Friday, March 26, 2010


Air traffic detection and ranging

We all know that air traffic controllers use radar to track airplanes.

“Radar” is, as many of us do not know, an acronym for RAdio Detection And Ranging. A radar system uses reflected radio waves to determine an object’s location and distance, relative to the radar system.

Quick quiz: Name something else that gives us location information, these days.

Exactly: the Global Positioning System, GPS.

Of course, GPS gives an object’s position in absolute terms, but that’s fine. As long as we know the GPS coordinates of everything we’re concerned about, we’re OK. Apart from that, GPS gives better resolution and accuracy than radar does.

So, why shouldn’t air traffic control use GPS instead of radar?

Why not, indeed:

The Senate voted Monday to approve a bill that would speed the modernization of the nation’s antiquated air traffic control system by replacing radar with GPS technology.

The only catch is that GPS is a passive system, requiring the plane to get its location and send it to the controllers (as is currently done with altitude in the radar system). If there’s a malfunction in the plane, and the on-board GPS systems aren’t working, the controllers will need a backup system on their end. So I presume that the old radar won’t go away completely. (Of course, there’ll certainly be several parallel GPS systems on the planes, so it would take a severe failure to take them all out.)

1 comment:

Ray said...

It's all very well the US senate voting on this... but surely this is something that requires world-wide cooperation and coordination? Or, perhaps more likely, the rest of the world decided to do this ten years ago, and the US is just now catching up.