Malaysian Airlines MH370 contact lost

[Speed of Sound]

For those that mentioned possible SLF cell phone contacts....

That is unlikely.

Cell tower antennae are usually tuned to have optimal performance in 120 degree arc by 60 degree or less elevation. Depending on the frequency and a ton of other factors, practical range is 2 or 3 miles at best (that goes for SMS as well). On an airplane that means something like 10k feet since slant range will be approaching 3 miles, but usually much less because of being outside of antenna cone and an aluminum airframe does a wonderful job of attenuating signals.

Agreed, but I wasn't talking about attempts to connect at 10,000 feet, I was talking about practically every passenger in the last minutes and seconds of the flight desperately trying to speak to or text their loved ones.

If this was over land and anywhere near a mobile network then there is a strong possibility that at least one cell somewhere would have responded.

[b00bsmith]

tip of northern arc = kunming

has anyone mentioned on here yet that the tip of the northern sat arc (or "corridor") happens to be really close to kunming, where fundamentalist separatists/extremists attacked a railway station recently?

[JanetFlight]

Well, if the choosen option was indeed the Northern Arc, we could have here a big obstacle, "greater" if it was flying lower, no radar and under the cover of night simply called "HIMALAYAS", just my 2 cents...your opinions?

[overthewing]

@OldObern

I'm afraid I'm struggling a bit to understand what you mean - can you clarify? When you say that

next ping would show the northern arc in a more southerly location cutting through that point

do you mean that the plane's position would have been on the 50-degree arc rather than the 40-degree?

[fireflybob]

Much mention about one of the pilots hijacking the a/c but what about any member of the crew? Who were the staff passengers - any aircrew amongst them?

[JRBarrett]

Originally Posted by mixture

Utter nonsense. Have you ever tried to use a satellite phone inside of a vehicle ? I have, and you can hardly establish a viable network connection, let alone make a phone call unless you have an external antenna connection, which, lets face it, they are very very very unlikely to have had on a 777 !

IF this incident was a carefully planned and executed hijacking, and IF the hijackers aboard the aircraft were coordinating with accomplices at some destination as yet unknown, there is no reason why they would have to use Inmarsat or Iridium or any other type of satellite network to communicate with their confederates.

The 777 is equipped with at least two powerful HF radio tranceivers, capable of operating on any frequency between 2 and 30 MHz. HF employs simple point-to-point communication directly from transmitter to receiver, and does not require any external network whatsoever. There is no digital data encoded in the signal that could identify the source of the transmission - it is simple single sideband amplitude modulation - a technology that has been in use for decades.

Though an airliner's HF radios are normally used to communicate with ATC facilities on specific frequencies in assigned band segments used for aeronautical communications, there is absolutely nothing to prevent the HF from being tuned to a discrete pre-arranged frequency somewhere else in the 2-30 MHz spectrum - such transmissions are unlikely to be monitored or intercepted in real time, and even if they were, localizing the exact position of the transmissions is quite difficult, due to the nature of ionospheric radio propagation that makes long-distance communication possible at HF frequencies.

Assuming it was indeed a coordinated hijacking, with the aircraft destined for a secret landing at some unknown location, the people awaiting the arrival on the ground would need nothing more than a battery-powered HF transceiver, and a simple long-wire antenna to communicate directly with the aircraft, even if it was still hundreds or thousands of miles away.

As a licensed amateur radio operator, I have done this many times while backpacking in remote areas - communicating with other amateurs around the world, using extremely simple and portable equipment.

[Communicator]

Diego Garcia Radar Range

For reference - JORN in Australia publicly admits to 1,000 - 3,000 km for their OTHR system. Range would tend to be longer during the night and around dawn, but HF propagation is hard to predict.

Australia's Jindalee Operational Radar Network (JORN) comprises three Over-The-Horizon Radar (OTHR) systems and forms part of a layered surveillance network providing coverage of Australia's northern approaches.

JORN provides wide area surveillance of Australia's northern approaches at ranges of 1000 to 3000 km from the radar sites, and is used to conduct air and maritime surveillance in support of Australia's national surveillance effort.

JORN

[BWV 988]

Northern route

@ETOPS

SIA68 intersects with the last Northern radar ping at UTC 00:11 around Ashgabat. Probably others have had the same thought...

[jeanlyon]

You are right, as many years ago when I was first flying, I used to very occasionally ask the flight deck if I could use the HF radio to call my husband, as he was a ham. Highly illegal from an Amateur Radio point of view. I recall I was over the South Atlantic at the time heading for Rio. We had a specified time for the call :-)

[SpannerInTheWerks]

I hate to break this to you Spanner, but the whole world does not run around with CAP413 in their flight bags, white gloves on, saying tootle pip, off we go

No they don't use those phrases either!

Not quite the point of my Post.

In the whole of my flying career I've never heard 'roger that' being used by a line pilot. Maybe things have changed in the past few years, but not in my experience?! I think the airline training Captains might have a wry smile and then correct the phraseology used.

