X-Range Navigation
X-Range Navigation in aviation, often referring to Area Navigation (RNAV), is a system that allows aircraft to fly on desired flight paths within the coverage of navigation aids. This method was developed in the 1960s in the United States and saw published routes in the 1970s. The "X" value indicates the lateral navigation accuracy expected, typically within a certain nautical mile range.
Historical Development
Before RNAV, aviation relied on methods like pilotage (using visual landmarks), dead reckoning (calculating position from known direction and distance), and radio navigation using radio aids.
The first radio navigation systems included radio direction finding (RDF), which used radio signals to determine direction to a station.
Low-Frequency Radio Range (LFR)
A significant system, LFR, used low and medium-frequency radio signals to provide navigation guidance, especially during instrument flying in the 1930s and 1940s. It was commonly known as "the range".
World War II and Beyond
During World War II, systems like GEE, based on measuring time delays between radio signals, were developed for medium-range navigation.
RNAV's Rise
RNAV, also known as area navigation, emerged as a more precise and versatile navigation method, enabling aircraft to fly on any desired course.
How RNAV Works
- RNAV uses navigation aids like VOR (VHF Omnidirectional Range), NDB (Non-Directional Beacon), and later, GPS.
- Aircraft equipped with RNAV systems can calculate their position relative to these aids and deviate as needed to follow a desired route.
- The "X" in X-Range Navigation refers to the expected lateral accuracy of the aircraft's position, usually within a certain nautical mile radius.
In essence, X-Range Navigation, or RNAV, represents a significant advancement in aviation navigation, allowing for more flexibility and precision in flight planning and execution.
