GPS has changed the way air support is delivered. The most important change, and not widely known outside the military, is the elimination of the tedious, and often inaccurate process whereby a guy on the ground talks in a bomber pilot overhead, so that an enemy position can be bombed. This has always been a tricky operation, and often ended with friendly troops hit instead. GPS has changed all this since the 1991 Gulf War. Pilots (of bombers and gunships) and troops on the ground both have GPS. Getting the pilot over the target is a lot easier. And a lot of laser guided bombs are still used, which require the bomber to come in close to the friendly troops to drop the bomb. Smart bombs can only glide so far, and if the bomber isn't close enough, the bomb will hit the ground short of the target. A-10s, AC-130 gunships and attack helicopters also need to find friendly troops quickly and GPS makes this a lot easier. Initially, ground air controllers would verbally tell pilots their GPS coordinates, and this is sometimes still done. But increasingly, people on the ground have GPS wired into their radio equipment and can transmit the GPS coordinates to pilots automatically, as well as the coordinates of targets. All this has made air attacks in support of ground troops happen a lot faster, and with less risk of friendly fire.