Plain English Meaning

The aircraft's navigation system must keep it within three-tenths of a mile of the planned track, and it must warn the pilot if it can't.

Full Definition

A Required Navigation Performance level specifying that the aircraft must be able to remain within 0.3 nautical miles either side of the intended flight path for at least 95% of the flight time, with onboard performance monitoring and alerting if that accuracy cannot be maintained. RNP 0.3 is commonly used for helicopter approach segments and certain low-altitude RNP routes.