The U.S. Air Force and the United Launch Alliance are scheduled to launch GPS IIF satellite 5 Feb. 20 on a Delta IV rocket from Space Launch Complex 37 Cape Canaveral, Fla., the first of three planned launches through July 2014.

The launch comes before final reports have been filed regarding an investigation into the 2012 Delta IV launch in which an upper stage RL10B-2 engine experienced low thrust. Final reports from the Air Force and ULA, as well as an accident investigation board report directed by Air Force Space Command Commander Gen. William Shelton, are anticipated in April, says Col. William Hodgkiss, launch systems director.

The team has made some process improvements including adding inspections of the engine and the launch vehicle systems connected to the engine “to be absolutely sure that they are pristine and clean,” says Jim Sponnick, vice president of United Launch Alliance’s Atlas and Delta Programs. Improvements to how the engine system is conditioned during the boost phase and prepared for the first ignition are also planned, he says.

The satellite will replace a GPS IIA satellite that is 16 years old. “We’re trying to prevent any kind of outage,” says Col. William Cooley, Global Positioning Systems director. The Air Force currently supports 31 satellites on orbit that are healthy and after this launch will have an additional six in residual status.

A backup date for this launch is Feb. 21. After this launch, the service is approved to launch another satellite May 15 and expects to schedule another in July. The Boeing-made IIF series includes 12 satellites.

Like previous GPS IIF satellites, this one adds the “L5” signal of interest to the aviation community. It increases the power over previous navigational signals and is expected to improve safety of life and assist in search-and-rescue efforts.