Plain English Meaning

How close the aircraft really is to where its navigation system says it is. The tighter the required accuracy, the smaller the allowable error between actual position and displayed position.

Full Definition

A measure of how closely an aircraft's actual position matches the position indicated by its navigation system, expressed as a maximum allowable error (in nautical miles) that the system must stay within for a specified percentage of flight time, typically 95 percent. In RNP operations, the required navigational accuracy is defined by the RNP value for that route or procedure (e.g., RNP 1 means the aircraft must remain within 1 NM of the intended path 95 percent of the time).

Context Anchor

Seen in instrument flying, especially when reading about , requirements, and whether an aircraft’s is suitable for a route or approach.