The Rockwell B-1B Lancer traces its origins to the B-1A prototype strategic bomber of the 1970s. The basic B-1A design was much revised, and resulted in 100 production B-1B Lancers, the first of which flew in production form on 18 October 1984.
The B-1B has variable geometry outer wing panels, some degree of stealthiness and is optimised for the low-level, high-speed penetration role against sophisticated air-defence systems with the aid of comprehensive countermeasures systems. The primary offensive system is the APQ-164 multi-mode radar, which includes a low-observable phased-array antenna for low-altitude terrain following and accurate navigation.
With the end of the Cold War, the B-1B lost its nuclear strike role and was re-roled instead for conventional warfare. The B-1B's ability to carry up to 34020 kg of bombs internally - more than any other bomber - gives an added flexibility to the USAF's combat operations. At the heart of this re-roling is the Conventional Munitions Upgrade Programme (CMUP). Segmented into blocks, this was designed to expand the B-1's lethality, survivability and maintainability as a conventional bomber. Block C provided for the carriage of a range of cluster bombs (CEM, Gator and SFW); Block D added GBU-31 Joint Direct-Attack Munitions compatibility, as well as a new countermeasures system (including ALE-50 towed decoy) and a new comms/navigation system; Block E, became operational in 2003, adds a precision strike ability with the WCMD, JSOW and JASSM weapons; Block F will witness further improvements in defensive capability (including ALE-55 decoy) for service from 2003 and completion in 2009.
Weapons are carried on preloaded gun-clip-type modules or rotary launchers. The B-1B saw its combat debut over Iraq during Desert Fox on 17 December 1998 but really proved its worth during Allied Force in 1999, during which aircraft deployed from the UK dropped around 5 000 Mk 82 bombs. Around 70 Lancers are available for operations at any one time, dispersed between three wings of USAF Air Combat Command and two wings of the Air National Guard.