Precision-guided munition

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BOLT-117, the world's first laser-guided bomb

A precision-guided munition (PGM, smart weapon, smart munition, smart bomb) is a guided munition intended to precisely hit a specific target, and to minimize collateral damage.[1]

Because the damage effects of explosive weapons decrease with distance due to an inverse cube law, even modest improvements in accuracy (hence reduction in miss distance) enable a target to be attacked with fewer or smaller bombs. Thus, even if some guided bombs miss, fewer air crews are put at risk and the harm to civilians and the amount of collateral damage may be reduced.

The advent of precision-guided munitions resulted in the renaming of older bombs "unguided bombs", "dumb bombs", or "iron bombs".


Main article: missile guidance
A laser-guided GBU-24 (BLU-109 warhead variant) strikes its target.

Recognizing the difficulty of hitting moving ships during the Spanish Civil War,[2] the Germans were first to develop steerable munitions, using radio control or wire guidance. The U.S. tested TV-guided (GB-4),[3] semi-active radar-guided (Bat), and infrared-guided (Felix) weapons.

Radio-controlled weapons[edit]

Main article: command guidance

The Germans were first to introduce PGMs in combat, with the 1,400-kg (3,100-lb) MCLOS-guidance Fritz X armored gravity ordnance, to successfully attack the Italian battleship Roma in 1943 and sink a hospital ship at Anzio, and the similarly MCLOS-guided Henschel Hs 293 rocket-boosted glide missile (also in use since 1943, but only against lightly armored or unarmored ship targets). The closest Allied equivalents were the 1,000-lb (454-kg) VB-1 AZON (AZimuth ONly), used in both Europe and the CBI theater, and the US Navy's Bat, primarily used in the Pacific Theater of World War II—the Navy's Bat had its own on board, autonomous radar seeker system to direct it to a target. In addition, the U.S. tested the rocket-propelled Gargoyle, which never entered service.[4] Japanese PGMs—with the exception of the anti-ship air-launched, rocket-powered, human-piloted Ohka suicide flying bomb—did not see combat in World War II.

Prior to the war, the British experimented with radio-controlled remotely guided planes laden with explosive, such as Larynx. The United States Army Air Forces used similar techniques with Operation Aphrodite, but had few successes; the German Mistel (Mistletoe) "parasite aircraft" was no more effective, guided by the human pilot flying the single-engined fighter mounted above the unmanned, explosive-laden twin engined "flying bomb" below it, released in the Mistel's attack dive from the fighter.


Although not as popular as the newer JDAM and JSOW weapons, or even the older laser-guided bomb systems, weapons like the AGM-62 Walleye TV-guided bomb are still being used, in conjunction with the AAW-144 Data Link Pod, on US Navy F/A-18 Hornets.

Infrared-guided/electro-optical weapons[edit]

Main article: Infrared homing

In World War II, the U.S. National Defense Research Committee developed the VB-6 Felix, which used infrared to home on ships. While it entered production in 1945, it was never employed operationally.[5] Precision guidance has been applied to weapons other than conventional bomb warheads. The Raytheon Maverick heavy anti-tank missile has among its various marks guidance systems such as electro-optical (AGM-65A), imaging infra-red (AGM-65D), and laser homing (AGM-65E).[6] The first two, by guiding themselves based on the visual or IR scene of the target, are fire-and-forget in that the pilot can release the weapon and it will guide itself to the target without further input, which allows the delivery aircraft to manoeuvre to escape return fire. The Israeli Elbit Opher is also an I.R imaging "drop and forget" guided bomb that has been reported to be considerably cheaper than laser-homing bombs and can be used by any aircraft, not requiring specialized wiring for a laser designator or for another aircraft to illuminate the target. During NATO's air campaign in 1999 in Kosovo the new Italian AF AMX employed the Opher.[7]

Laser-guided weapons[edit]

Main article: Laser-guided bomb
Diagram showing the operation of a laser-guided ammunition round. From a CIA report, 1986.





Main article: radar guidance


Satellite-guided weapons[edit]

A F-22 releases a JDAM from its center internal bay while flying at supersonic speed
HOPE/HOSBO of the Luftwaffe with a combination of GPS/INS and electro-optical guidance

Lessons learned during the first Gulf War showed the value of precision munitions, yet they also highlighted the difficulties in employing them—specifically when visibility of the ground or target from the air was degraded.[10] The problem of poor visibility does not affect satellite-guided weapons such as Joint Direct Attack Munition (JDAM) and Joint Stand-Off Weapon (JSOW), which make use of the United States' GPS system for guidance. This weapon can be employed in all weather conditions, without any need for ground support. Because it is possible to jam GPS, the guidance package reverts to inertial navigation in the event of GPS signal loss. Inertial navigation is significantly less accurate; the JDAM achieves a published Circular Error Probable (CEP) of 13 m under GPS guidance, but typically only 30 m under inertial guidance (with free fall times of 100 seconds or less).[11][12]

The precision of these weapons is dependent both on the precision of the measurement system used for location determination and the precision in setting the coordinates of the target. The latter critically depends on intelligence information, not all of which is accurate. According to a CIA report, the accidental United States bombing of the Chinese embassy in Belgrade during Operation Allied Force by NATO aircraft was attributed to faulty target information.[13] However, if the targeting information is accurate, satellite-guided weapons are significantly more likely to achieve a successful strike in any given weather conditions than any other type of precision-guided munition.

