There has been a number of posts made recently that mention ELT (Emergency Locator Transmitters). For the benefit of those who are not familiar with aircraft electronics, there are two main types of ELTs: those which are intended for use on land, and those intended for use on (or in) water.
Virtually all civil aircraft are fitted with a fixed ELT that is located towards the aft end of the fuselage (this to minimize damage in the event of a crash). This ELT is connected to a small antenna on the outside of the aircraft. The fixed ELT is typically activated automatically by G force, although it is usually possible to turn it on manually using a switch in the flight compartment. This type of fixed ELT is of little or no value if the aircraft lands (or crashes) in water and then sinks, because the radio signal emitted is attenuated by the water above it.
The second type of ELT is one that is designed for use if the aircraft lands (or crashes) on water. It transmits the same type of signal as the fixed ELT described above, but it is normally stowed in a quick-release bracket within the cabin, the idea being that it will be manually removed from its mount and deployed by the crew in the event of ditching. This type of ELT activates automatically when it comes in contact with water, and like the other type, can also be activated manually. But, if it is not removed from the mounting bracket and deployed manually after a ditching, the signal it emits will likely not be detected. Same as with the fixed ELT, if this maritime ELT sinks with the aircraft, the radio signal that it emits will be attenuated by the water above it.
Below is a photo showing a marine-type ELT as installed in an Air Canada aircraft. It is stowed in one of the overhead baggage bins, close to the forward left cabin door.
Here is a link to a document published by Honeywell (a manufacturer of ELTs) that provides additional information about the various types of ELTs available. Honeywell 406 MHz ELTs
Maritime ELT, as installed in an Air Canada aircraft
phil, I get your drift, and I think we are drifting off topic as well.
The piece of the puzzle that is making me scratch my head: if the plane flies for about an hour in directions not part of their original route to PEK, why no comms? Pilot incapacitation or equipment failure, or both? More puzzle pieces needed to bring this picture into focus.
"MARANG: Eight villagers here lodged police reports today claiming that they had heard a loud noise last Saturday coming from the direction of Pulau Kapas and believed it was linked to the disappearance of a Malaysia Airlines (MAS) flight on that day."
If you read his theory carefully, he says ' It’s plausible that a fuselage section near the SATCOM antenna adapter failed, disabling satellite based - GPS, ACARS, and ADS-B/C - communications, and leading to a slow decompression that left all occupants unconscious.'
ADS-B/C = transponder, I think?
The Transponder(ATC) antennas are separate from SATCOM antennas and would not be effected.
Last edited by Lost in Saigon; 11th Mar 2014 at 15:25.
Reason: I wasn't sure of exact locations of antennas
This reminds me of the initial AF447 thread. Some of the same members also.
Theories we can (almost) 100% eliminate:
All very logical, except that you are making assumptions about the absence of RT/Transponder/ACARS information which may not be true.
We can't think of any likely scenarios where an a/c disappearance can happen with no comms and no debris near LKP. There are unlikely possibilities of course, but I prefer incompetence over conspiracy. We know the Malaysian authorities have been withholding information. My best guess for this is that they want to find the a/c and keep control of the story to minimize embarrassment.
If there was RT/Transponder/ACARS data which was lost or is being withheld, then perhaps this incident could have a more believable cause, like a flight upset or fault which was inappropriately handled.
I could be wrong, the incident could be a strange hijack or a bizarre failure of multiple systems on the famously reliable T7. But it seems increasingly likely to me that the reason the a/c has not been found is poor communication between the parties.
I really don't see any big conspiracy over this change of SAR mission from the east of to the west of the peninsula. When the flight first 'went missing', it was positioned east of the peninsula heading NNE so naturally the search was concentrated there.
In the meantime the military has said privately to the government 'hold on we are pretty sure we saw something heading west without identification but need too look at our raw primary data to get a better picture' (and check that nothing classified was being revealed!) On the strength of this some assets were diverted west to the Straits with the caveat "We can't say why" presumably because all the information wasn't in yet, and now the military have come back with confirmation that they did track an unidentified aircraft heading west towards the Straits and today that information was made official.
