A military plane with 38 passengers on board has gone missing on its way to Antarctica, after losing radio contact with Chile’s air force on Monday evening.

In a world of GPRS networks and sophisticated air traffic control systems, how can a plane disappear like this?

Typically, the first indication that a plane has gone missing will be when it vanishes from the radar, or fails to communicate with air traffic control. How soon after its actual disappearance this might be depends on where it is flying.

On a busy flight path, a disappearance might be spotted in moments. On other routes, it might take 10 to 15 minutes for it to be noticed. When a plane is flying over water it must make regular contact with air traffic controllers on the ground.

As soon as it drops off the radar, the first thing the air traffic controller will do is contact the next radar facility on the plane’s flight path, and then others in the area, to see if they can detect it. If not, they will notify the destination airport where the plane is heading to – as well as all other radar facilities.

There are international search protocols which become effective once the disappearance has been announced – everyone is obliged to start looking for the plane. The military forces in most countries will be informed, so they can lend assistance.