Joint Direct Attack Munition

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GBU-31: Mk84 bomb fitted with JDAM
GBU-31: Mk84 bomb fitted with JDAM
Joint Direct Attack Munition (JDAM)
Mission: Close air support, interdiction, offensive counterair, suppression of enemy air defense, naval anti-surface warfare, amphibious strike
Length: 9 ft 11 in–12 ft 8 in
(3.0–3.9 m)
Wingspan: 1 ft 7 in–2 ft 1 in
(483–635 mm)
Range: Up to 15 nmi (24 km)

The Joint Direct Attack Munition (JDAM) is a low-cost guidance kit that converts existing unguided gravity bombs, or "dumb bombs", into accurate, all-weather "smart" munitions. JDAM equipped bombs are guided to their target by an integrated inertial guidance system coupled with a Global Positioning System (GPS) receiver for enhanced accuracy, giving them a published range of up to 15 nautical miles from the release point. JDAM is a joint United States Air Force and United States Navy program. It is in service with the U.S. Air Force, U.S. Navy and the U.S. Marine Corps.

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The JDAM is not a stand alone weapon system, rather it is a "bolt-on" upgrade for unguided gravity bombs that is installed in the field by Aviation Ordnancemen. JDAM equipped bombs range in size from 500 lb (225 kg) to 2000 lb (900 kg).[1] The kit is compatible with the entire Mk-80 family of general purpose bombs, as well as the corresponding BLU penetrator warheads. JDAM consists of a tail section with integrated aerodynamic control surfaces, a stabilizing strake kit, and a combined inertial guidance system and GPS guidance control unit. JDAM enables accurate delivery against high priority fixed and relocatable targets from both fighter and bomber aircraft.

Desert Storm highlighted a shortfall in air-to-surface weapon capability. Limited visibility of the ground caused by smoke, fog, dust and cloud cover limited the employment of precision guided munitions. Unguided weapon accuracy was also degraded when delivered from medium and high altitudes. Research and development of an "adverse weather precision guided munition" began in 1992. The first JDAMs were delivered in 1997 with operational testing conducted in 1998 and 1999. More than 450 JDAMs were dropped during testing, recording an unprecedented 95% system reliability while achieving an accuracy of 9.2 - 9.9 meters Circular Error Probable (CEP).[2] JDAM performance has been demonstrated in operationally representative tests including drops through clouds, rain and snow. in early tests, a B-2 Spirit released 16 JDAMs on a single pass against multiple targets in two separate target areas. More recently, on September 10, 2003, a B-2 Spirit bomber successfully released eighty (80) inert 500 pound (230 kg) Mk82 bombs equipped with JDAM kits on a single bomb run, lasting 22 seconds, and with each weapon engaging a separate target.[3] An Air Force spokesman described this accomplishment as "revolutionary."[3]

JDAM and the B-2 made their combat debuts during Operation Allied Force. The B-2s, flying 30-hour, nonstop, round-trip flights from Whiteman Air Force Base, Missouri, delivered more than 650 JDAMs during Allied Force. An article published in a military acquisition journal in 2002 cites that "During Operation Allied Force, March 29 through June 9, 1999, B-2s launched 651 JDAMs with 96% reliability and hit 87% of intended targets..."[4] Growth of the JDAM family of weapons expanded to the 500 pound (230 kg) Mark 82 kit, which began development in late 1999. Also, the Navy is currently studying the effects of adding enhancements such as improved GPS accuracy as well as a precision seeker for terminal guidance for use against moving targets and additional warheads.

JDAM bombs are inexpensive compared to alternatives such as cruise missiles. The original cost estimate was $40,000 each for the tail kits, but after competitive bidding, contracts were signed with McDonnell Douglas (later overtaken by Boeing) for delivery at $18,000 each. In subsequent years, unit costs increased modestly to $21,000 in 2004 and were expected to reach $31,000 by 2011.[5] For comparison, the newest Tomahawk cruise missile, dubbed the Tactical Tomahawk, costs nearly $730,000 apiece.[6][7]

JDAMs loaded under the left wing of a F-16 Fighting Falcon with a LITENING II Targeting Pod visible beneath the fuselage
JDAMs loaded under the left wing of a F-16 Fighting Falcon with a LITENING II Targeting Pod visible beneath the fuselage

