Now the chokepoint is, predictably, the airfield at Port au Prince, which lost its air traffic control equipment.
The signal, standard on all aircraft, set off a series of alarms at air traffic control towers in the area.
Or note the air traffic control system that helps their plane get in safe.
The flight path remained close to the Indonesian archipelago, well within what is the normal reach of air traffic control radar.
a ground-based system for controlling and monitoring air traffic within a designated area