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The B-1B is a modified B-1A with major revisions in offensive avionics, defensive avionics, weapon payload, range, and speed. These modifications were made to incorporate certain technological advances that had occurred between the original B-lA contract award in 1970 and the LRCA competition in 1980. Improvements consist primarily of off-the-shelf technology such as a new radar, new generation computers, expanded ECM capabilities, reduced RCS, and avionics compatibility with the ALCM. The wing sweep is restricted to 60 which limits the maximum speed to just above supersonic. Rockwell also estimated range increases for the modified B-1.

Differences between the B-1B and its predecessor, the B-1A of the 1970s, are subtle, yet significant. Externally, only a simplified engine inlet, modified over-wing fairing and relocated pilot tubes are noticeable. Other less-evident changes include a window for the offensive and defensive systems officers' station and engine housing modifications that reduces radar exposure. The B-1B was structurally redesigned to increase its gross takeoff weight from 395,000 to 477,000 pounds (177,750 to 214,650 kilograms). Still, the empty weight of the B-1B is but 3 percent greater than that of the B-1A. This added takeoff weight capacity, in addition to a movable bulkhead between the forward and intermediate weapons bay, allows the B-1B to carry a wide variety of nuclear and conventional munitions. The most significant changes, however, are in the avionics, with low-radar cross-section, automatic terrain-following high-speed penetration, and precise weapons delivery.

Prior to 1994 B-1B fleet had never achieved its objective of having a 75-percent mission capable rate. In 1992 and 1993 the B-1B mission capable rate averaged about 57 percent. According to the Air Force, a primary reason for the low mission capable rate was the level of funding provided to support the B-1B logistics support system. Concerned about the low mission capable rate, a history of B-1B problems, and the Air Force's plans to spend $2.4 billion modifying the B-1B to become a conventional bomber, the Congress directed the Air Force to conduct an Operational Readiness Assessment (ORA) from June 1, 1994, through November 30, 1994. The purpose of the ORA was to determine whether one B-1B wing was capable of achieving and maintaining its planned 75-percent operational readiness rate for a period of 6 months, if provided the full complement of spare parts, maintenance equipment and manpower, and logistic support equipment. During the ORA the test unit achieved an 84.3-percent mission capable rate during the test period. The ORA demonstrated that, given a full complement of spare parts, equipment, and manpower, the Air Force could achieve and sustain a 75-percent mission capable rate for the B-1B. The Air Force projects that the entire B-1B fleet will reach a 75-percent mission capable rate by 2000 by virtue of numerous on-going and future reliability, maintainability, and management initiatives. However, as of mid-October 1999 the Air Force wide mission capable rate of the B-1 had fallen to 51.1 percent -- mainly because of maintenance problems and a shortage of parts. Over the previous 12 months, the Kansas Guard had maintained a mission capable rate of 71.1 percent for the 10 usable aircraft assigned to it. Overall, the B-1B had mission capable rates of 51 percent to 62 percent in FY'00 and FY'01, below the goal of 75-percent.

 The basis for the projection of useful life of the B-1 is the Aircraft Structural Integrity Program (ASIP). The useful life of the structure is assumed to be the point at which it is more economical to replace the aircraft than to continue structural modifications and repairs necessary to perform the mission. The limiting factor for B-1’s service life is the wing lower surface. At 15,200 hours, based on continued low level usage, the wing’s lower skin will need replacement. Current usage rates, operational procedures, and mishap attrition will place the inventory below the requirement of 89 aircraft in 2018, while the service life attrition will impact around 2038.

The first B-1B, 83-0065, The Star of Abilene, was delivered to the Air Force at Dyess Air Force Base, Texas, in June 1985, with initial operational capability on Oct. 1, 1986. The 100th and final B-1B was delivered May 2, 1988.

The Air Force chose to fully fund the operation of only 60 B-1Bs in the mid-1990s, compared with plans to fund 82 beyond fiscal year 2000. In the short term, the Air Force classified 27 of 95 B-1Bs as "reconstitution aircraft." These aircraft were not funded for flying hours and lacked aircrews, but they are based with B-1B units, flown on a regular basis, maintained like other B-1Bs, and modified with the rest of the fleet. B-1B units used flying hours and aircrews that were based on 60 operational aircraft to rotate both the operational aircraft and the reconstitution aircraft through its peacetime flying schedule. These 27 aircraft were maintained in reconstitution reserve status until the completion of smart conventional munition upgrades. By that time [around the year 2000], there were 95 aircraft providing an operational force of 82 fully modified B-1s. The B-1 will complete its buy back of attrition reserve by the fourth quarter of FY03, and re-code six training aircraft to attain 70 combat-coded aircraft by the fourth quarter of FY04.

