The Joint Direct Attack Munition (JDAM) is a tail kit which converts free fall unguided bombs into precision-guided weapons. The tail section contains a GPS/INS guidance system that guides the JDAM bomb through the selected target.
The JDAM bombs can be released in day/night and adverse weather at up to 15 miles away from the selected target. The Pentagon claims that JDAM bomb accuracy is about 13 meters CEP (Circular Error Probable), but according to Boeing sources JDAM accuracy is 9.6 meters CEP. Without the GPS guidance system using only the INS guidance system JDAM accuracy is 30 meters. The advanced capabilities of these smart bombs make possible to attack multiple targets simultaneously as it has been demonstrated during operational representative tests carried out by a B-2 Spirit dropping 16 JDAMs against several targets in a single mission.
The JDAM bombs will be available for all the fighting aircraft of the US inventory (B-1B, B-2A, B-52H, F-16C/D, F/A-18C/D, F/A-18E/F, F-15E, F/A-22, F-35, A-10A, S-3, F-117, AV-8B, and F-14A/B/D) as well as aircraft in development and foreign aircraft.
The GBU-38 is a 500-pound (250 kilograms) class bomb designed to provide increased number of bombs, multiple target attack capability and reduced collateral damage likelihood to current and planned attack aircraft. For example, a single B-2 stealth bomber will be able to carry up to 80 GBU-38 bombs. The weapon is composed by the 500 pounds MK-82 free fall dumb bomb.
JDAMs were used in combat for the first time during operation Allied Force in 1999. The GBU-38 bomb was dropped in combat, for the first time, in the third quarter of 2004 during a combat mission at night in Iraq. The mission was conducted by two F-16C Fighting Falcons, which successfully dropped two GBU-38s on a target in central Iraq. Each aircraft released one GBU-38 on the target-building where a terrorist meeting was happening. The US Navy dropped its first GBU-38 through an F/A-18 from VFA 34 aboard USS John F. Kennedy (CV 67) in Iraq on October 29, 2004.
Boeing delivered the 100,000th JDAM tail kit on December 2, 2004, to the US military since production started in 1998. Initial production was 900 tail kits per month, but as of December 2004 and following 9/11 terrorist attacks, tail kit production boosted and stands at 3,000 units per month. These tail kits provide precision strike capability to Mk 80 series bombs through GPS-aided navigation. To date, the US Air Force has received more than 50,000 JDAMs, the US Navy roughly 37,000 units, and the remaining tail kits (10,000?) were produced for international customers.
Boeing was awarded JDAM Lot 9 production contract valued at $609 million on 31-March-2005. The US Air Force Lot 9 contract called for 30,072 JDAM tail kits with 60 percent of those kits to be produced for 500-pound bombs (GBU-38). As of March 2005, Boeing has produced more than 112,000 JDAM tail kits.
In October 2005 Australia's Department of Defense awarded Boeing a contract to provide 500-2000 pounds JDAM weapon systems in support of the Royal Australian Air Force's F/A-18 combat aircraft fleet.
In early March 2006 Boeing was awarded JDAM Lot 10 production contract for 10,000 JDAM tail kits for 500-, 1,000-, and 2,000-pound bombs owned by the US Air Force and the US Navy. This new contract was valued at $240 million and tail kits deliveries were slated for completion by February 2008.
Specifications
Weights:
Max Weight 230 kg (507 lb)
Performance:
Ceiling 13,700 m (44,948 ft) , CEP 9.6 m (31 ft) , Max Range 24,000 m (78,740 ft)
Australia
Saudi Arabia / 550 
South Korea
United States of America / 5,800 