The U.S. Air Force has ruled that the first Falcon 9 v1.1 flight conducted last fall does count as one of three required for Space Exploration Technologies (SpaceX) to be certified to compete for boosting U.S national security payloads into orbit, as the upstart company works to take on the United Launch Alliance (ULA) monopoly.

Lt. Gen. Ellen Pawlikowski, commander of the Air Force Space and Missile systems Center, determined that the Sept. 29 launch would support certification despite a malfunction in an attempted upper-stage engine restart. Her decision was announced Feb. 24.

An embarrassing oversight by SpaceX prompted the mishap; the upper-stage restart was not required for the mission to deliver a Canadian satellite into its orbit but was designed as a risk-reduction exercise. Such a restart is critical for boosting payloads into the orbits most desired by the U.S. Air Force, however.

But fluid lines froze in the upper stage because SpaceX neglected to encase them in insulation for the launch. The shortcoming was not detected on the ground as testing was conducted in ambient air, not in temperatures representative of the space environment.

The fix will add insulation to the system, said company spokeswoman Emily Shanklin. The restart was successfully executed to deliver the Falcon 9 v1.1’s second payload, the SES-8 communications satellite, into geosynchronous orbit Dec. 3.

Full certification requires three successful flights of a common configuration, two of which must be consecutive. The company also must pass rigorous technical audits and process validation exercises.

These criteria were jointly signed by the company and the Air Force in June 2013.

Scott Correll, who retired as the Air Force’s program executive officer for launch, said in November he expects that the soonest SpaceX can be certified and compete for national security launch work is 2015.

The Air Force inked a deal in December with ULA for the purchase of up to 50 rocket cores, 14 of which will be open for competition in the coming years.