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Comment by te_chris | Hacker News Reader

Edit: the top reply made me realise what has probably happened. Awful :(

Generally the tracking doesn't work so well after the plane has crashed into the ocean.

Saying that you've lost contact with a jet is another way of saying that "it's probably crashed, but we don't have any solid proof yet."

GPS just means the plane knows where it is. The equipment necessary for the plane to inform the airline ops about its location is still vulnerable to all sorts of problems, even with the kind of anal development practices required by FAA and equivalent agencies. Airports usually have have radars that track nearby airspace, but otherwise, I think most planes are tracked by the ADS-B signals that they actively transmit (insecurely).

Does that mean that they pretty much know where the plane is likely to be? I recall from previous accidents that sometimes they can't find the plane very quickly. I don't know much about this subject, but what stops them from locating the plane within just a few hours?

I was wondering the same thing. I'm guessing as much as the media and Hollywood want us to believe that the government / military is tracking everything in the air, in reality that isn't really the case.

Over water or in other remote locations, there is no radar coverage thus there is absolutely no information about the plane location except position reports from the pilot. Airliners have "ping home" systems that regularly send various info (including GPS location) back to the central company servers using satellites. However, the reports frequency varies from 15 to 90+ minutes and even 5 minutes is A LOT for a plane traveling at MACH 0.7. But even if the position reports will be timely and accurate, during the descend (after a catastrophic event onboard), the plane might travel tens of miles from the last reported position. Then, ocean currents can move the pieces even further from the last reported position (as it have happened with Air France plane pieces).

Lastly, ADS-B is not a solution for over the ocean position reports - the radio is not powerful enough to transmit data over the long distance (this is why we need to build so many ground stations in the US to actually use it). Not to mention, that ADS-B is not fully operational even in US.

I think they could look at satellites looking at that region at the time. There are satellites just taking photos and they probably have captured something.

...there really aren't satellites 'just taking photos' of the ocean. You might have a spy satellite taking pictures of a naval exercise. I think you are underestimating a) how vastly big the ocean is, and b) satellite capacity (most intelligence satellites are over land).

71% of the world is ocean. The ocean is vast, and most of it has very little going on. Last month someone washed up having been lost at sea for over a year, having only seen two or three ships (which didn't stop). A few ships in 13 months.

http://www.cbsnews.com/news/jose-salvador-alvarenga-healthy-...

Normally, you are right.

'Lost contact' therefore suggests something very wrong has happened.

GPS position must be calculated on the plane and transmitted off the plane. You can't see how that connection might be interrupted?

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