If RAIM capability is lost, what action should a pilot take?

• A. Continue GPS as primary and ignore
• B. Begin using an alternate navigation method and continue monitoring GPS
• C. Turn off GPS and land immediately
• D. Reboot the GPS and resume

Answer: (B)

RAIM provides integrity checks for GPS signals, ensuring the position and guidance you’re using are trustworthy. If RAIM capability is lost, you can’t rely on GPS as your primary navigation source because its accuracy and reliability can no longer be guaranteed. The right course is to begin using an alternate navigation method (such as VOR/DME, NDB, or dead reckoning/inertial navigation as available) and to keep monitoring GPS for restoration. This preserves safety by not trusting faulty GPS data while you maintain situational awareness with backup means. Rebooting the GPS or turning it off and landing immediately aren’t necessary actions unless you have an immediate emergency; continuing to rely on GPS without RAIM is not advisable, and switching to backup nav while monitoring GPS gives you a valid path back to GPS guidance when integrity returns.