[ZOOKER]

With reference to the unusual RTF phraseology,
Presumably the authorities have listened to all the messages/acknowledgements from that night's MH370, therefore it should not be hard to determine whether the final transmissions were made by either of the two men who were rostered to fly the a/c.
ATC tapes are kept for a few weeks before being overwritten, so it would not be hard to find other recordings of flights where either of the crew were doing the RTF and, if necessary, subject those tapes to voice-spectral analysis..

[Cameronian]

If there were anywhere in the world where OTHR would be justifiable it might be on Diego Garcia. The radar, though, was primarily raised by Unixman. My first interest was in the context of the Iranian "kidnapped" story. The dots seemed to join up once more when the flavour of the discussions here and in the press was of the possible hijacking by the Iranians on board with the stolen passports because the suggested itinerary of at least one of them was to AMS - I doubt the passports would have made the grade there so perhaps his true intentions were different, I wondered. Perhaps Diego Garcia was a target as it has surely played its part in the tensions surrounding Iran and its neighbours over recent years. Building castles in the sky isn't my normal activity though, so interest was not regenerated until reading about the reports of the USS Kidd whose orders seemed to come from a different hymn sheet.

Then where once the FO was suspected now it's the Captain's turn. I wonder who controls the smoke and mirrors. Perhaps we'll never know for sure.

[MountainBear]

define ping

The term "ping" doesn't refer to a particular mode of transmission but a particular type of transmission. That is, a ping refers to the content of the data packet. A ping is either some version of an ACK or a "keep alive" message.

Typically one node broadcasts a message to another node. The node receiving node either returns an ACK (acknowledgement) or a keep alive. Which it returns depends on design specifications. It is something said that when this roundtrip has been successfully completed it is called a "handshake". However, a handshake contains more data than ping because a handshake contains data regarding the network protocol


STEP A: PING

Node A: Are you there?
Nobe B: Yes, I'm here.

STEP B: HANDSHAKE

Node A: Communicate using protocol X?
Nobe B: Yes, let's do that.

STEP C: Normal data transmission

Thus a ping exists only to determine whether there is a physical connection between Node A and Node B. A handshake determines whether there is an acceptable software connection between the two. Pinging a device on a network is the most rudimentary form of communication between two devices.

[dmba]

tip of northern arc = kunming
has anyone mentioned on here yet that the tip of the northern sat arc (or "corridor") happens to be really close to kunming, where fundamentalist separatists/extremists attacked a railway station recently?

The idea that it landed there was rumoured at the very start but quickly dismissed by Malaysian authorities.

[toffeez]

The Malaysian authorities will have red stuff on their hands if it turns out one of the pilots was being hounded by the judiciary.

I have no inside information, but it's not easy for a Malay to be honest about his religious beliefs or lack of them. Nor is it easy to be an 'anti-corruption campaigner'. Can upset some people.

This to be taken with a large pinch of salt and it's not my opinion, only based on what I see on the web.

[techgeek]

Sat link and "pings"

It has been reported that last sat contact was 8:11AM MYT (00:11 UTC) and loss of SSR occurred at ~01:21AM MYT (17:21 UTC). That is an elapsed time of just under 7 hours. If there was an hourly data link connection request (ISO-8208 CALL REQUEST) aka "ping" sent from AES (aircraft) to GES (ground) via satellite there should be a minimum of 6 maps like the one we have seen, each showing the a/c position at a different angle from the satellite (unless it was flying along the arc which is highly unlikely). By comparing the arc of probability of each hourly sat comm one should be able to determine if the a/c was moving NW or SW.

With respect to a fix from 2 sats there is reason to think the a/c flew W from the point of LOC so it could have flown out of range of the POR satellite before the next hourly ping. This may be reading too much into the little info about the sat coms but if the data link requests are truly timed hourly then one can reason backward from last sat contact at +11 to the last sat contact prior to LOC occurring at 17:11 UTC. That gives the a/c 50 minutes to fly westward and out of POR range.

Please disprove this line of reasoning...

[Pontius Navigator]

Originally Posted by SpannerInTheWerks

No, I thought it was the 'roger that' expression.

Okay for the movies, but not to be seen in CAP413.

Sorry SITW, if it started in movies it escaped into real life about 20 years ago. My daughter was operating with US Troops who used that phrase and said how it creased her up.

[aviator1970]

ECMS

possible to assume that comn/pings could be because of data being sent to ECMS(eng condition monitoring system)?.... incase the VHF sets are turned off... default setting would be to transmit data on satcom... no permissions are sought.... any thoughts? this would happen irrespective whether Malaysian had contracted for ECMS or not.... food for thought...

[jugofpropwash]

How sure are they that the aircraft was actually in the air when that last ping was received? Could it have landed sometime earlier and just been sitting on the ground somewhere idling? If whoever was flying knew about the pinging, could they have intentionally used it to "trick" searchers into thinking the plane had flown further than it actually had?

[Emma Voberry]

Thread for non-professionals

A thread has opened for non-professionals to discuss flight MH370:Spectators Balcony (Spotters Corner) - PPRuNe Forums