Following successful ADS-B deployment at key sites in the U.S., the FAA gave the go-ahead for the system’s national rollout, with coast-to-coast U.S. coverage forecast in 2013. The agency’s announcement also stated that wide-area multilateration (Wam) “will serve as a backup to ADS-B in the event of a GPS outage in high-value ­airspace.” Puzzlingly, however, the FAA has an expert panel currently examining GPS backups, with its recommendations still to be made, while the ­agency’s final ADS-B rule in May downplayed Wam as a backup candidate. Possibly, this is a pre-emptive FAA strike, following continuing concerns of the Government Accountability Office in September that the Department of Defense cannot be certain the GPS constellation will always provide adequate civil coverage before 2018. The expert panel’s recommended solutions might also not be widely available commercially to counter any early GPS outages.