Missing Aircraft and Black box

roker

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One thing that I cannot understand, is why the black box sinks to the bottom and is not made to float ?
 
I suppose it'd have to disconnect itself from the aircraft.... Either that or be able to keep the whole plane afloat or certainly the part attached to the box...
 
I sure hope this thread doesn't turn into another debate about conspiracies surrounding the fate about the missing aircraft. A few things I have noticed with all the coverage is
A. How easy it is to be able to board a plane with a stolen passport and I was astonished to hear that Interpol have 40m stolen and lost passports on their database:eek:
B. Very interesting to note all the amazing satellites China USA and Australia have.
C. How in this technological age can a massive 200 ton jumbo completely disappear without a signal or a blip when people who lose their tiny smart phone can go on a computer and trace them within feet of their location. It truly is mind boggling.
 
C. Disconnect your smartphone from the network and then fly it several thousand miles to the world's remotest reaches. It's still a big place out there.

One thing that I cannot understand, is why the black box sinks to the bottom and is not made to float ?

The black box is designed to withstand massive g-forces and a raging inferno. It's built like an armoured safe, so would be difficult to have it float unless attached to something else big and bulky from which it could become detached or could itself be destroyed in a crash.

But suppose the black box could float -- would it be much use? Vanishingly few planes crash in deep water, mainly because very few accidents occur during the cruising portion of a flight. And even fewer have such a vague last known location as MH370 -- it probably took a concerted and deliberate effort to do that. Suppose the plane crashed in the southern Indian ocean and the black box floated away. It's a relatively tiny device which would quite likely wash up on the shores of Antarctica, never to be found. Whereas if the black box stays with the plane, at least if you eventually locate the wreckage you know the black box is in the vicinity -- it's usually in the empennage / tail section of the plane to increase its likelihood of survival. Plus, the data from the black box (a.k.a flight data recorder) and the wreckage together are often complementary and corroborating sources of information as to what brought the plane down.
 
It's a relatively tiny device which would quite likely wash up on the shores of Antarctica, never to be found

It has an electronic beacon on it
 
It's a relatively tiny device which would quite likely wash up on the shores of Antarctica, never to be found

It has an electronic beacon on it
It only emits a signal for 30 days - they're running out of time...
 
It has just been announced that missing airliner MH370 crashed into the Southern Indian Ocean killing all on board. Our thoughts and prayers go out to the relatives and friends of the lost, how awfully sad it is for them right now.

http://news.sky.com/
 
Sure the announcement, such as it is, doesnt tell anyone anything they didnt already know. I dont think it is that definitive as yet - I saw a screen grab of the text message that said "we can only assume..........".

Maybe they have definite proof but dunno why they wouldnt come out and say it if they have it.
 
It's a relatively tiny device which would quite likely wash up on the shores of Antarctica, never to be found

It has an electronic beacon on it

It has a sonar beacon on it, designed specifically for underwater detection. The sounds from it don't travel in air.
 
Sure the announcement, such as it is, doesnt tell anyone anything they didnt already know. I dont think it is that definitive as yet - I saw a screen grab of the text message that said "we can only assume..........".

Maybe they have definite proof but dunno why they wouldnt come out and say it if they have it.



I would say the evidence is fairly conclusive. However it's complicated and the media "doesn't do complicated", which is why you probably haven't seen it reported. It comes from the Inmarsat satellite that picked up the signals (so-called "pings") from the plane's ACARS system. Although the pings contained no data (because the ACARS data was seemingly intentionally switched off in the first half hour of flight), the following was able to be ascertained up until last week:
  • the last transmitted ping was seven and half hours after the plane took off from Kuala Lumpur;
  • the plane was travelling during that time -- this is known from the timing of the pings, which showed the transmitter was carrying them away from the receiving satellite which is stationary over the equator;
  • it wasn't known which of two directions the plane was travelling, hence the attention on alternate northern and southern corridors that the plane could have travelled;
The latest information is based on a new analysis of the pings which relies on the well-known Doppler effect, the same technique that a traffic cop's radar gun uses to detect the speed of a moving car. Radio signals move up and down in frequency depending on whether the object is moving toward or away from the receiver. The Inmarsat equipment wouldn't normally be used in this way, in fact this technique has never been used before, hence the reason why it has taken this long to obtain. (Frankly, I'm surprised that they even record the raw signal in a form that would allow this to be done, but it seems they do).

This was also probably not a simple job -- the signal is probably frequency or phase modulated, which means there is inherent movement in the received frequency even from a stationary transmitter. Also, the satellite is over 22 thousand miles above the equator and the plane is only travelling a very short distance horizontally over the surface of the earth during a single ping transmission, which means that the change in the plane's distance from the satellite (on which the Doppler calculation relies) is very small. So, even though the cumulative time delay builds up to give the previously known information about the overall flight path (north or south), the directional information from a single ping must be nearly non-existent. Furthermore -- and this is an aspect I don't think has been reported on yet -- the Doppler shift magnitude is not itself direction sensitive. So they presumably used either: 1) the fact that the plane started north of the equator (Kuala Lumpur is at 3° N) and approached the satellite before travelling away again, indicating a north-south trajectory, or 2) the satellite's own small daily drift north and south of the equator was used. They say they will give more details at press briefings tomorrow (Malaysian ministry of transport press conference, afternoon local time on 25th).

I gather that they used historical data from hundreds of flights to look at the signal patterns and compare them to MH370. This would have been a very complicated modelling job and statistical analysis. The Inmarsat results would probably have included a confidence level but I haven't seen that reported. However, in the end they consider the results unambiguous, and Inmarsat had them peer reviewed before releasing them to the Malaysian government. There seems to be little doubt now that the plane flew along the southern track and ended up in the Indian Ocean. The best that can be hoped for now is that debris is positively identified in time to backtrack to a likely crash location -- a calculation fraught with its own difficulties due to chaotic currents in the southern ocean -- while the flight data recorder and cockpit voice recorder sonar beacons are still operational.
 
There seems to be little doubt now that the plane flew along the southern track and ended up in the Indian Ocean.

Exactly, and the degree of confidence that the plane went down in the ocean is down to knowing the fuel remaining at that last contact wasn't nearly enough to get them close to land.
 
One thing that I cannot understand, is why the black box sinks to the bottom and is not made to float ?

I can't understand why they don't make the whole plane of the same material as the black box, so the whole plane becomes indestructible.
 
They aren't indestructible RainyDay, but they are robust. They have a few layers to them and more solid innards than you would like in a plane! They are also armoured with steel plate which would make for a rather heavy and expensive plane and are placed in the tail to provide further protection ( as impacts almost always happen to the front of the plane first you could think of the whole fuselage as a crumple zone for the flight data recorder and the cockpit voice recorder). Basically you wouldn't want to fly inside one but you wouldn't want to fly without one either.
 
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