Guidance is facilitated through a tail control system and a GPS-aided inertial navigation system (INS). The navigation system is initialized by transfer alignment from the aircraft that provides position and velocity vectors from the aircraft systems. Once released from the aircraft, the JDAM autonomously navigates to the designated target coordinates. Target coordinates can be loaded into the aircraft before takeoff, manually altered by the aircrew in flight prior to weapon release, or entered by a datalink from onboard targeting equipment, such as the LITENING II Targeting Pod. In its most accurate mode, the JDAM system will provide a minimum weapon accuracy CEP of 13 meters or less when a GPS signal is available, though Boeing and the Air Forces report less than 10 meters CEP in testing. If the GPS signal is jammed or lost, the JDAM can still achieve a 30 meter CEP or less for free flight times up to 100 seconds.[8]

JDAM can be launched from very-low to very-high altitudes in a dive, toss-and-loft, or in straight-and-level flight, with an on-axis or off-axis delivery. JDAM enables multiple weapons to be directed against single or multiple targets on a single pass. The JDAM system permits variable fuzing, from air-burst through contact- and penetration-fuzing, making it a versatile guidance system.[8] Fuzing must be set prior to takeoff, as the aircrew have no way to adjust this in flight.

Despite their precision, JDAM employment is not without risk. On December 5, 2001, a JDAM dropped by a B-52 in Afghanistan nearly killed Hamid Karzai, now the country's president, while he was leading anti-Taliban forces near Sayd Alim Kalay alongside a US Army Special Forces (SF) team. A large force of Taliban had engaged the combined force of Karzai's men and their American SF, nearly overwhelming them. The SF commander requested Close Air Support (CAS) to strike the Taliban positions in an effort to stop their advance. A JDAM was launched to fulfill the CAS request, but instead of striking the Taliban positions, it struck the Afghan/American position. The subsequent investigation of the incident determined that the terminal attack controller attached to the Special Forces team had changed the battery in the GPS receiver at some point during the battle, thereby causing the device to return to "default" and "display its own coordinates." As a result, the improper target coordinates were relayed to the delivery aircraft, and the bomb targeted the Afghani and American position, rather than the Taliban forces.[9] This incident resulted in three American soldiers and five allied Afghans were killed, with over forty others injured.

U.S. military experience during Operation Enduring Freedom and Operation Iraqi Freedom highlighted the need for an even more accurate delivery of bombs.[10] The Laser JDAM (LJDAM) adds a laser seeker to the nose of a JDAM equipped bomb, allowing for highly precise terminal guidance, allowing for a CEP of 3 meters, with the ability to strike a moving target. During FY2004, the Boeing and the U.S. Air Force began testing of the laser guidance capability for JDAM. These tests demonstrated that the system is capable of targeting and destroying moving targets.[11] The weapon retains the ability to operate on GPS/INS alone, if laser guidance is unavailable, with the same accuracy of the earlier JDAM.

On 11 June 2007, Boeing announced that it had been awarded a $28 million contract by the U.S. Air Force to deliver 600 laser seekers (400 to the Air Force and 200 to the Navy) by June 2009.[12] According to the Boeing Corporation, in tests at Nellis Air Force Base, Nevada, Air Force F-16 Fighting Falcons and F-15E Strike Eagles dropped twelve (12) 500 pound (230 kg) LJDAMs that successfully struck high-speed moving targets. Using onboard targeting equipment, the launch aircraft self-designated, and self-guided their bombs to impact on the targets. In addition to the LJDAM kits, Boeing is also testing under a Navy development contract, an anti-jamming system for the JDAM, with development expected to be completed during 2007, with deliveries to commence in 2008.[13] The system is known as the Integrated GPS Anti-Jam System (IGAS).

JDAMs loaded onto a Multiple Ejector Rack under the wing of a B-52H Stratofortress
JDAMs loaded onto a Multiple Ejector Rack under the wing of a B-52H Stratofortress

JDAM is currently compatible with:

Follow-on integration efforts are currently underway or planned to evaluate compatibility with:

The U.S. Government has approved the JDAM for export sale under the Arms Export Control Act, though in limited numbers to only a few countries. Outstanding requests for purchase are under review.

