The US Air Force (USAF) has convened an accident investigation board (AIB) to examine an incidence of lower-than-expected thrust from the 4 October launch of a GPS satellite.

While the United Launch Alliance (ULA) Delta IV launch from Kennedy Space Center (KSC), Florida, successfully placed the Boeing GPS-IIF satellite into the correct orbit, the Rocketdyne RL-10 upper stage produced less thrust than anticipated.

Details of the incident are not immediately available, but the onboard computer was able to compensate for the reduced thrust and place the satellite into orbit.

Rocketdyne, which manufactures the RL-10 engine, referred comment to the USAF. The USAF was not immediately available for comment.

While the launch successfully placed the satellite into its correct orbit and telemetry was successfully transmitted, convening an accident investigation board for a successful launch is highly unusual. AIBs are generally convened for so-called Class A mishaps, involving over $2 million in damages or resulting in serious injuries or deaths, neither of which were known to have occurred during the 4 October launch.

The launch of an Atlas V carrying the Boeing X-37, the next scheduled launch to use the RL-10, has been placed on hold as investigators determine the craft's safety.

Source: Flight International