Plain English Meaning
A standard that says how accurately an aircraft must be able to navigate on a given route or procedure, with the aircraft itself checking its own accuracy and telling the pilot if it falls short.
Full Definition
A type of performance-based navigation (PBN) that specifies a required level of navigation accuracy, expressed in nautical miles, that an aircraft must maintain along a route, procedure, or in a defined airspace, and which includes onboard performance monitoring and alerting. The aircraft's navigation system must continuously verify it is meeting the required accuracy and warn the crew if it is not.