Radio navaid 'snapshot' a glimpse of tomorrow

 - August 4, 2008, 11:37 AM

At recent public hearings in Washington, D.C., and Albuquerque, N.M., DOD and DOT representatives reviewed the departments’ policies toward the provision of radionavigation services to the U.S. civil user community between now and 2020. The hearings were held to solicit user comments on those policies before publication of this year’s federal radionavigation plan (FRP), which will be available by year-end.

The FRP is produced jointly by the DOD and DOT, and provides a current “snapshot” of how the two departments and their agencies, such as the FAA, Coast Guard, the National Highway Administration and others view the nation’s future navigation needs, and how they intend to meet these needs. In bureaucratic language, the annual FRP is a “living document,” reflecting expected developments in navigation technology, coupled with official perceptions of the likely decline in use of earlier systems and their projected termination dates.

The chart illustrates the departments’ current expectations, which spotlight GPS–augmented by WAAS and LAAS–as the dominant aviation navaid beyond 2013. By that time, the nation’s 1,005 VORs will have dwindled to 471, although signal coverage–based on 75-nm reception range at 5,000 feet–will remain available over most of the continental U.S. NDBs will also have been reduced by more than 50 percent, while only one Category I ILS will operate at those airports currently equipped.

Today’s Category II and III ILS installations however, will remain at least until 2020, perhaps reflecting continuing uncertainty about whether Category II/III LAAS will ever graduate from a research program into an operational system.

Over the years, public attendance at FRP hearings has slowly declined, perhaps due to wide user acceptance of GPS for air, marine and land navigation. At earlier hearings, strong opinions were often expressed by users about the planned demise of favored systems. At this year’s hearings, a major issue raised concerned the future of loran, predicted in the late 1990s to be terminated in 2000, but still operating and being modernized today under congressional fiat, and with its future prospects appearing brighter as a backup/complement to GPS in the potential presence of jamming.

Another possible reason for reduced attendance is that although the FRP is a “snapshot,” its focus has been occasionally blurred in the past. One earlier FRP anticipated Category I via WAAS by 2001, with ILS reductions beginning in 2005 and its complete removal by 2010. An even earlier FRP saw ILS reductions starting in 1998 and completed by 2005 as MLS swept the nation. Operators should therefore regard it as a broad guide to current government thinking, rather than a firm basis for budgeting equipment installation or removal.

Yet for all that, the FRP remains an informative document, including not only implementation and decommissioning forecasts but also extensive descriptive material on radio navaids and other related material.