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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 30th Jun 2014, 20:37
  #11221 (permalink)  
 
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The -300ER triple has no CB's on the overhead to remove power from the FDR. It receives all information from AIMS L/R. I am not aware of any alternate inputs to the FDR. Having both AIMS fail is very unlikely though the AIMS CB's are on the overhead.
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Old 30th Jun 2014, 20:58
  #11222 (permalink)  
 
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MH370: New evidence of cockpit tampering as investigation into missing plane continues - Telegraph
A report released by Australian air crash investigators has revealed that the missing Boeing 777 suffered a mysterious power outage during the early stages of its flight, which experts believe could be part of an attempt to avoid radar detection.
I thought this would have been discussed on here yesterday. Or perhaps the posts were deleted...
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Old 30th Jun 2014, 21:02
  #11223 (permalink)  
 
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That green rhumb line which just touches the top of the high probability area coincides exactly with a rough plot I made on Google Earth using some information about the ping arc diameters and a set of assumptions about how I think the track looks at the northern end.

Thank you for posting that.
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Old 30th Jun 2014, 21:40
  #11224 (permalink)  
 
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Surely though, BEDAX would be a better choice of starting point?
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Old 1st Jul 2014, 07:26
  #11225 (permalink)  
 
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The -300ER triple has no CB's on the overhead to remove power from the FDR. It receives all information from AIMS L/R. I am not aware of any alternate inputs to the FDR. Having both AIMS fail is very unlikely though the AIMS CB's are on the overhead.
MH370 was no -300ER.
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Old 1st Jul 2014, 12:53
  #11226 (permalink)  
 
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Originally Posted by Ornis View Post
MH370: New evidence of cockpit tampering as investigation into missing plane continues - Telegraph

I thought this would have been discussed on here yesterday. Or perhaps the posts were deleted...
Form that article, a succinct summary:

Asked whether the power interruption could have been caused by a mechanical fault, Mr Gleave said: "There are credible mechanical failures that could cause it. But you would not then fly along for hundreds of miles and disappear in the Indian Ocean."
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Old 1st Jul 2014, 18:23
  #11227 (permalink)  
 
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I think we should be interested in seeing the outputs from both simple and monte-carlo models here. They certainly interest me, and the clustering of the high probability tracks is quite significant. I look at it like this: Every approach shown to be wrong has potential to remove distraction and complexity from the solution. Every approach not shown to be wrong, adds to the information we have about likely course solutions. I don't think it's a contest, just a process of elimination.
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Old 1st Jul 2014, 18:42
  #11228 (permalink)  
 
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The BFO is surely not the sole discriminant. If course and heading change, you need an explanation for that. The presence or absence of such an explanation would also therefore be a discriminant.
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Old 1st Jul 2014, 18:56
  #11229 (permalink)  
 
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I know but the differences between the -200ER and -300ER for this particular topic (FDR and how it is connected / powered in a ER 777) are few.
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Old 2nd Jul 2014, 00:02
  #11230 (permalink)  
 
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Cockpit tampering?

The report in the Telegraph suggests that the satcom reboot implies some sort of mischief in the cockpit. Isolating all nonessential systems is also very close to the top of the 'smoke in the cabin' checklist. Communications with the ground give no indication as to why anyone would start executing that checklist, but it's probably something every wannabe pilot has tried in their simulator. Whether it was a real or perceived emergency or a ploy to clear the cockpit is a matter for speculation, but I would think the knowledge of (more or less) how to do it would be fairly common in the aviation community.
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Old 2nd Jul 2014, 12:10
  #11231 (permalink)  
 
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Originally Posted by GobonaStick
Quote:
Isolating all nonessential systems is also very close to the top of the 'smoke in the cabin' checklist
An hour after you've decided you're not flying to Beijing?
We don't have an exact time for when the power went off. We only know when power to the Satcom terminal resumed: 18:25 UTC.

The previous Satcom terminal handshake was at 17:07 UTC.

There was no response to Boeings Ground to Air ACARS request at 18:03 UTC so we can most likely guess that the power to the Satcom terminal was off then.

That leaves a period of 56 minutes where we have no idea if the Satcom terminal was powered or not.
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Old 2nd Jul 2014, 12:22
  #11232 (permalink)  
 
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SpannerInTheWerks says:

"I suggest this Thread is held until any relevant further information is received?!

Nothing worthwhile is being added at the moment."

Gotta agree - nothing but conjecture and speculation is being added, and none of it (at this point) can be considered helpful.

In my humble opinion, anyway . . .
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Old 2nd Jul 2014, 15:53
  #11233 (permalink)  
 
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Agree wholeheartedly that this thread should be locked and a new one started once new information becomes available.

The Mods did exactly that (more than once) during the AF447 loss and it was both effective and appreciated.
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Old 2nd Jul 2014, 16:25
  #11234 (permalink)  

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Hyperveloce
I have tested this for great circles between waypoints (LNAV mode), between BEBIM (and a shifted version to the east) toward 3 destinations: the south pole, the Wilkins airport and NOBEY
I am a retired airline pilot rather than a boffin. It looks to me from the data published that if LNAV is used it is likely that Wilkins (YWKS) was the "destination" or somewhere in that region.

