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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 13th Mar 2014, 22:30
  #2921 (permalink)  
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Originally Posted by FIRESYSOK View Post
I'd suspect, perhaps incorrectly, that a 777-200ER with an airline like MAS would more than likely be kitted with SATCOM.

Just because the airframe in question did not have a particular SATCOM antenna subject to an AD does not mean it didn't have one period.

I would also think the comm system would have to be "logged on" to ensure it was operational on demand.

How would an international airline maintain 'operational control' without SATCOM? VHF/HF voice-data only? Unlikely.
The best I could figure out, 777 has separate locations for SATCOM low-gain and high-gain antennas. MH370 did not have a high-gain antenna, which is why it was not subject to the "fuselage cracking" AD, but it could still have a low-gain antenna for the ultra-low-bandwidth Inmarsat Aero L protocol. It's totally possible that Inmarsat Aero L would involve exchanging periodic standby messages "in background", without anyone noticing. But this is all total speculation at this point and I can't find any concrete data on the exact hardware MH370 had onboard, or on the satellite protocol (that would most likely be proprietary anyway.)
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Old 13th Mar 2014, 22:31
  #2922 (permalink)  
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The White House said the engines were still running four hours after contact was lost.

Obama administration officials later said the new information was that the plane’s engines remained running for approximately four hours after it vanished from radar early Saturday en route from Kuala Lumpur to Beijing
White House: Hunt for missing airliner may extend to Indian Ocean - The Washington Post
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Old 13th Mar 2014, 22:34
  #2923 (permalink)  
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Think you are wrong there. Full CPDLC coverage on the North Atlantic, most parts of which are well out of range of land based receivers. All done by satellite. Many carriers get re-dispatch messages etc out there
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Old 13th Mar 2014, 22:37
  #2924 (permalink)  
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This is engine-status VHF ACARS we're talking about, right? Satellite monitoring of VHF traffic is well within the realm of the possible, but the job is finding the relevant ACARS blocks in what's likely a mountain of noisy signals intelligence data, not to mention getting it approved for release.
This scenario is the one that would seem to make the most sense for why it his taken so long to discover any pings past the loss of the transponder.

Last edited by jehrler; 13th Mar 2014 at 23:01. Reason: typos/clarity
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Old 13th Mar 2014, 22:40
  #2925 (permalink)  
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Some things that I believe are "facts".

1) Engine/airframe data is sent via satellite, specifically the Iridium system
and 2) Iridium, being originally designed as a satellite "cell phone" system, would continually ping satellites, even if data wasn't being sent, or phone calls not made.

So even if Boeing, or the airline, or RR weren't getting data, that doesn't mean that the Iridium network doesn't have a good idea where the aircraft is, pretty much all the time. At least if the hardware was powered up. Even if they didn't have an active Iridium subscription, wouldn't the system keep track of the receiver, if only to be ready to give it a subscription code?

Cell phones ping towers almost constantly so as to maintain a connection in case a phone call is made. The system has to know what tower (or satellite) has the phone in view, so your phone can be made to ring within seconds of a phone call.

Lots of assumptions here, but some lights are coming on.
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Old 13th Mar 2014, 22:41
  #2926 (permalink)  
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Plane Flew For 4 Hours


Based on the Wall St. Journal reporter's accounts, the pinging lasted for four hours, at 30 minute intervals. So there was power and a functioning communication link during that interval. Depending on whether the U.S. can triangulate the location of each ping, that would give an approximate a location at the time of the last ping. That leaves up to a 30 minute flying distance from the point of the last ping.
According to the Journal reporter's radio interview, he mentioned several times that U.S. officials haven't ruled out the plane landing, or crash-landing on land.

