En-route navigation
En-route navigation
Required track accuracy and system functionalities are detailed in each Navigation Specification.
Over the next decade, the European mandate will require:
En-route segments
Aircraft fly from waypoint to waypoint (sometimes referred to as flying 'To-To-To').
The turn performance of the aircraft is determined by the waypoint definition (flyover, fly-by or FRT) as well as altitude, aircraft speed and wind.
Turn performance varies depending on altitude, angle of turn, wind and speed. Systems having Fixed Radius Transiton (FRT) capability (an optional functionality to support en-route RNP Navigation Specifications) will provide better and more repeatable turn performance.
To guarantee predictable and highly repeatable flightpaths when turning, FRTs can be used.
22.5NM above FL200,
15NM below FL190.
It should be noted that the FRT functionality is only available on modern aircraft and not all aircraft can execute this type of turn.
There are extra functionality options, such as FRT and Baro VNAV, which any State or Region may choose to mandate for certain Navigation Specifications pertinent to the en-route phases of flight.
FRT Option - Area of applicability
For access into oceanic/remote continental airspace some Navigation Specifications can only meet this with ‘high continuity’.
These options are detailed either in the Navigation Specification, or the Appendices in Part C of Volume II of the PBN Manual.
They apply almost exclusively to RNP Navigation Specifications.