Area navigation

[1] The acronym RNAV originally stood for "random navigation,"[2] reflecting the initial concept of flexible routing, though the term now refers to a precisely defined and controlled method.

The continuing growth of aviation increases demands on airspace capacity, making area navigation desirable due to its improved operational efficiency.

Such prescriptive requirements resulted in delays to the introduction of new RNAV system capabilities and higher costs for maintaining appropriate certification.

This enables the specification of performance requirements, independent of available equipment capabilities, and is termed performance-based navigation (PBN).

FTE relates to the air crew or autopilot's ability to follow the defined path or track, including any display error (e.g.

However, at the present time, there are no navigation specifications requiring 4-D control, and there is no FTE in the longitudinal dimension.

The along-track accuracy affects position reporting (e.g. "10 NM to ABC") and procedure design (e.g. minimum segment altitudes where the aircraft can begin descent once crossing a fix).

The expression 'X' (where stated) refers to the lateral navigation accuracy in nautical miles, which is expected to be achieved at least 95% of the flight time by the population of aircraft operating within the airspace, route or procedure.

Manual or automated notification of an aircraft's qualification to operate along an air traffic services (ATS) route, on a procedure or in an airspace, is provided to ATC via the flight plan.

[5] This article incorporates public domain material from websites or documents of the Federal Aviation Administration.