Joint Direct Attack Munition

Joint Direct Attack Munition (JDAM)
GBU-31: A Mk 84 bomb fitted with JDAM kit
Type	Fixed target, precision strike, moving vehicle
Place of origin	United States of America
Service history
In service	1997–present
Used by	See operators
Production history
Unit cost	Approx. US$25,000 (Depends on acquisition lot. Foreign sales have considerably higher prices.)
Variants	See variants
Specifications
Length	9.9–12.75 feet (3.02–3.89 m)
Maximum firing range	Up to 15 nautical miles (28 km)
Wingspan	19.6 to 25 inches (500 to 640 mm)
Accuracy	Specified 13 meters; Realized around 7 meters

The Joint Direct Attack Munition (JDAM) is a guidance kit that converts unguided bombs, or "dumb bombs", into all-weather "smart" munitions. JDAM-equipped bombs are guided by an integrated inertial guidance system coupled to a Global Positioning System (GPS) receiver, giving them a published range of up to 15 nautical miles (28 km). JDAM-equipped bombs range from 500 pounds (227 kg) to 2,000 pounds (907 kg). When installed on a bomb, the JDAM kit is given a GBU (Guided Bomb Unit) nomenclature, superseding the Mark 80 or BLU (Bomb, Live Unit) nomenclature of the bomb to which it is attached.

The JDAM is not a stand-alone weapon; rather it is a "bolt-on" guidance package that converts unguided gravity bombs into Precision-Guided Munitions, or PGMs. The key components of the system consist of a tail section with aerodynamic control surfaces, a (body) strake kit, and a combined inertial guidance system and GPS guidance control unit.

The JDAM was meant to improve upon laser-guided bomb and imaging infrared technology, which can be hindered by bad ground and weather conditions. Laser seekers are now being fitted to some JDAMs.

From 1998 to August 20, 2013, Boeing delivered 250,000 JDAM kits, producing over 40 guidance kits per day.

The U.S. Air Force's bombing campaign during the Persian Gulf War's Operation Desert Storm was less effective than initially reported, due in part to the lack of a precision guidance package for its bombs that would function regardless of environmental factors. Laser guidance packages on bombs proved exceptionally accurate in clear conditions, but with significant amounts of airborne dust, smoke, fog, or cloud cover, the guidance packages had difficulty maintaining "lock" on the laser designation. Research, development, testing and evaluation (RDT&E) of an "adverse weather precision guided munition" began in 1992. Several proposals were considered, including a radical concept that used GPS. At the time, there were few GPS satellites and the idea of using satellite navigation for real-time weapon guidance was untested and controversial. To identify the technical risk associated with an INS/GPS guided weapon, the Air Force created in early 1992 a rapid-response High Gear program called the “JDAM Operational Concept Demonstration” (OCD) at Eglin Air Force Base. Honeywell, Interstate Electronics Corporation, Sverdrup Technology, and McDonnell Douglas were hired to help the USAF 46th Test Wing demonstrate the feasibility of a GPS weapon within one year. The OCD program fitted a GBU-15 guided bomb with an INS/GPS guidance kit and on 10 February 1993, dropped the first INS/GPS weapon from an F-16 on a target 88,000 feet (27 km) downrange. Five more tests were run in various weather conditions, altitudes, and ranges. The OCD program demonstrated an 11-meter Circular Error Probable (CEP).