Definition
Flight paths that follow a defined arc or curve between waypoints rather than a straight line, made possible by Required Navigation Performance (RNP) procedures using a fixed-radius turn known as a Radius-to-Fix (RF) leg. The aircraft's flight management system flies the curve precisely along a published radius, allowing predictable, repeatable turns within tightly defined airspace.
Plain English
Instead of flying straight, then turning, then flying straight again, the aircraft follows a smooth curved path along a published arc. The autopilot tracks that curve accurately enough that the airplane stays within a narrow protected corridor the whole way around.
Context Anchor
Seen in RNP instrument procedures, especially where the published path must curve around terrain, obstacles, restricted areas, or traffic flows.
Derivation
“Curved” comes from the idea of something bent rather than straight. “Track” originally means a path or trail; in aviation, it means the airplane’s actual path over the ground. Together, the term points to a bent path the aircraft is expected to follow across the ground.
Why Pilots Care
Allows instrument procedures around terrain or obstacles where straight segments would not work.
Analogy
Think of it like staying in a marked lane through a highway curve. The goal is not just to end up at the next point, but to stay on the intended curved path between points.
Intuition Check
Do not read “curved flight tracks” as any normal turn the pilot happens to make. Here it means a specific published ground path the aircraft is expected to follow.
Example Sentence 1
The RNP approach into the valley uses a curved flight track to keep the aircraft clear of the ridgeline on the south side.
Example Sentence 2
The aircraft maintained required performance while flying the curved flight tracks on the arrival.