In a vague hand-wavey conspiracy-related way I thought this story was interesting too:

”Spy plane causes air traffic chaos, says FAA” (BBC News)

heard an interesting titbit this morning.

Where? I can’t find any reference on the interweb.

I find that hard to believe. Why would any sonar operator think that a 33 Khz signal could be made by the data recorder?

So forever the finger of suspicion will point at the pilots and not possibly the real reason. An onboard fire due to cargo or electrical problem.

I heard it from an industry source but:

http://edition.cnn.com/2014/04/08/world/asia/malaysia-airlines-ping-hunt/

Experts said they were not concerned that the pings were detected at a frequency of 33.331 kHz, instead of the design frequency of 37.5.
“We’re listening a little bit on either side of that (37.5 kHz) because pinger (frequencies) do drift,” Dean said.

Well done hora, you’ve solved it. Now could you let us know where it is as well please.

According to the Australians ‘within a thousand square miles of X’. Where X actually is who knows.

Surely the “pings” follows some kind of a recognisable repeating pattern? (i.e. think of an SOS broadcast in morse code), so even if there are other things at the same frequency it can still be picked out and recognised?

nope, they are fairly crude and just ping at a regular rate.

a bit like echosounders…

Just back to this thread after a long absence. Not looking good, is it? At least with AF447 they found wreckage.

I woke up a couple of weeks ago genuinely sure that the ‘plane had been swallowed up by a giant space ship, same as the crew on Mary Celeste. So I went and Googled Mary Celeste and found a plausible explanation concerning an undersea earthquake and the cargo of ethanol, which got damaged and caused the crew to abandon ship in fear of an explosion. So that’s alright then.

nope, they are fairly crude and just ping at a regular rate.

Well that’s a dumb design! I thought it might even do something clever like encode some kind of aircraft identifier in it.

If it literally just goes “ping” at duration and interval that could easily be mistaken for a echo sounder if the frequency drifts then that is pretty poor.

an even smarter design would be to use a active transponder, that only responds to a ping, that way the battery life would be measured in years not days.

the technology is out there. just not adopted.

use a active transponder

You mean passive. But they’re just, effectively, reflectors so won’t you get even more “noise”. Ideal for finding someone in an avalanche – where you know roughly where they are and the stuff they’re buried in is pretty ‘transparent’ but not a lot of good in the ocean which seems to be littered with crap.

Ideal for finding someone in an avalanche

Except they’re not.

Passive RECCO reflectors are good for finding bodies sometime after an avalanche.

Proper avalanche beacons that actually get people out alive do actively broadcast a ping.

But yes I’m surprised there isn’t a secondary “semi-active” system on a black box that essentially just waits listening for an incoming ping before replying.

Receiving should use a lot less power than transmitting (e.g. a mobile phone battery can last for ages if you don’t make calls)

I think he means active.

The problem with active transponders you have to get a signal to them to activate a response. This may not be possible if the wreckage is shielding them, also in very deep water you would need a very strong signal of a suitable frequency to travel the distance.

After the Air France disaster, an updated beacon has been specified, which operates at something like 10 khz and has a much improved battery life. The lower frequency gives it a much greater range. It still needs full approval and it will be several years before they will start being fitted.

no I mean active. you ping them and they ping back.

What can we learn from whales? I remember reading that scientists think they communicate over huge distances, so what can’t we adopt their method?

I remember reading that scientists think they communicate over huge distances, so what can’t we adopt their method?

low frequency, rechargable batteries, utilising the deep sound channel.

You can’t have a passive transponder.. The whole idea of a transponder is that it sends something out and is therefore active. It can however be active or reactive.

Ah, learning new things. So he means a ‘reactive’ transponder. Presumably this still has to be powered up to ‘listen’ but batteries would last far longer?

A transponder is something that both receives and transmits.

Wiki

Some more interesting info here http://en.wikipedia.org/wiki/Underwater_locator_beacon

The limitations of the current beacons were highlighted after Air France.

Investigating the crash, the BEA recommended that FDR ULBs’ transmission period be increased to 90 days and that “airplanes performing public transport flights over maritime areas to be equipped with an additional ULB capable of transmitting on a frequency (for example between 8.5 kHz and 9.5 kHz) and for a duration adapted to the pre-localisation of wreckage” (i.e. with increased range)

If they had done things a bit quicker there wouldn’t be the current problem.

What can we learn from whales?

