MiniMatt

Me & the missus were trying to figure this out last night - how do planes know where they are? We figured it's a combination of old fashioned navigation (compass tells me I'm flying in this direction, speedo says we're going at this speed, last known point we passed was X, therefore we're currently at Y) and modern GPS (figure there's enough satelites up there that the plane can spot at least 3 from just about anywhere in the world?).

If all that's the case then wouldn't the automated message thingy that got sent out also include a "oh, by the way, this is where I reckon I am - send us a boat if you don't hear from us in a couple minutes"? Naturally the plane's figuring of where it might be in the world is liable to glitches, incorrect programming and god knows what else, and naturally in the middle of the ocean there's unlikely to be any radar stations that can verify the data.

Just struck us as odd that it's possible to pretty much lose a plane in this day and age (lose as in not know where it is). That automated message thingy - presumably that's radio - is it on a band monitored by traffic controls the world over or just the airline or the manufacturer? Have I missed something, would have thought that if that included a "this is where I reckon I am" location then (assuming that's correct) a couple of likely impact points can be determined pretty quickly (ie. if it went pop in mid air then it's likely to fall pretty quick and land within a mile radius of X, or if they managed a controlled descent they may have glided down to a hopefully smoothish landing within a couple mile radius of Y). At the moment it sounds like they're scouring hundreds of square miles of ocean?

Dunno, I'm no good at armchair aviation.