Home' RTCA Documents for Review : DO-201B User Requirements for Navigation Data Contents ED-77A/DO-201BforOpenConsultation/FRAC
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local magnetic survey, it is the variation used in establishing all non-VOR magnetic
bearings/courses in the area such as localizer courses, NDB bearings, runway bearing,
etc. Because the actual magnetic variation changes continuously, all related values
should [NAV-D007] be changed.
PBN Approach Procedure Application
Preferred PBN leg types described in Section 2.2.6 .1 are defined so that magnetic
variation is not a factor in establishing the ground track. Non-preferred leg types that
follow a magnetic track to or from a fix are affected by magnetic variation errors. RNAV
magnetic tracks reference the airport magnetic variation. As the magnetic field drifts, the
published airport magnetic variation and RNAV magnetic tracks should [NAV-D008] be
Commentary: The track of a geodesic route changes along its path. This effect is more
noticeable at high latitudes and on long legs. The airborne navigation equipment’s
desired track is computed real time while traveling along the geodesic route, but the
published track is one numeric value. These factors may contribute to minor displayed
magnetic track differences, while the guidance, cross track computation and RNP
capability are unaffected.
STANDARD FOR NAMES AND IDENTIFIERS
Aeronautical data elements such as fixes, navaids, aerodromes, and ATS routes
should [NAV-D009] be named or identified using ICAO Standards and recommended
ICAO Annex 11 (Air Traffic Services) defines the international standards for coded
designators of navaids, waypoints, ATS Routes, Standard Instrument Arrivals Routes,
and Standard Instrument Departures.
ICAO Annex 15 (Aeronautical Information Services) describes publishing requirements
for the AIP. As for naming of aeronautical navigation elements, it refers to Annex 11 and
emphasises the importance of correctly applying those naming conventions.
ARINC 424 (Navigation System Data Base Standard) is an international industry
standard that defines requirements for the preparation and transmission of data for
assembly of airborne navigation system databases.
Chapter 7 of the ARINC 424 document establishes the coding rules for identifiers and
name fields when government source does not provide these identifiers or names within
the rules established by ICAO Annex 11.
The application of name and identifier conventions, among other things, ensures a
common language and distinct communication between the pilot and Air Traffic Control,
precludes pilots from mis-selecting fixes from a navigation database or mis-tuning
navaids in an area where two or more navaids have the same frequency or identifier.
Naming Using the ICAO Standard
Naming of Fixes
ICAO Annex 11, Appendix 2 details requirements for the naming and identification of
significant points (fixes).
ICAO specifies that significant points not marked by the site of a radio navigation aid be
assigned a unique, five letter pronounceable name. In line with ICAO SARPs, computer-
based navigation systems were designed to accept a five-character name. It is
especially important that compulsory reporting points and “on-request” reporting points
be named by a civil aviation authority with a unique, five-alpha-character,
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