During the Cold War, heavy bombers were used primarily for nuclear deterrence and were operated solely by the active duty Air Force. According to the Air Force, the National Guard's part-time workforce was incompatible with the bombers' nuclear mission because of a requirement for continuously monitoring all personnel directly involved with nuclear weapons. With the end of the Cold War and increased emphasis on the bombers' conventional mission, the Air Force initiated efforts to integrate Guard and reserve units into the bomber force. As part of its total force policy, the Air Force assigned B-1B aircraft to the National Guard. Heavy bombers entered the Air Guard's inventory for the first time in 1994 with a total of 14 B-1Bs programmed by the end of fiscal year FY 1997 for two units, the 184th Bomb Wing (BW), Kansas, and the 116th BW, Georgia. The 184th completed its conversion in FY 1996 at McConnell Air Force Base (AFB), Kansas. After a long political struggle that involved resisting the planned conversion from F-15s and an associated move from Dobbins AFB near Atlanta to Robins AFB near Macon, the 116th began its conversion on 1 April 1996. The unit completed that process in December 1998. All the bombers in both units were configured for conventional, not nuclear, missions.

Prior to 1994, the B-1B fleet operated out of four bases: Dyess Air Force Base, Texas; Ellsworth Air Force Base, South Dakota; McConnell Air Force Base, Kansas; and Grand Forks Air Force Base, North Dakota. In 1994, the Air Force realigned the B-1B fleet by closing the Grand Forks Air Force Base and transferring the aircraft at McConnell Air Force Base to the Air National Guard. With the transfer, the B-1B support structure, including spare parts, was distributed to the two remaining main operating bases. The concentration of aircraft and repair facilities at Dyess and Ellsworth Air Force Bases resulted in improved support capabilities, which improved mission capable [MC] rates.

On 26 March 1996 it was announced that the 77th Bomb Squadron would return to Ellsworth. On 1 April 97, the squadron again activated at Ellsworth as the geographically separated 34th Bomb Squadron completed its transfer to its home at the 366th Wing, Mountain Home AFB, Idaho. By June 1998, the 77th had six of its B-1Bs out of the reconstitution reserve. This number ballanced those lost by the 34th BS.
The Advanced Conventional Bomb Modules [ACBM] were uniquely designed to meet the needs of the B-1B aircraft during the transition between Block D and Block E. All the munitions personnel have to do is switch a circuit card and one cable, and the modules will be ready for Block E. With the upgrade, the B-1B's will be able to employ Wind Corrected Munitions Dispensers and will still be able to carry Mk-82, 500-pound bombs and cluster bomb units. The upgrade helps weapons loading capabilities keep up with changes to the aircraft's on-board computer systems. The aircraft are upgrading from 1970's vintage computers to the capability of today's computers," he said. "This upgrade also includes a new avionics flight software package. With this upgrade, operators needed new bomb modules that were compatible with the new computers.

The 28th Munitions Squadron received shipment of the first two of 13 new Advanced Conventional Bomb Modules 03 April 2000, taking the B-1B one step closer to Block E integration. The new ACBMs differ from the ones currently used as the new modules already have the wiring and electronics capability required to handle Block E weapons upgrades. A bomb module seats inside an aircraft bomb bay and is configured to hold different types and sizes of bombs. Ellsworth is the first bomber base to receive the new modules. The new ACBMs were available for use by base bomb squadrons in mid-May 2000, and the remaining modules were delivered by mid-September 2000.

Cockpit Upgrade Program (CUP) - Current B-1 cockpit display units are not capable of supporting graphic intensive software modifications. The CUP installs a robust graphic capability via common display units throughout the front and aft stations. This program increases B-1 survivability by providing critical situational awareness displays, needed for conventional operations, keeping pace with current and future guided munitions integration, enhancing situational awareness, and improving tactical employment.