All tracks flown in LNAV however small are G/S not rhumb lines. It would be reasonable to assume that at least for the cruise the aircraft would have flown a constant Mach No. (but not G/S as that is dependent on the upper winds) and changing heading to maintain the G/C track. In which case if you could take the 7th ping arc (use the ATSB yellow arc) and compare the tracks from various waypoints in the north and compare the times to cross the earlier ping arcs. Likewise you should be able to take the last "fix" round about MEKAR and look at the what waypoint(s) tie in with it).

If I was "doing the flight planning" I would have concentrated on the FIR points as turning points as they are handovers between ATC units. Skyvector.com has a good flight planning facility to play around with.
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Old 2nd Jul 2014, 18:59
  #11235 (permalink)  
 
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My understanding of this is very weak but from what I have read there are four sources of navigation information that George might use to hold a course. They are Inertial, magnetic, radio and GPS. It seems that aircraft comms were impaired and the information we have consists of some satellite pings. With no comms, what information is still available to the auto pilot to maintain course?

Can anyone shed some light on the possibilities? My reason for asking about the rhumb lines is that even if all other systems are switched off, a magnetic compass might still provide a heading.
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Old 2nd Jul 2014, 23:44
  #11236 (permalink)  
 
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Ulric,


I'm not a T7 expert, but...


FWIW we used to fly much earlier aircraft between Kano and Jeddah using a single course (C) of 072 or 252 for some 7 hours, on Hadj flights. This was a "Modified Lamberdrome" route, ie. a straight line on a Lambert's projection, between the Standard Parrallels. This gave us a Base leg at Jeddah and very long Finals at Kano.


Following ONE then TWO engines shut down... Others may have more ideas for the 100 -ish mile descent's heading.


This flight from KL would have expected sunrise on the Starboard, ( right) side. NOT the Port ( left).


Something similar, with sunrise in the wrong direction, had happened to G-ALDN, the " Hermes in the Desert", 60 odd years ago.
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Old 3rd Jul 2014, 01:43
  #11237 (permalink)  
 
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Should thread be closed?

I should stress at beginning that I'm not a pilot, professional or otherwise (unless you count PPL 50 yrs ago in a Tiger Moth , open cockpit, no electrical system, no brakes and only air to ground comms a Verey Pistol!!)

However, I do see a reason to keep thread active. What I think I am seeing from authorities is that as finding the aircraft becomes less and less likely, they become more and more definite in attaching blame to the aircrew. This thread does keep things balanced and evidence based. As fellow pilots I think you have a role to protect your colleagues from a rush to judgement unless and until the evidence clearly supports such a judgement.
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Old 3rd Jul 2014, 23:26
  #11238 (permalink)  
 
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Gysbreght,


That looks fairly logical, thank you.
My "100+ miles..." should be Track miles, to allow for the possibility of not maintaining a constant heading, when without engines. ( RAT might help, I suppose.)
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Old 4th Jul 2014, 20:48
  #11239 (permalink)  
 
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Unfortunately, 2nd engine out = short decent

I don't have specific knowledge of the T7 either, but perhaps this would happen:

Following one engine shutdown, the autopilot will maintain heading and altitude. The autothrust will increase thrust on the remaining engine as required to maintain airspeed. If max. climb/cruise thrust is not sufficient to maintain speed, the airplane will slow down, still maintaining altitude. The autopilot will disconnect either when the speed becomes too low, or at the second engine shutdown, if that occurs earlier. With two engines shut down and autopilot off, the airplane will descend at approximately constant airspeed, probably fluctuating around the trimmed speed in a phugoid fashion.
The report says "spiral descent", but the more sensation-hungry posters immediately translate that to "spiral dive".
Gysbreght,
(2nd hand info...)
The B777 simulation results from the last month show that the one engine out case is handled gracefully - TAC (Thrust Asymmetry Control) will keep the plane flying straight. At first airspeed will be sacrificed due to single engine thrust limits. Then, altitude will be sacrificed to maintain airspeed. Eventually, flight will stabilize at an altitude and airspeed combination appropriate for the single engine case. (There are specific max engine limits for single engine operation that 'can' be different from the limits for 2 engine opration.)
An article I found very informative on TAC (beyond reding the manual...)
Thrust Asymmetry Compensation

Things get uglier when the 2nd engine cuts out...
1) TAC will (would?) drop out when it detects that both engines are out.
2) When the engines stop supplying AC power and hydraulic pressure, the hydraulic flight controls (including the TAC-adjusted rudder) will remain locked in place.
3) The Autopilot will drop out (disengage) with the total loss of AC power.
>> This creates a race condition in which the exact sequence of events will determine the flight control settings locked in after power is lost.

The suggestion has been made that the Autopilot would drop out first, with the rudder trip from TAC still fully applied. This would lead to an unfavorable condition while power is out. And, when power returns, the autopilot remains disengaged, so these flight control positions will be maintained.
-- This is what leads to the expectation of a very short glide period. The the plane will begin turning right at 2nd engine flame out, and continue that turn even when power is restored from the APC and/or RAT.
This is most likely the 'spiral decent' mentioned in the June 26th ATSB report.
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Old 5th Jul 2014, 12:58
  #11240 (permalink)  
 
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Can anyone tell me how the "log on" at 18.25 UTC determines that "this" was MAS370 ?

I presume "user data" unique to the satcom equipment ?
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