Root Cause

Air Force Space Command has decided to convene an accident investigation board (AIB) to look into the flawed but ultimately successful launch of a Global Positioning System satellite last week.

The third GPS IIF satellite was launched from Cape Canaveral Air Force Station, FL, on Oct. 4 aboard a Delta IV rocket booster, but the Delta IV's upper-stage engine -- an RL10-B-2 engine manufactured by Pratt & Whitney Rocketdyne -- did not deliver as much thrust as expected. As a result, GPS IIF-3 took longer to reach its orbital location than planned.

The United Launch Alliance is the Air Force's launch provider for medium-class payloads like GPS satellites.

According to an Oct. 11 command statement, the near-term launch manifest is under review “while the root cause of the unexpected performance of the RL10-B-2 engine is determined.”

“While the launch was ultimately successful, the time-honored rigor and earnest process of an AIB will serve us well as we attempt to determine the root cause of this anomaly,” Gen. William Shelton, AFSPC's commander, said in the statement. “In the end our objective is continued safe and reliable launch for our nation.”

The GPS IIF line of satellites is being produced by Boeing.