AOPA yesterday urged the FAA to support the continued operation of the loran navigation system until a permanent backup system for GPS is established. The U.S. Coast Guard plan to decommission the loran system is "premature," AOPA said. "Once gone, loran will no longer be a backup option, and any other suitable aviation alternative would likely be more costly, take longer to implement, and would be the responsibility of the FAA exclusively," AOPA President Phil Boyer told FAA Administrator Marion Blakey. "Let's look before we leap on this issue." Although most GA pilots use VORs as a backup navaid, the FAA is planning to decommission VOR stations, leaving no backup system should there be a major disruption to GPS. Originally developed for military and marine navigation, loran uses a chain of low-frequency, ground-based radio transmitters maintained by the U.S. Coast Guard. AOPA asked the FAA to evaluate the viability of loran as a backup navigation signal that supports RNP 0.3 performance and ADS-B requirements, before proceeding with plans to discontinue it.