Ditzy

Question for ye wise people.

At the start, it was theorised that the reason the black box hadn't been found was because it was at the bottom of the sea so no sonar had picked it up yet etc.

Assuming it's sitting safely on the ground/in a hangar somewhere - why is it not able to be traced now?

Black box is different from transponder etc, is it not?

mikewot

ACARS is very useful to airline ops for giving info on the aircraft, like speed, weather, height, position, fuel usage etc. Emirates Ops room in EKHQ on the Airport Road (the building with the massive picture of that womans face) has a huge display tracking every aircraft in their fleet around the world. They can call up statistics for each airframe, each engine etc.
Not all fleets have that but Boeing offer it if you want to pay, so on this flight the ACARS was sending out a 'hello I'm here, talk to me" to Boeing HQ which refused to handshake (hello, nice to hear from you, how are things?) so no data ever got sent. The ACARS system usually uses VHF radio but in some places coverage is no good so it switches to satellite.
What they're chattering about on the satellite is where was the aircraft on the last ping the ACARS sent. You end up with two arcs because the satellite is moving pretty rapidly and relies on the doppler effect to figure out where the signal was, but it could be either side of the satellites track. ELT (Emergency Locator Beacons) use exactly the same principle for the satellite to figure out where the beacon is.

The issue arising from this whole situation is one where we (ATC) are going down the route of cooperative target surveillance. More reliance on the aircraft telling us where it is with it's systems on board and ATC confirming that using Multi Lateration (auto triangulation). Yea olde primary radar with all it's problems is gradually being eroded in the civil world with only the military demanding it. So when you have a non cooperative target it's much more difficult to 'see'.

Pica

Mis-scan

Ditzy

I think I understand your explanations MW, but where I'm losing it there is when they are talking about ACARS being sent by satellite rather than ACARS and which side initiates it etc it's getting very confusing!

Ditzy

But why/how....? Why was anyone photocopying it in the first place? It seems odd in this day and age to be photocopying things and overlaying one image over another and it just happens to be in the same place as the other photo's legs!

all VERY odd.

mikewot

Black box is the Flight Data Recorder (actually they are orange) and records accident data, nothing to do with any flight critical system, like the transponder.
They emit an underwater locater 'noise' for up to 30 days down to 6,000 metres. Hangers tend to be quite dry.

Ditzy

So it only emits a tracer thing if it's under water???

Wow.

Pica

Photocopying CCTV pics to give out to the media (sends people scurrying off in the wrong direction?) maybe they did it in a hurry and ran 2 through one after the other too quickly?
I really don't know but can't imagine anyone would not spot the mistake or be so easily fooled. A simple error me believes!

mikewot

Of course, because on land you tend to pick out a couple of fluorescent oranges boxes in amongst the charred wreckage quite quickly. And they're at the back because it's more resistant to damage when your aircraft ploughs in nose first. Hint for choosing seating there.

OriginalSunshine

would you cause a plane to explode mid air if they said they were carrying radioactive material? you'd want that to disperse would you? or if you managed to shoot it down so it crashed, what would you do then?

anyway - here's another site to plough through: http://www.flyertalk.com/forum/other...-wiki-171.html

Millhouse

If the decision is to blow it up over the Channel where the wind may blow it to dover and hand out some iodine pills to a few immigrants vs. letting it crash in London, then probably.

Eeyore

Over sea or the many very large uninhabited (or very sparsely-inhabited) areas it would have to pass over before it got anywhere near the UK, yes, without hesitation.

Hell, as Millhouse says, the Channel would do as just as well, even if - by some utter miracle - it wasn't detected and intercepted thousands of miles before it got to the UK, which it absolutely would be.

Seriously, it's almost vanishingly unlikely that it's been hijacked with the intention of flying it to London, or any European city. Unless they are terminally stupid the hijackers would be only too well aware they would be picked up on radar before they got anywhere near European airspace, and they can't avoid flying over areas that would allow them to be shot down with minimal to zero risk to anyone on the ground.

The Dean

Apologies if someone has already posted this, but it seems the most rational explanation I have seen so far.................

https://plus.google.com/app/basic/st...rfyiz3vdhbop04

shakh your bootie

It would be plausible if the transmissions from the engines back to RR in Derby had not shown that systems were functional and showed no signs of fire damage hours after the supposed catastrophic failure.

Millhouse

Impossible. A terrorist attack that involved sending decoys to spoof the planes location and all communication signals is much more believable.