Definition
An air traffic control separation standard that allows controllers to apply reduced separation between aircraft when each aircraft is flying an Authorization Required (AR) Required Navigation Performance approach and is confirmed to be tracking the published path within its specified lateral performance limits. Once an aircraft is established on the RNP procedure, its flight path is considered predictable enough to permit closer spacing with other suitably equipped traffic.
Plain English
It means the aircraft is locked onto a precise GPS-based approach path so accurately that controllers can safely place other aircraft closer to it than they normally would.
Context Anchor
Seen in instrument approach and ATC discussions involving RNP approaches, especially where the published approach path includes turns before final.
Derivation
Established here means firmly settled on the published track, not just heading toward it. RNP stands for Required Navigation Performance, a standard that specifies how accurately an aircraft must hold its path. Knowing the word established carries the sense of confirmed and stable helps explain why this status unlocks tighter spacing.
Why Pilots Care
Confirms the aircraft meets the performance needed to continue the approach safely and reach the published minima.
Intuition Check
Established does not mean simply cleared for the approach or close to the course. Here it means the aircraft is actually tracking the required RNP path within the allowed limits.
Example Sentence 1
Once the crew confirmed they were established on RNP, the controller cleared a second aircraft for a parallel approach.
Example Sentence 2
After the turn to final, the crew confirmed the aircraft was established on RNP before beginning the descent.