Navigation applications can be viewed from different perspectives, for example by flight phase which refers to applications in en-route, terminal, approach and landing.
Navigation applications are essentially used for three purposes:
- to separate aircraft;
- avoid obstacles;
- facilitate access to airports.
In general terms it can be said that the separation between aircraft (including the spacing between ATS routes) is determined primarily, but not exclusively, by aircraft navigation performance (though the availability of radar can help reduce route spacing).
Similarly, how close procedures can be placed to obstacles is also dependent on an aircraft’s navigation performance. Aircraft’s navigation performance was initially exclusively dependant on the ground-based conventional navigational aid used for navigation onboard the aircraft (e.g. VOR, DME, NDB, ILS, etc.).
Now with the wider use of Global Navigation Satellite Systems (GNSS) and the availability of RNAV systems on all types of aircraft, navigation performance can be defined in a generic way allowing any combination of systems to meet the requirements. This is the ambition of the PBN manual introducing PBN applications as a replacement to applications based on conventional navaids.
Airport access and landing also depend on navigation with a landing system which provides guidance towards the runway. Whilst Precision landing has traditionally been associated with instrument- and/or microwave landing systems (ILS and MLS), increasing use is being made of satellite technologies for landing. The GBAS (Ground Based Augmentation System) landing system (GLS) supports precision approach and landing operations and is aimed at replacing ILS. GNSS is also used to support RNP approach operations (which are PBN applications) with the aim of replacing conventional non-precision approaches, to propose approach with vertical guidance other than precision landing (APV) and improve airport access and safety.
Our contribution to navigation applications
Current and future navigation applications are being addressed in the context of the Navigation Steering Group (NSG). Two sub-groups of the NSG called the Landing and Take-Off (LATO) Focus Group and the RNAV Approach implementation Support Group (RAiSG) address in more detail precision landing and PBN final approaches respectively.
We also contribute to a number of SESAR and Single Sky projects.