Air Force officials are criticizing as "overly pessimistic," a Government Accountability Office report that calls into question the Air Force's ability to maintain a minimum number of healthy Global Positioning Satellites in orbit.

The GAO report drew attention to a tight timeframe the Air Force has given contractor Lockheed Martin to construct the first of the GPS III satellites--72 months--and speculated that the ground control segment could run behind schedule, throwing into doubt Air Force plans to launch a number of GPS III satellites in quick secession.

In an hour-long Sept. 24 phone call with reporters, Col. David Buckman, Air Force Space Command lead for positional navigation and timing, said he doesn't dispute the facts of the GAO report.

"The problem is that we think it draws overly pessimistic conclusions based on those facts," he said.

The 72 months given to Lockheed Martin to build the first GPS III satellite is enough despite the fact that the original schedule called for 84 months, said Col. Bernard Gruber, commander of the GPS wing at the Air Force Space and Missile Systems Center.

The Air Force has taken a "back to basics" approach to building GPS satellites and the GPS IIIA program is now two months ahead of schedule following its completion of its critical design review August 19, Air Force officials said.

Moreover, even if the first GPS III satellite were to fall behind schedule by a year, it would not cause the GPS constellation to drop below 24 satellites, the minimum number required to ensure signal strength and accuracy, Gruber said. A delay of two years would have an impact, but such a delay is unlikely, he added.

The GAO report points out that most users would continue to receive GPS signals even if the number were to dip below 24, although accuracy and availability "could diminish in some locations for brief periods."

The GAO may have drawn its conclusions based on the past performance of the GPS program, said Buckman. The first of the GPS IIF satellites launched May 27 after a delay of three and a half years.  

"There's a tendency in the report to almost take too much from the past and apply that to what we're doing in the present and the future on GPS," Buckman said.

For more:
- listen to the press call with Col. David Buckman and Col. Bernard Gruber
- read an Air Force Space Command Q&A related to the GAO report
- download the report, GAO- 10-636 (.pdf)

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