They seem to regularly get stuck on beaches though and may (allegedly) get confused by submarine sonar, so whatever system they use isn’t exactly foolproof either.

They do, however, have a 100% air safety record.

They do, however, have a 100% air safety record.

What about the one in the Hitchhikers Guide?

This forum still lacks a like button.

it was fine in the air. it just neglected to miss the ground.

Wasn’t it hijacked by a bowl of petunias?

This forum still lacks a like button.

Feel free:

or

Thread bump…

Anyone watching Horizon on BBC2 now? Currently running through the known timeline, how they worked out the route. I think it’s just about to go into the realms of speculation now…

Interesting programme so far.

Strange thing to ask I know but is anyone sure that the plane actually existed in the first place?

It used to exist

No and arse, been watching the football… Grrrrrrrr

Fascinating programme, made a lot more sense of all the disparate info that was in the media.

Yes fascinating, I really didn’t know so little of the planet was covered by conventional radar 10% !
I sort of assumed these days you couldn’t fly anywhere (unless hush hush military stuff) without being on someones screen, the secondary radar stuff was interesting too.
I get the feeling its never going to be found.

as there was a few Aus’ nationals on board it continues to get coverage here – yesterday saying search will resume in August

http://www.smh.com.au/world/area-where-mh370-most-likely-crashed-has-not-been-searched-20140617-zsakl.html

I think the problem is more that we know exactly how fast it was going, and Heisenberg had something to say about that.

Only 10% radar coverage, what chance do we have of tracking UFO’s!

Fascinating programme, made a lot more sense of all the disparate info that was in the media.

I found it a useful summary but otherwise really frustrating. No attempt to address how or why the transponders were deactivated (electrical failure? Deliberate act? Why is it even possible to turn them off?) so moved on from that crucial issue quickly.

Then spent 20 minutes talking about brilliant 21st century technologies that will make vanishing aircraft a thing of the past. Unless of course they are deactivated, by electrical failure or deliberate act…

did i miss something on the Horizon program because when they said it turned back around after the outer marker, then went back across land and slightly north then turned around out to the sea,
all that bit over the land, it *WAS* covered by primary and secondary radar (transponder off for the secondary radar to pick it up though), from the overlay shown in the program.

so why did it not get “seen” by them?

Why is it even possible to turn them off?

Because very occasionally they return incorrect or garbled data – since the same info is used for TCAS it makes sense to be able to switch them off if necessary.

since the same info is used for TCAS it makes sense to be able to switch them off if necessary.

In light of this incident maybe it might make more sense if they couldn’t switch it off, but the traffic control systems could flag their data as dodgy/corrupt?

did i miss something on the Horizon program because when they said it turned back around after the outer marker, then went back across land and slightly north then turned around out to the sea,
all that bit over the land, it *WAS* covered by primary and secondary radar (transponder off for the secondary radar to pick it up though), from the overlay shown in the program.

so why did it not get “seen” by them?

Yep – You missed something.

The Inmarsat guy mentioned that the top secret information given to them by the Malaysians was the primary radar data showing the plane flying back across Malaysia. This was the missing peice in the jigsaw that allowed then to get the flight path from the satelite pings.

The program was very careful to avoid fanciful speculation but reading between the lines they were saying the evendence suggests the following course of events.

1. Something/one disabled the transponder. Could be malicious, could be a very specific fault with the plane
2. The plane turns back. Again this could be malicious or it could be the pilots trying to recover from a fault.
3. Some time later the plane makes another turn towards the Andaman Sea. Again this could be malicious or maybe the pilots had been killed by oxygen starvation but someone with a crew oxygen supply had finally gained access to the cockpit and was attempting to control the plane
4. Another turn is made before primary radar contact is lost. Again this could be a hijacker or it could be the person trying to control the plane.
5. The hourly Inmarsat pings track the plane across the Indian ocean. It’s not just the final ping. They know an arc where the plane could be every hour which enables them to get a fairly accurate flight path.
6. The final ping is different. 8 mins after the final hourly ping the system starts to boot up as it would before take off. The speculation is that this is caused by the plane running out of fuel but then as it banks some fuel sloshes about in the tanks giving a chance for the engines to restart.
7. Therefore there is a high chance the plane will be within a short distance of the location of the “8 min” ping and Inmarsat have been able to pinpoint the location of that ping to a fairly small area.

They search teams haven’t been searching in this area!

I think the conclusion was that unless we find the flight recorders that is about all we will ever know.