR71, Aurora, you name it, not that it's relevant here.)
What was so amazing was how convincing the a/c was at looking much MUCH closer. It had something to do with the speed of the movement of the flames.
Whilst I'm not supporting her report directly, I am saying that, in clear air, flames, even at a great distance can look MUCH closer. My point is that a seasoned observer can be deceived, then it may explain a 'lay' witness not describing that which we 'expect' them to see, as I can attest.
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Old 7th Jun 2014, 19:46
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Does anyone know why the USN pinger locator system doesn't use an array of transducers to determine the bearing to the back box acoustic pinger? There are many commercially available systems which use transponders to measure range and bearing to determine positions of underwater targets like ROV's. You can't get range from a free running pinger but you can get bearing. An example Ultra Short Base Line (USBL) system is covered in the link below.

USBL - All Systems

From the description.

"The second is that the bearing can be determined by knowing the discreet difference in phase between the reception of the signal at the multiple transducers present in the transceiver. This allows the USBL system to determine a time-phase difference for each transducer and therefore calculate the angle of the arriving signal."

All you would need is a compass on the fish along with the derived angle to get the bearing. This would allow the pinger to be found MUCH faster. Using a single transducer seems to be very inefficient.
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