Preflight RAIM checks for non-WAAS GPS receivers

September 24, 2009

As of Sept. 28, pilots utilizing non-WAAS-equipped IFR GPS units under instrument flight rules (IFR) must perform a Receiver Autonomous Integrity Monitoring (RAIM) check as part of their preflight requirements prior to flying certain routes and procedures.

The routes and procedures affected include:

  • T routes (RNAV routes below 18,000 feet msl)
  • RNAV Obstacle Departure Procedures (ODPs)
  • RNAV Departure Procedures (DPs)
  • RNAV Standard Terminal Arrival Routes (STARs)
  • Q routes (RNAV routes above 18,000 feet msl)

Loss of GPS RNAV instrument approach procedures are not affected by this change because IFR GPS units automatically perform a RAIM check before beginning an approach.

WAAS-equipped GPS receivers do not require a preflight RAIM check. However, pilots must still check WAAS notams to learn of any predicted outages. These notams are not included in a standard briefing and must be requested.

For more information, as well as a list of the units affected, see AOPA’s issue brief.