FAA Grants Safety Waiver to SpaceX for West Coast Launch

The FAA’s Office of Commercial Space Transportation (AST) has granted SpaceX a waiver related to one of three safety factors for its first west coast launch next month.

SpaceX plans to launch a new version of its Falcon 9 rocket, the Falcon 9 v1.1, in September from Vandenberg Air Force Base.  The payload is a Canadian scientific and research satellite, Cassiope, which is headed to a polar orbit, plus five secondary payloads.

According to the FAA’s decision, published in today’s Federal Register, launches must meet specific safety probability thresholds for three factors:  impacting inert and impacting explosive debris, toxic release, and far field blast overpressure.   It is the third that is problematical for this launch.

The total expected average number of casualties (Ec) for any of the three factors is not supposed to exceed 0.00003.  When combined, the total risk is not supposed to exceed 0.0001 Ec.

The Falcon 9 v1.1 launch is expected to exceed the 0.00003 level for far field blast overpressure because it is a new launch vehicle and because weather conditions that exacerbate that phenomenon are common near Vandenberg in September.  The specific weather condition is an inversion layer that reflects shock waves, increasing the risk of damages from an explosion.

However, the risk for the other two factors (debris and toxic release) is rated very low.  When combined, the FAA says the total risk will be under the 0.0001 threshold “approximately forty percent of the time during September” and it therefore approved the waiver request.   If the collective risk were to exceed the 0.0001 Ec threshold “SpaceX would not launch until conditions improved sufficiently for the risk of the launch to satisfy the limits allowed by the waiver.”

The FAA notes that it granted a waiver for an April 2012 SpaceX launch from Cape Canaveral when the risk from debris exceeded the nominal value, and the Air Force waived a requirement for a Titan IV launch in 2005.

The FAA ruling also notes that the Air Force calculates the “overall failure probability” for the Falcon 9 v.1.1 at “nearly fifty percent for each of the first two launches.”