Link-16 – Providing Line-of-Sight (LOS) data for aircraft-to-aircraft, aircraft-to-C2, and aircraft-to-sensor connectivity, Link-16 is a combat force multiplier that provides U.S. and other allied military services with fully interoperable capabilities and greatly enhances tactical Command, Control, Communication, and Intelligence mission effectiveness. Link-16 provides increased survivability, develops a real-time picture of the theater battlespace, and enables the aircraft to quickly share information on short notice (target changes). In addition to a localized capability, the B-1’s datalink will include BLOS capability increasing flexibility essential to attacking time-sensitive targets.

B-1 Radar Upgrade is a candidate Long Term Upgrade that would improve the current Synthetic Aperture Radar resolution from three meters to one foot or better, allowing the B-1 to more autonomously and precisely Find, Fix, Target, Track, Engage, and Assess enemy targets with guided direct-attack or standoff munitions (JDAM/JSOW). Finally, the upgrade would replace older components that will be difficult to maintain due to obsolescence and vanishing vendors.

The B-One Next Enhancement (BONE) effort will include the integration and responsibility for future enhancements or improvements to the B-1 weapon system. The B-1 System Program Office (ASC/YD) announced in January 2001 that it contemplates awarding a single over-arching contract for acquisition and sustainment of the B-1 weapon system. The contract may include level of effort and discrete tasks for enhancement and sustainment activities to support product support, sustaining engineering, software support, technical data, Diminishing Manufacturing Sources (DMS) support, initial spares and support equipment as well as enhancements or improvement efforts for upgrades to the weapon system.

The Government cannot predetermine at the project level the precise B-1 aircraft acquisition and sustainment requirements or improvements to be acquired. Enhancements/upgrades/acquisitions may include, but not limited to, development and production of cockpit display upgrades, integrated Link 16, beyond line of sight UHF SATCOM datalinks, radar upgrades, vertical situation display replacement, gyro stabilization system upgrade, on-board diagnostics hardware upgrade, electro-multiplexing system upgrade, automatic test system upgrades, GATM upgrades, GPS modernization, ALQ-161A reliability and maintainability upgrades, defensive system upgrade, computer avionics upgrade, weapon integration upgrades, conventional bomb modules 1760 conversion upgrades, mission planning system upgrades/conversions, IFF system upgrades, digital flight control (including central air data computer) enhancement, B-1 unique support equipment, and associated B-1 weapon system software changes.

The estimated maximum amount for the acquisition is anticipated to be $2.4 Billion. Anticipated award date was 01 March 2002 for a portion of the effort. This single over-arching contract for the weapon system will contain multiple contract types at the contract line item level (e.g., cost-plus incentive fee, firm fixed price, time & materials, etc.) to accommodate a wide range of potential tasks. Contract efforts are subject to FAR 52.232-18 availability of funds.

The requirements for this acquisition are further defined in terms of functions to be performed relative to the acquisition of upgrades and sustainment efforts for the B-1 weapon system. Sufficient capability to integrate B-1 weapon system must exist to perform at a minimum ALL of the following related tasks: Provide interim contractor repair on programmed and known/unknown non-programmed B-1 weapon system items identified for repair/modification. Product support requires the contractor to identify, evaluate and recommend solutions to resolve B-1 weapon system hardware and software technical and supportability anomalies, deficiencies, and problems. Integrate hardware modifications with software and testing to verify proposed engineering problem solutions. Provide software support efforts required to analyze software change requests, and field anomalies. Design, code, and test software changes (including block changes) to the B-1 aircraft weapon system and ground support systems. Included in this effort is the integration of the software with the B-1 weapons system to include administrative support, interface with flight test organizations, manufacture of firmware, and compliance with Air Force retrofit processes. Identify and evaluate impacts to AF Mission Planning Systems, B-1 Training System, and associated ancillary equipment include identifying and evaluating impacts to those systems resulting from air vehicle anomalies, field anomalies and software/hardware block changes. Develop, deliver and maintain B-1 system related technical data as required. At a minimum provide maintenance of the Paperless CDRL Delivery System (PCDS) for Government and B-1 training system prime contractor to access all B-1 program data electronically. Perform weapon system enhancements or improvement efforts to support at a minimum all B-1 weapon system upgrades including development, test, production, retrofit modifications and related Type 1 training.