Using RADAR (see photo and explanation below) air traffic controllers can "see" aircrafts in the sky .
The air traffic controller saw Flight 401 on his radar screen.
He asked them about how things were out there.
The Captain decided to turn around and return to the airport.
Air traffic controller: Eastern, ah 401 how are things comin' along out there? Capt to air traffic controller: Okay, we'd like to turn around and come, come back in (the captain decides that its time to turn around and return to the airport to land) Captain: Clear on left? Co-pilot: Okay Air traffic controller: Eastern 401 turn left heading one eight zero (turn left and head South)
Radar dish at London Heathrow International Airport. Rotating radar dishes like this one beam radio waves into the sky. The same dish then listens to any radio waves that bounce back from aircraft. These "echoes" are electronically analysed and aircraft position and altitude are displayed (as a dot or symbol) on a screen. Using this information, the air traffic controllers guide aircraft to the airport by giving instructions over the radio. Because the controllers can see all the aircraft , they are able to keep them separated from each other to prevent mid air collisions. (Photo copyright freshgasflow.com)