What's the big deal?
What kind of military would be "pretty sure they saw something [the size of a 777] heading west without identification" and just shrug it off for the meantime until they get a chance to go back through their radar data?
It seems quite a big deal to me, due elapsed time and the amount of SAR effort expended in the Gulf of Thailand.
My earlier post was deleted, but the point I tried to make was that the Malaysian Air Force must also know which way it was heading, but havenít said so. To Pulau Perak From their previous position was approx hdg 250. To KUL hdg 140 and 240nm, to PEN 107 and 80nm. Continuing on 250 would put them in the mountains and jungle of Northern Sumatra.
All airforces surveillance worldwide is being done with primary radar. No enemy will switch on their transponder before they attack, so SSR is kind of useless from a military border-watching point of view.
30 years ago, a normal primary radar was able to follow flocks of birds without any problems at all. Todays radar equipment is of course much more refined and exact. Following a B777 is among the easiest tasks ever. Its massive, not supersonic, no jamming, and it oftens flies quite high and straight.
So, either the normal 24/7 radar surveillance in the area was not operational at this time (how embarrasing for all involved countries), or there are quite a few people within the borderwatching units who has known all the time where, exactly, primary radar contact was lost...
"The P-3C and the MH-60 have surface search radar with a range of 5000 to 10,000 feet that can look down and pick up pretty small objects, even non-metallic ones, and down to basketball size," says William Marks, a US Navy commander on the USS Blue Ridge, which is coordinating the US search contribution. "Then the crew will use high zoom cameras to zoom in and check it out. Yesterday, for instance, we found something that looked interesting but it was just a wooden crate."...
MISSING MH370: Loud noise reported, believed linked to missing plane
MARANG: Eight villagers here lodged police reports today claiming that they had heard a loud noise last Saturday coming from the direction of Pulau Kapas and believed it was linked to the disappearance of a Malaysia Airlines (MAS) flight on that day. All of them, from Kampung Pantai Seberang Marang, made the reports at the Marang district police headquarters at about 10.30 am.
One of them, Alias Salleh, 36, said he and seven fellow villagers were seated on a bench about 400 metres from the Marang beach at 1.20 am when they heard the noise, which sounded like the fan of a jet engine.
"The loud and frightening noise came from the north-east of Pulau Kapas and we ran in that direction to find out the cause. We looked around the Rhu Muda beach but did not see anything unusual," said the lorry driver.
Replying to a question, Alias said they lodged the police report so that it would be of help to the authorities who were trying to locate the missing MAS aircraft.
MAS Flight MH370, carrying 227 passengers and 12 crew, went missing en route from Kuala Lumpur to Beijing about an hour after taking off from the KL International Airport at 12.41 am Saturday.
It was flying above the South China Sea off Kelantan at that time. It should have landed in Beijing at 6.30 am but has disappeared without a trace.
Another villager, Mohd Yusri Mohd Yusof, 34, said when he heard the strange noise, he thought a tsunami was about to strike.
"My friends and I heard the ringing noise for about two minutes. I decided to lodge the police report after seeing the media reports on the lost flight," he said
If the Chinese thought the Malaysians where manipulating the story to save national face ( Chinese know this game ) they would be screaming blue murder . They moved 20 odd satellites over the area . Think it really is a mystery to everyone . Fingers crossed tomorrow there is a break through.
There seems to be general perception here that ACARS transmissions are more or less continuous - that is NOT the case.
Each ACARS message cost money - not much - but if an aircraft is sending out continuous messages it adds up really fast. Hence, ACARS is set up to transmit only when specific events occur - e.g. a system or LRU reports a fault. Similarly, engine condition monitoring does not continuously spout out data via ACARS or other downlink. Rather there are engine parameter algorithms that look for certain 'stabilized' events - e.g. stabilized takeoff or cruise conditions. If those specific events are not met, nothing is downlinked.
