. Radar

adar is a system that uses radio waves to detect and locate objects and movement. It has become a vital tool for safety and other purposes in aviation and spaceflight.

Air traffic control systems use radar to monitor aircraft movements and guide pilots safely. They use two types of radar. Primary radar locates an air­craft. Secondary radar transmits a signal that is received by a transponder (trans­mitter responder) in the plane. The transponder responds by sending back information about the aircraft, such as its call sign and current altitude.

Airliners and other aircraft are equipped with their own weather radar. The nose of an airliner contains a small
radar antenna that scans the sky ahead of the aircraft and detects storms. Then the crew can change course as needed.