Definition
A specified level of navigation accuracy, expressed as a number in nautical miles, that an aircraft must be able to maintain along its flight path for at least 95% of the flight time in order to operate in a particular airspace, route, or procedure. For example, RNP 1 requires the aircraft to stay within 1 nautical mile of the intended track 95% of the time.
Plain English
It is a rule that says how accurately an aircraft must be able to navigate to be allowed in a certain piece of airspace or to fly a certain route. The number tells you how close to the planned track the aircraft has to stay.
Context Anchor
Seen on instrument procedures, route requirements, aircraft equipment approvals, and airspace rules that specify what navigation capability is required before a pilot may use that route or procedure.
Derivation
Required' means it must be met to operate there. 'Navigation Performance' refers to how accurately the aircraft can know and follow its position. The 'Level or Type' is the specific value assigned, like RNP 0.3 for an approach or RNP 10 for some oceanic airspace.
Why Pilots Care
Determines whether the aircraft's avionics are approved for the route or approach and directly affects flight planning and safety margins.
Analogy
Think of it like a road lane with a stated maximum allowed drift. A narrow lane requires more precise steering than a wide lane; a smaller RNP number requires more precise navigation than a larger one.
Intuition Check
Do not read “performance” here as general aircraft performance, such as climb rate or engine power. Here it means navigation accuracy: how closely the aircraft can keep to the intended path and warn the pilot if it cannot.
Example Sentence 1
The approach into that mountain airport requires RNP 0.3, so only properly equipped and approved aircraft can fly it.
Example Sentence 2
Some airways allow any RNP type while others restrict operations to RNP 1 or better.