Definition
An in-flight loss or malfunction of one or more navigation receivers (such as VOR, ILS, GPS, or DME) that prevents the pilot from determining position or tracking a course by normal electronic means. Under instrument flight rules, the pilot must notify ATC, use any remaining navigation equipment, and may request radar vectors, an alternate routing, or a different approach.
Plain English
Your navigation equipment stops working properly, so you can no longer rely on it to tell you where you are or to follow your planned route. You tell ATC, switch to whatever still works, and get help finding your way.
Context Anchor
Encountered during instrument flight when a pilot is using aircraft navigation equipment to follow a route, identify position, or fly an instrument approach.
Derivation
Navigation comes from older words meaning to steer or travel by ship. Radio comes from a word meaning a ray or beam. Together, the phrase points to steering or finding your way by signals sent through the air.
Why Pilots Care
It removes primary navigation references and requires immediate use of backup methods or ATC assistance to avoid loss of situational awareness.
Intuition Check
Do not assume navigation radio failure means every radio in the aircraft has failed. It usually means the navigation receiver or navigation indication is unusable; voice communication may still work.
Example Sentence 1
After the VOR receiver went dead halfway through the en route segment, the pilot declared a navigation radio failure and accepted radar vectors to the nearest suitable airport.
Example Sentence 2
The crew responded to navigation radio failure by switching to dead-reckoning and monitoring backup instruments.