Airborne early warning and control (AEW&C) aircraft are some of the most expensive and valuable aircraft in any air force’s inventory (they are also called Airborne Warning and Control Systems or AWACS). While they spy on the enemy, they are not intended to remain unseen unlike true spy planes. These aircraft carry powerful airborne radars to detect ships, other aircraft, missiles, and other targets and threats at great distances. Among other things, they can greatly enhance the capabilities of fighter jets. Here are five AEW&C aircraft to know about around the world.