Definition
Airborne navigation systems that allow an aircraft to fly any chosen course within the coverage of station-referenced navigation aids, within the limits of self-contained system capability, or a combination of both. Rather than requiring flight directly to or from a ground-based navigation station, RNAV systems compute the aircraft's position from sensor inputs (such as GPS, DME/DME, or inertial reference) and guide the aircraft along a defined path between waypoints stored in the navigation database.
Plain English
RNAV systems let an aircraft fly directly between any two points in space, instead of being tied to flying overhead a ground-based radio beacon. The system figures out where the aircraft is, where the next waypoint is, and gives the pilot or autopilot steering guidance to get there.
Context Anchor
You see this term in instrument flying, especially when loading and flying routes, arrivals, departures, and approaches from the aircraft’s navigation database.
Derivation
RNAV stands for Area Navigation. The word 'area' is the key: instead of navigating along radials emanating from a single ground station (point-to-point), the aircraft can navigate anywhere within an 'area' covered by the underlying signals. This is why the term replaced older route-bound navigation thinking.
Why Pilots Care
RNAV systems allow more direct routes, reduced flight time, and access to procedures that would otherwise be unavailable.
Intuition Check
RNAV does not mean “GPS only.” GPS is one common source of position information, but RNAV is the broader system that guides the aircraft along selected point-to-point paths.
Example Sentence 1
The RNAV system guided the aircraft directly from the departure airport to the arrival fix without overflying any ground-based navaids.
Example Sentence 2
Modern RNAV systems can guide the aircraft to an approach fix that has no ground-based navigation aid nearby.