The original Titan IV design, now known as Titan IVA, employs solid rocket motors manufactured by United Technologies. Titan IVA can place up to 31,100 pounds into a polar low earth orbit. With the Centaur upper stage, Titan IVA can lift 10,000 pounds into a geosynchronous earth orbit. An improved Titan IV design, designated Titan IVB, made its maiden flight in February 1997. Improvements to the Titan IVB vehicle include the solid rocket motor upgrade manufactured by Alliant Techsystems, new guidance and avionics, standardized payload interfaces, and a new flight termination system. Titan IVB improved lift capacity to low earth orbit is 38,800 pounds. Titan IVB with Centaur can place 11,500 pounds into geosynchronous earth orbit.

The Air Force operates Titan IV launch complexes at Cape Canaveral Air Station, FL, and Vandenberg Air Force Base, CA. As the nation's heavy lift space launch system, Titan IV is an example of technological innovation being used to secure our nation's assured access to space. Titan delivers payloads to precise orbits, executing full-dimensional protection through the high ground of space.

Titan IV development was authorized by National Security Decision Directive 164 to ensure heavy lift access to space comparable to space shuttle payload capacity. Titan IV development began with a contract award to Martin Marietta (now Lockheed Martin) in February 1985. Titan IV is an outgrowth of the Titan family of intercontinental ballistic missiles and the Titan 34D medium payload launch vehicle. Initial launch capability was achieved with the first launch in June 1989. The Titan IVB/solid rocket motor upgrade program was initiated in 1987 to improve payload performance and system reliability. Titan IVB initial launch capability was achieved with the first Titan IVB launch in February 1997. Twenty-five Titan IV/A and B launches have been conducted prior to FY97, with 23 of the flights successful. The two launch failures occurred in the Titan IVA version. To date, all three Titan IVB launches have been successful.

AFOTEC conducted an OA from 1993-1995. While Titan IV performance met user needs, the assessment was too brief to demonstrate compliance with all operational requirements.

Titan IVA experienced two launch failures in 22 attempts (August 2, 1993-August 12, 1998). The 1998 failure occurred on the final flight of the Titan IVA vehicle when the rocket exploded approximately 42 seconds after liftoff. The cause of the failure is currently under investigation. With 23 successes in 25 attempts, the overall (Titan IVA and IVB) observed launch and in-flight reliability is 92 percent compared to the Operational Requirements Document (ORD) requirement of 96 percent. Once flight operations were resumed following the failure in 1993, overall reliability and launch throughput rates for Titan IVA improved. The Titan IVB currently has a 100 percent reliability rate, but this is based on only three launches to date.

Three launches were conducted from Vandenberg Air Force Base during the period December 6, 1995-December 20, 1996, exceeding the ORD requirement rate of two launches per year from the west coast. Eight Cape Canaveral Air Station launches were made over the period from February 7, 1994-April 24, 1996, for a demonstrated rate of 3.6 launches per year, falling just short of the ORD requirement of four launches per year from the east coast.

The Titan IVB/solid rocket motor upgrade has now flown successfully three times (February and October 1997 and May 1998). DOT&E continues to monitor vehicle launch and in-flight reliability, annual launch throughput rates, and the progress of Titan IVB. However, there are no dedicated operational tests planned for the remaining launches in the Titan IV program.

The Program Office plans to complete Y2K certification of the Titan rocket, subsystems, critical interfaces, and support equipment by mid-1999.

Point estimates of the launch throughput rate at Cape Canaveral Air Station, and vehicle launch and in-flight reliability, still fall slightly below ORD thresholds. However, there are grounds for cautious optimism. The gaps are small and have been closing in recent years. Questions of reliability and throughput rates are complex and may be affected by a host of factors not captured in simple calculations of predefined metrics. For example, launch rates are obviously affected by the demand for missions to orbit. If demand is low, the launch rate will also be low. Given the expense of Titan IV operations, the best available approach to a better understanding these and other complex issues is to continue to monitor and analyze real-world Titan IV operations.

Titan IV operations offer many potential lessons for the Evolved Expendable Launch Vehicle program under development. This is particularly true of suitability issues such as pre-launch operations, range support operations, and other associated operations. Opportunities for Titan IV site visits in support of Evolved Expendable Launch Vehicle T&E planning are currently under exploration.