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Comment by markbnj | Hacker News Reader

I was thinking yesterday that there are not _that_ many jets the size of the 777 in the world, and the location of most of them can probably be detected by U.S. military satellites. If that satellite data were correlated with data from the airlines on the location of their planes, some much smaller set should emerge that consists of planes whose location does not have an official explanation.

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Commercial satellites are ok for seeing planes for that matter. It's knowing where and when to look that's important. I don't think that even the US military constantly monitors vast tracts of empty ocean on the off chance that a plane might crash there.

https://maps.google.com/maps?q=35%C2%B003%E2%80%B234%E2%80%B...

For instance, these two maps are pretty similar in scale (I couldn't make Maps do the exact same scale though)

https://maps.google.com/?ll=44.527843,13.227539&spn=14.14170...

https://maps.google.com/?ll=-32.509762,80.991211&spn=16.6984...

That's a "whole lot of nothin'".

I don't think that even the US military constantly monitors vast tracts of empty ocean on the off chance that a plane might crash there.

https://en.wikipedia.org/wiki/SOSUS

Lines (chains, as per your article) have a "lot less area" than rectangles do, though. In other words, it's way, way easier to answer "what has crossed this line, at what time?" than "is there a needle in this haystack as large as Europe?", especially when the rectangle in question is basically of zero interest 99.9999% of the time, and you're tying up resources that could be pointed at China, North Korea, Russia, Iran, San Marino or other more 'interesting' places.

Furthermore, as your article mentions, they decommissioned some of that because it was too expensive and didn't serve much purpose with the end of the cold war. Even those guys' budgets are not unlimited.

Pardon my ignorance, but why is San Marino in that list?

You never know what the Sammarinesi are plotting up there on that rock! Mostly just to see if anyone was paying attention :-)

Yeah, I was thinking specifically of the case where the plane is still intact and on the ground somewhere. If it has crashed into the sea this technique wouldn't be useful. And it could also be foiled by hiding the plane, which would be a large but not impossible task.

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