This is beginning to look like either a sudden depressurization related pilot incapacitation or pilot initiated deliberate destructive action.
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Old 13th Mar 2014, 22:42
  #2927 (permalink)  
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Jehrler, Even if an aircraft is equipped with satcom equipment to relay ACARS, it's a common mistake to assume, that it's communicating directly with a satellite. Instead, it communicates with a ground station, that relays it up to a satellite. Many areas don't have a ground station near enough to the aircraft, to get a good enough signal. Although technology exists, where commercial passenger planes could communicate directly with satellites, there's a lag in implementation, because it has to be tested to make sure it doesn't cause unexpected problems with other systems on the plane. Then standards have to be agreed upon, so it's usually a long time, between the time a technology comes into existence, and it's implementation on an airliner. Even changing the type of coffee maker in an airliner's galley takes years!
If that is true that is very interesting as it means that calling these SATCOM is really a misnomer. It also makes me wonder why this would be a useful addition for ETOPS aircraft as they would seem to spend a fair amount of time over open and base station free areas?

I just assumed (yes, I know) that when someone discussed SATCOM they were discussing an iridium like service (with the attendant high high costs).
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Old 13th Mar 2014, 22:46
  #2928 (permalink)  
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It is an entirely plausible scenario that US SIGINT satellites picked up ACARS data or any other electronic emission from the jet - and that they are only now working that out.
They can monitor signals as weak as a hand held walkie-talkie from orbit.
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Old 13th Mar 2014, 22:46
  #2929 (permalink)  
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Una Due Tfc:

Think you are wrong there. Full CPDLC coverage on the North Atlantic, most parts of which are well out of range of land based receivers. All done by satellite. Many carriers get re-dispatch messages etc out there"

Una Due Tfc, I Hope you are right. I checked into it how airliners used satcom 4 years ago, so my info is dated. Wow, has it been 4 years? Time passes quickly as you get older. 4 years used to seem to me like centuries! Now, 4 years ago seems like last weekend!
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Old 13th Mar 2014, 22:46
  #2930 (permalink)  
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No cargo manifest yet... anyone something on it?
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Old 13th Mar 2014, 22:51
  #2931 (permalink)  
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Mandatory GPS tracking

It's one thing that Amelia Earhart could vanish without a trace over the Pacific some 77 years ago - but a modern airliner carrying 239 souls in this day and age? (And no matter where, really)

Doesn't it raise the question of mandatory GPS tracking equipment on board all aircraft flying on routes where they will be travelling in airspace not covered by SSR? Or to keep it simple and stupid: All airliners certified for commercial operation?

The bandwidth needed for transmitting what would at the most be an SMS containing the A/C registration number, altitude, speed OTG and coordinates maybe every 2 minutes isn't prohibitively expensive. I'd suspect the cost of this one search for MH370 could pay for the whole shebang for quite some time.

This equipment would have to be somehow NOT connected to the rest of the aircraft's avionics and have an independent back up power supply so as to
be able to operate for ex 5 hours on its own.

It could be jammed of course but at least that would leave the world with a last known position and the knowledge that someone was actively working against being tracked.

Last edited by Backseat Dane; 13th Mar 2014 at 23:11.
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Old 13th Mar 2014, 22:54
  #2932 (permalink)  
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One further bit of "evidence" for the VHF engine monitoring signals being picked up by NSA satellites is that the reporting and the white house both specifically mention that the engines kept running.

If this was just normal satellite pinging being identified then why would they mention the engines running?

However, if the RR VHF transmissions were being picked up by the NSA then they could actually see that the engine diagnostics were the ones doing the pinging and, presumably, they only do that when powered up.
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Old 13th Mar 2014, 22:57
  #2933 (permalink)  
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Indeed, and depending how detailed the diagnostics RR received(ie what angle the variable rotors and stators are at) they would have a rough idea of what altitude the aircraft was at when the data was sent
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Old 13th Mar 2014, 22:58
  #2934 (permalink)  
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'Pings' every half an hour?

(Apologies if already covered.) If the 'pings' were still regular, does that suggest that nothing had malfunctioned on board, i.e. it was reporting as per any normal flight? (That would indicate that conversely, irregular pings would signify an event such as AF447.)