So, the absence of apparent ACARS messages is not in and of itself unusual. What is potentially of interest is that the lack of ACARS messages would either imply either a lack of systems failures or a sudden failure (or human action) that disabled ACARS.
It seems quite a big deal to me, due elapsed time and the amount of SAR effort expended in the Gulf of Thailand.
Thomas. Please go back to my post that begins "In defense of Malaysian Authorities." (No, I am not Malaysian, but I made a port call in Penang once). With contradictory information to hand, seems prudent to search in both areas that may be where one should start while resolving the contradiction in the data available. (That, and maybe saving some face if, for example, at zero dark thirty in the morning one of the radar operators was ... asleep at his post? Don't know, but that might explain why it took a while to uncover what that radar sight had painted that evening ... I admit I am guessing on that but it fits within three sigma what happens to some people on the graveyard shift).
My earlier post was deleted, but the point I tried to make was that the Malaysian Air Force must also know which way it was heading, but havenít said so.
See above. Not necessarily so until later it became evident what their radar had seen. Add some face saving ... presto, it begins to make some sense.
To Pulau Perak From their previous position was approx hdg 250. To KUL hdg 140 and 240nm, to PEN 107 and 80nm. Continuing on 250 would put them in the mountains and jungle of Northern Sumatra.
What if they were having a hard time maintaining a constant heading? Something, or a number of somethings, were not quite right with this flight. When the radar track info is made public, if it ever is, it will be interesting to see what flight path that aircraft followed once it left the route toward PEK.
None of this seems to make any sense. I think we can put to bed the possibility of terrorism. At least in terms of a large scale organised plot. There have been no claims of responsibility for this event. That tells its own story. Any opportunistic terror group who saw an opportunity to claim responsibility but were subsequently shown to be talking out of their collective asses when the aircraft was found and no foul play was evident would instantly lose any credibility whatsoever and therefore much of their fear factor in the process. Do not think terrorist groups are not aware of this.
If as now appears to be the case the Malaysian military were aware that there was a 777 heading west over the Malay peninsula in the early hours of Saturday morning they presumably did not simply ignore it and do nothing but would have sought authority either to intercept and identify or intercept and force it to land. They could of course have been told to ignore it but that would be a positive decision by a senior officer or a politician. Obviously there are therefore many people who risk losing face and the more senior they are the greater the potential loss of face. Their vested interests will make it progressively harder to "do the right thing", whatever that may be.
The longer the SAR mission lasts the greater the potential humiliation , whatever the real cause was and whatever the outcome for the flight. Perhaps the only way to break the seeming deadlock is for an outside party to produce evidence eg the alleged mayday message received by the US/Royal Thai Navy AFB at U-Tapao?
Having worked in Singapore/Malaysia for nearly 20 years, I don't believe this stuff about the Malaysians 'covering up' what they know for days, just to save face. They're pretty clued up at senior levels (even if performances at press conferences are not very impressive). They're not stupid enough to think that with ships, aircraft and miscellaneous technically expert personnel of sundry countries running around the search area(s), monitoring every bit of equipment they can lay hands on, they would be able to cover up anything really significant for any time. 'Face' is important in this part of the world, but not to such a lunatic extent. Seems much more likely that they've been working with unconfirmed information, and pending confirmation they've been hedging their bets as to search locations. Isn't that what anyone sensible would do? For all we know they have been sharing unconfirmed information with their international collaborators in the search effort.
Similarly with the passports. They didn't release information publicly until they had something solid to release (and until they had spoken in Frankfurt to the mother of that poor chap, not least). Fair enough, it seems to me.
The 777 use Honeywell FMS system, There are several AD on the FMS. United airlines had an incident in a B747 a few years back, the FMS guided the airplane parallel to the Runway basically offset with a mile over the water in SFO.
Honeywell have had numerous problems with the data base, further you fly greater error.