Definition
A navigation specification, designated by the prefix RNP (for example, RNP 1, RNP 4, RNP APCH), that defines the navigation performance required for aircraft operating along a route, on a procedure, or within a defined airspace. An RNP specification includes a requirement for onboard performance monitoring and alerting, meaning the aircraft's navigation system must continuously check its own accuracy and warn the crew if it is no longer meeting the required performance.
Plain English
A set of rules that says how accurately an aircraft must navigate in a given piece of airspace or on a given procedure, plus a requirement that the aircraft itself watches its own accuracy and alerts the pilot if it falls short.
Context Anchor
Seen in performance-based navigation, instrument procedures, route planning, and aircraft authorization discussions.
Derivation
RNP stands for 'Required Navigation Performance.' The word 'specification' is used here in its formal sense — a written standard that defines what must be met. So an RNP specification is simply a written standard describing the navigation performance an aircraft must achieve.
Why Pilots Care
Meeting the correct RNP Specification gives access to efficient routes and approaches; falling short can limit where the aircraft is allowed to fly.
Intuition Check
Do not read specification as just a description or label. In this context, it means a required standard the operation must meet, including accuracy and onboard warning if performance is not good enough.
Example Sentence 1
The approach into the mountain airport required an RNP specification of RNP 0.3, so only aircraft with approved equipment and crew authorization could fly it.
Example Sentence 2
Before filing the RNAV route the dispatcher confirmed the aircraft met the published RNP Specification for that segment.