Air-to-ground weapons system evaluation. US Air Force F-16CJ aircraft releasing a GBU-31 2,000 pound Joint Direct Attack Munition (JDAM) over the Eglin Land Range, USA, during a test mission. The JDAM is a guidance tail kit used to convert conventional unguided general purpose bombs into adverse weather 'smart' munitions that use an inertial navigation system (INS) and global positioning system (GPS) guidance control unit to greatly improve their accuracy in any weather condition. This Air-to-Ground Weapons System Evaluation Program (WSEP), commonly known as Combat Hammer, evaluates both the Squadron's ability to effectively employ the weapon and the weapon's performance in an operational environment.