The US Air Force is delaying the retirement of the Lockheed Martin Titan IV fleet beyond the phase-out in 2002 with the last ordered booster not flying until 2004. There are only two Titan IV launch sites at Cape Canaveral, Florida, and Vandenberg AFB, California, and the turnaround between launches is usually six months. A second Titan IV pad at Canaveral has been refurbished to accommodate Lockheed's Atlas V Evolved Expendable Launch Vehicle.
The first Titan IV was launched in 1989 and three models of each of IVA and IVB versions have made 25 successful flights and five failed launches.
Source: Flight International