Or is it that the aircraft only attempted to make contact/a report every half an hour?
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Old 13th Mar 2014, 23:03
  #2935 (permalink)  
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MH Experience - Fleet - Boeing 777-200 | Malaysia Airlines

Business Class
Other features and facilities include a light preset 10 minutes massage, an in-seat power outlet for PC and other personal electronic devices, a 10.4-inch touch screen TV, satellite telephone and LED reading light.
This is a strong indicator Malaysa has SATCOMM on board its 772. Their ACARS just doesn't seem to be configured to use it. Whatever equipment they use (inmarsat iridium thuraya etc...) normaly there would be some kind of keep alive protocol between airborne transceiver and the communication satellite. With iridium there is also a cell phone like handover between the satellites.
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Old 13th Mar 2014, 23:09
  #2936 (permalink)  
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For a practical example of "cause and effect" and to offer some professional example to illustrate the effect of both explosive decompression, the resultant hypoxic cabin atmosphere, with measured internal systems damage, and a resultant rapid depletion or remaining flight crew oxygen reserve.

You only have to consider a simple 10 litre oxygen flight crew reserve cylinder at 150 bar pressure exiting through the aircraft skin with the equal and opposite reaction of the cylinder valve exiting up into the passenger cabin causing additional damage and the required decompression leak path.

If in addition the oxygen release were to act with an ignition event, the "fire triangle" of adiabatic heat with a fuel source (metal material etc ) together with the oxygen acting as a fuel you have the basics of an oxygen plasma fire.

The photos below illustrate this with Boeing 747-482 (VH-OJK) Manila Philippines 25 July 2008 just the mechanical explosive damage without a resultant fire of one of the high pressure oxygen reserve cylinders in the forward hold section of the B747

If of interest detail and engineering can be discussed in detail but it does illustrate clearly causation effect.

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Old 13th Mar 2014, 23:12
  #2937 (permalink)  
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So does the monitoring system actually send current status between engine status changes?

The impression I got from earlier posts here was no...that the only time they actually report data is when the engines have significant mode changes and/or there is some parameter that goes beyond a critical threshold.

If my impression is correct, then it again would be consistent with the original WSJ reporting. They know the engines were running and stayed running but don't know anything about their condition or power status, etc. That then gives them the 4-5 hours of continuous flying at some speed, altitude and direction.
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Old 13th Mar 2014, 23:15
  #2938 (permalink)  
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Malaysian Airlines MH370 contact lost

Thanks to all contributing in a meaningful way to this incredible situation!

It would seem to me inconceivable, after 911, with all the money thrown at trying to mitigate risks etc, that NRO/NSA etc don't have programmes to monitor aircraft movements around the world (and I don't mean through fr23!) - they mandated secure cockpit doors against threats of hijacking but didn't have policies on place to know the whereabouts of an aircraft with it's comms switched off?

I suspect we are now in a phase of the US and others quietly leaking/pushing the Malaysians and others into finding this thing with hints , clues etc as they replay and analyse their satellite swoops (hint the indications today). Completely agree that the likes of china and the us won't be in a rush to reveal their abilities but you get to a point that this starts looking so bad it's unreal!

If this plane did somehow land all in tact what in earth could be the point? To fly it somewhere into something? In which case you could just do that in the first plane on a scheduled route.

If the plane was intended to crash, why turn off comms? Surely a terrorist attack is only "effective" if it's publicised. Or is this the ultimate riddle to show how things aren't in control?

Is this a hijacking gone wrong? They turned off stuff then the pilots created hypoxia to trh and incapacitate the jackers, but then crash into the sea (North) 4 hours later?

First change that will happen after this calms down: live, "tamper proof" blackbox feedback. And I suspect those passport databases will be getting checked a bit more too (even if in his case they they turn out to be irrelevant)
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Old 13th Mar 2014, 23:21
  #2939 (permalink)  
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What system are other non essential transmitting systems powered off (radalt etc) Guessing not the emergency and battery busses.... If your engines are running, your idg's obviously have to be running. Acars isn't the only way of determining engines on/off status I suspect.

Last edited by VinRouge; 13th Mar 2014 at 23:49.
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Old 13th Mar 2014, 23:23
  #2940 (permalink)  
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How is the engine data transmitted?

Does the Engine send data via one of the ARINC buses to a RR decoder/transmitter device in the bay and then to an existing antenna for onward dissemination?
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