Definition
A procedure in which the pilot verifies that an RNAV (Area Navigation) system is providing position information within acceptable tolerances before relying on it for navigation. This is typically done by comparing the RNAV-indicated position to a known reference point, such as an airport surveyed location or a designated checkpoint, and confirming the displayed distance and bearing fall within the limits published for that aircraft and equipment.
Plain English
A quick test the pilot does to make sure the aircraft's navigation computer is showing the right position before using it to fly the route.
Context Anchor
Seen in instrument flying before using RNAV guidance for a route segment or instrument procedure, especially before an RNAV approach.
Derivation
RNAV stands for Area Navigation, meaning navigation that lets the aircraft fly a direct path between any two points rather than only between ground-based stations. An accuracy check is simply a test of how close the system's reported position is to the real position.
Why Pilots Care
Ensures the RNAV system meets the required navigation performance so the aircraft remains within protected airspace and the approach or route can be flown safely.
Grounding Statement
The point of the check is simple: confirm the navigation system is trustworthy before letting it guide the airplane.
Intuition Check
Do not assume an RNAV accuracy check means only that the RNAV unit is powered on or that the route is loaded. It means the pilot has verified that the system’s position and guidance are accurate enough to rely on.
Example Sentence 1
Before departing, the pilot performed an RNAV accuracy check by confirming the displayed position matched the surveyed location of the parking ramp.
Example Sentence 2
During the preflight briefing the pilot noted the RNAV accuracy check had already been accomplished at the ramp using the published ground checkpoint.