Advanced guidance concepts[edit]

Responding to after-action reports from pilots who employed laser or satellite guided weapons, Boeing developed a Laser JDAM (LJDAM) to provide both types of guidance in a single kit. Based on the existing Joint Direct Attack Munition configurations, a laser guidance package is added to a GPS/INS-guided weapon to increase its overall accuracy.[14] Raytheon has developed the Enhanced Paveway family, which adds GPS/INS guidance to their Paveway family of laser-guidance packages.[15] These "hybrid" laser and GPS guided weapons permit the carriage of fewer weapons types, while retaining mission flexibility, because these weapons can be employed equally against moving and fixed targets, or targets of opportunity. For instance, a typical weapons load on an F-16 flying in the Iraq War included a single 2,000-lb JDAM and two 1,000-lb LGBs. With LJDAM, and the new Small Diameter Bomb, these same aircraft can carry more bombs if necessary, and have the option of satellite or laser guidance for each weapon release.

Cannon-launched guided projectiles[edit]

A cannon-launched guided projectile (CLGP), a precursor to modern PGMs, is fired from artillery, ship's cannon, or armored vehicles. Several agencies and organizations sponsored the CLGP programs. The United States Navy sponsored the Deadeye program, a laser-guided shell for its 5" guns[16] and a program to mate a Paveway guidance system to an 8" shell[17] for the 8"/55 caliber Mark 71 gun in the 1970s (Photo). Other Navy efforts include the BTERM, ERGM, and LRLAP shells.

The U.S. Army's MGM-51 Shillelagh missile can be considered a type of CLGP. Intended for use on the M551 Sheridan light tank, the Shillelagh missile was fired out of the Sheridan's cannon to provide robust anti-tank capability. The Army's M712 Copperhead laser guided artillery round was used in Desert Storm. Army CLGPs include the M982 Excalibur 155mm artillery shell, the XM395 Precision Guided Mortar Munition, and the XM1156 Precision Guidance Kit to refit existing 155mm shells with precision guidance, as the Air Force's JDAM program converts dumb bombs into precision munitions.

Guided small arms[edit]

Precision-guided small arms prototypes have been developed which use a laser designator to guide an electronically actuated bullet to a target.[18] Another system in development uses a laser range finder to trigger an explosive small arms shell in proximity to a target. The U.S. Army plans to use such devices in the future.[19]

See also[edit]


  1. ^ Hamilton, Richard (1995). "Precision guided munitions and the new era of warefare". Air Power Studies Centre, Royal Australian Air Force. Retrieved 2009-02-02. 
  2. ^ Fitzsimons, Bernard, editor. The Illustrated Encyclopedia of 20th Century Weapons and Warfare (London: Phoebus, 1978), Volume 10, p.1037, "Fritz-X".
  3. ^ Fitzsimons, op. cit., Volume 10, p.1101, "GB-4".
  4. ^ Fitzsimons, op. cit., Volume 10, p. 1090, "Gargoyle".
  5. ^ Fitzsimons, op. cit., Volume 9, p. 926, "Felix".
  6. ^ Raytheon AGM-65 Maverick
  7. ^ "Opher bomb deployed in Kosovo" FLIGHT Daily News, 17 June 1999
  8. ^ Thanh Hoa Bridge
  9. ^ Britain's Small Wars
  10. ^ JDAM continues to be warfighter's weapon of choice
  11. ^ U.S. Air Force Factsheets: Joint Direct Attack Munition
  12. ^ John Pike. "Joint Direct Attack Munition (JDAM)". Retrieved 1 April 2015. 
  13. ^ DCI Statement on the Belgrade Chinese Embassy
  14. ^ "Weapons" (PDF). Retrieved 1 April 2015. 
  15. ^ Raytheon Enhanced Paveway
  16. ^ "USA 5"/54 (12.7 cm) Mark 42". Retrieved 1 April 2015. 
  17. ^ "USA 8"/55 (20.3 cm) Mark 71". Retrieved 1 April 2015. 
  18. ^ "Sandia's self-guided bullet prototype can hit target a mile away". 

External links[edit]