GBU-31 JDAMGBU 31 JDAM desk model. The GBU 31 JDAM Bomb was a guided weapon for air to surface functionality. The term JDAM stands for Joint Direct Attach Munitions, which work as a guiding kit to transform unguided bombs (also called Dumb Bombs) to smart munitions that can operate on all weather conditions. Bombs that are equipped with the JDAM technology are directed by an integrated system coupled with a GPS receiver. This feature gives the system up to 15