"This Doesn't Make Any Sense"

Uh oh. If you've relied on an IFR-certified GPS receiver for flying instrument procedures, the Aircraft Owners and Pilots Association reports you may be in for a rude surprise. The FAA recently changed the rules, and that means several thousand GPS users are, for the moment, out of compliance.

AOPA says the issue came about in March, when the FAA updated avionics compliance tables in Advisory Circular 90-100A and made changes to the Aeronautical Information Manual. It means that up to 26,000 GPS users no longer comply with a 1998 FAA policy that allows GPS to be used in lieu of ADF or DME.

"This doesn't make any sense. In most cases, this is not a safety of flight issue," said Randy Kenagy, AOPA senior director of strategic planning. "Pilots affected will lose access to approaches and published routes unnecessarily."

According to the FAA documents, only three GPS models -- the Garmin 400-, 500-, and G1000-series -- are legal. Other models made by Garmin -- including its new GNS 480 WAAS receiver -- as well as receivers manufactured by Chelton, Honeywell, Northstar, and Trimble are listed as "noncompliant," as seen on the chart below.

It gets worse... as many pilots removed ADF and DME navigation equipment from their aircraft because of the 1996 policy allowing those receivers to be used for instrument approaches. Under the new rules, those pilots will no longer have access to conventional and precision approaches where the equipment is a required element.

Complicating matters further, the older GPS boxes are prohibited from flying RNAV routes and terminal RNAV procedures.

In a letter to the FAA, Kenagy told the agency all IFR-certified systems should still be approved for use in lieu of ADF and DME and for flying T routes and certain departure procedures where pilots manually enter the waypoints.

Except for major metropolitan airports, Kenagy added, the use of older boxes should not be restricted.

FMI: www.faa.gov, www.aopa.org