  • Primary function: Guided air-to-surface weapon
  • Contractor: Boeing
  • Length: (JDAM and warhead) GBU-31 (v) 1/B: 152.7 in (3879 mm); GBU-31 (v) 3/B: 148.6 in (3774 mm); GBU-32 (v) 1/B: 119.5 in (3035 mm)
  • Launch weight: (JDAM and warhead) GBU-31 (v) 1/B: 2,036 lb (925 kg); GBU-31 (v) 3/B: 2,115 lb (961 kg); GBU-32 (v) 1/B: 1,013 lb (460 kg)
  • Wingspan: GBU-31: 25 in (635 mm); GBU-32: 19.6 in (498 mm)
  • Range: Up to 15 miles (24 km)
  • Ceiling: 45,000 ft (13,700 m)
  • Guidance system: GPS/INS
  • Unit cost: Approximately $21,000 per tailkit (FY 01 dollars)
  • Date deployed: 1999
  • Inventory: The tailkit is in full-rate production. Projected inventory is approximately 240,000 total, 158,000 for the US Air Force and 82,000 for the US Navy. (As of October 2005)

USAF artist rendering of JDAM kits fitted to Mk 84, BLU-109, Mk 83, and Mk 82 iron bombs.
USAF artist rendering of JDAM kits fitted to Mk 84, BLU-109, Mk 83, and Mk 82 iron bombs.

  1. ^ JDAM continues to be warfighter's weapon of choice. Retrieved on 2007-07-27.
  2. ^ JDAM: The Kosovo Experience and DPAS, The Boeing Company, Charles H. Davis, 19 April 2000, <http://guidebook.dcma.mil/38/dpas/12DavisPres.pdf>. Retrieved on 2007-09-01
  3. ^ a b The Boeing Company (17 September 2003). U.S. Air Force B-2 Bomber Drops 80 JDAMS in Historic Test. Press release. Retrieved on 2007-09-02.
  4. ^ Myers, Dominique (2002), "Acquisition Reform-Inside The Silver Bullet", Acquisition Review Journal IX, no. 2 (Fall 2002): 312-322, <http://www.dau.mil/pubs/arq/2002arq/MyersFL02.pdf>. Retrieved on 2007-09-01
  5. ^ [http://www.finance.hq.navy.mil/fmb/06pres/proc/PANMC_Book.pdf DEPARTMENT OF THE NAVY FISCAL YEAR (FY) 2006/FY 2007 BUDGET ESTIMATES]
  6. ^ "The JDAM Revolution" article by Peter Grier in Air Force Online, the journal of the Air Force Association, September, 2006
  7. ^ "BGM-109 Tomahawk: Variants". Retrieved on 2007-07-27.
  8. ^ a b USAF Factsheet: JOINT DIRECT ATTACK MUNITIONS. Retrieved on 2007-07-27.
  9. ^ Killing Your Own: The Problem of Friendly Fire During the Afghan Campaign. Retrieved on 2007-07-27.
  10. ^ Dual Mode Guided Bomb. Retrieved on 2007-07-27.
  11. ^ Boeing Scores Direct Hit in Laser JDAM Moving Target Test. Retrieved on 2007-07-27.
  12. ^ The Boeing Company (11 June 2007). Boeing Awarded Laser JDAM Contract. Press release. Retrieved on 2007-09-02.
  13. ^ The Boeing Company (18 June 2007). Boeing Completes JDAM Anti-Jamming Developmental Flight Test Program. Press release. Retrieved on 2007-09-02.
  14. ^ First International JDAM Sale: Boeing to Integrate Weapon on Israeli Aircraft. Retrieved on 2007-07-27.
  15. ^ global security.org. Retrieved on 2007-07-27.
  16. ^ boeing.com Boeing JDAM Wins Australian Competition. Retrieved on 2007-07-27.
  17. ^ Norway Signs Contract for Boeing JDAM. Retrieved on 2007-07-27.
  18. ^ Dutch secretary of defense details plan for purchase of JDAM's. Retrieved on 2007-07-27.
  19. ^ Gates says Washington to sell smart bombs to Saudi Arabia. Retrieved on 2007-07-27.
  20. ^ FMS: Third Phase of Finnish F/A-18 MLU. Retrieved on 2007-07-27.
  21. ^ FMS: Pakistan New F-16C/D Block 50/52 Aircraft. Retrieved on 2007-07-27.
  22. ^ FMS: Greece - F-16C/D Munitions. Retrieved on 2007-07-27.

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