Overview. Waypoint classificationsWaypoint namingProcedure namingIntercepting and following a VOR radialStep-down fixes, VNAV and other altitude restrictions Coding departuresDesigning for en-route turns in terminal airspaceSpeed limitsConditional clearancesProcedure altitudesRecommended navaidsRho/thetaFACFsCF for ILS transitionCo-located VOR/DMEs.
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1. Specific Issues
3. Waypoint Classification/1 Waypoints can be classified as en-route (E) or terminal (T).
En route waypoints:
Published to nearest second (ICAO Annex 15)
Uniquely named. (ICAO Annex 11)
Published to nearest 1/10 second. (ICAO Annex 15)
Different naming convention. (PANSOPS & EUROCONTROL)
Classification not clearly stated in AIPs.
No industry standard in waypoint classification:
Waypoints in AIP are E, waypoints created by datahouse are T.
Waypoints with 5LNC are E, all other waypoints are T.
At the discretion of the coder.
Pilot can access and use any waypoint regardless of its classification or its associated airport.
Waypoint associated with airport to deal with the many instances of duplicate names e.g. CF04, CF05..
4. Waypoint Classification/2 Designate which are terminal to ensure 1/10 second publication resolution.
Designate which are en-route to ensure availability to pilot.
Waypoint may be en-route and terminal.
Hence AIP should designate ‘E’ waypoints, ‘T’ waypoints and ‘E&T’ waypoints
ICAO and Industry requirement.
5. Waypoint Naming/1 Significant points
identified by co-located navaid or by unique five-letter pronounceable “name-code” (5LNC). (ICAO)
Some waypoints in the terminal area used for vectoring for sequencing and must be easy to enter in an RNAV system.
5LNCs not appropriate for this.
Proceed direct ALECS (or ALEKX, ALECS, ALECX, ALLEX, ALIKS, ALIKX, ALICX, ALLIX, ALYKS, ALYKX, ALYCS, ALYCX, ALLYX).
Concept of strategic and tactical waypoints (EUROCONTROL)
6. Waypoint Naming/2 Strategic: is a waypoint in the terminal area which is:
Of such significance to the ATS provider that it must be easily remembered and stand out on any display, or
Used as an ‘activation point’ to generate a message between computer systems when an aircraft passes it.
Strategic waypoints are identified with 5LNCs unless they are co-located with a navaid, when the 3 letter navaid ID is used.
7. Waypoint Naming/3 Tactical: a waypoint which is defined solely for use in the specific terminal area and has not been designated a strategic waypoint.
Identified as AAXNN, where:
AA - the last two characters of the aerodrome location indicator;
X - a numeric code from 0 to 9 (N, E, W and S may be used instead if a State has a requirement for quadrantal information)
NN - a numeric code from 00 to 99.
EUROCONTROL Guidance iaw PANSOPS
8. Waypoint Naming/4 Exceptions:
If co-located with a navaid, the navaid three letter identifier is used.
If co-located with the runway threshold, an identifier in the format RWNNA is used, where:
NN - a numeric code from 01 to 36 and
A is an optional alphabetic code of ‘L’, ’C’ or ‘R’.
If designated by the ATS provider as a Strategic TMA Waypoint, the 5LNC is used
9. Procedure Naming/1 Annex 11:
The system of designators shall:
a) permit the identification of each route in a simple and unambiguous manner;
b) make a clear distinction between:
— departure routes and arrival routes;
— departure or arrival routes and other ATS routes;
— routes requiring navigation by reference to ground-based radio aids or self-contained airborne aids, and routes requiring navigation by visual reference to the ground;
c) be compatible with ATS and aircraft data processing and display requirements;
d) be of utmost brevity in its operational application;
e) avoid redundancy;
f) provide sufficient possibility for extension to cater for any future requirements without the need for fundamental changes.
10. Procedure Naming/2 The coded designator of a standard departure or arrival route shall consist of:
a) the coded designator or name-code of the significant point where a standard departure route terminates or a standard arrival route begins; followed by
b) a validity indicator; followed by
c) a route indicator, where required; followed by
The validity indicator shall be a number from 1 to 9.
The route indicator shall be one letter of the alphabet. The letters “I” and “O” shall not be used.
Limitations in the display equipment on board aircraft may require shortening of the basic indicator, if that indicator is a five-letter name-code, e.g. KODAP. The manner in which such an indicator is shortened is left to the discretion of operators.
11. Procedure Naming/3 What if two SIDs/STARs to/from same runway use same significant point for naming?
The rule says to use different route indicators.
However, experience shows that pilots get confused with similar sounding names (e.g. ABEN2Q and ABEN2R)
Some States use a different solution - create a new waypoint 3-5NM prior to the common end/start point; name one procedure using the new waypoint.
13. Intercepting and Following a VOR Radial Why the question?
This is an issue of coding a conventional procedure - should not really be in the procedure designer domain!!
However, worth knowing:
that datahouses may use different methods to code this.
this is not an RNAV coding solution.
14. Step-down Fixes and Other Altitude Restrictions/1 General Rules:
Any altitude restriction MUST be associated with a waypoint if it is to be coded.
Time-limited restrictions (e.g night time only) or ‘ATC discretion’ restrictions are never coded.
Try not to code an altitude restriction on the last waypoint of an approach transition (Requirement of some avionics systems)
Some avionics systems require an altitude restriction associated with a waypoint if a speed restriction is to be processed.
15. Step-down Fixes and Other Altitude Restrictions/2 Step down fixes – rules?
VNAV Issues – presentation by Yves Coutier
16. Coding Departures Presentation by Yves Coutier
Presentation on coding initial turns
17. Designing for En-route Turns in Terminal Airspace Presentation by Yves Coutier
18. Speed Limits Speed restrictions must be associated with waypoints.
SLPs based on DME distances are:
not coded for RNAV procedures by one datahouse
coded as FD by another datahouse
coded at a CNF by the third datahouse
Speed restrictions apply up to the waypoint on SIDs - to keep speed down throughout a turn, speed restriction must apply until aircraft is established on next track, i.e. beyond the turn waypoint.
Speed restrictions apply from the waypoint on STARs/APPs.
Some avionics cannot apply speed restrictions without an accompanying altitude restriction.
19. Conditional Clearances Procedures that are conditional on ATC or time and procedure restrictions/alleviations that are conditional on ATC or time are not coded in the airborne database.
20. Procedure Altitudes PANS-OPS Amendment 12 introduced the procedure altitude - is it coded?.
21. Recommended Navaids Required by some path terminators (CF, FA & FM)
Used to source magnetic variation for that leg on SIDs and STARs (Station declination = magnetic variation)
If the recommended navaid includes a DME component, one manufacturer includes that DME in its “top ten” list for scanning purposes.
22. Rho/Theta Rho - distance from navaid to fix
Theta – magnetic bearing from navaid to fix.
Why are they needed?
23. Final Approach Course Fixes Transitions/STARs link to Approach procedures.
Existing non-precision Approach procedures already coded in the database.
Final Approach Track of NPA usually defined by FACF and MAPt.
New RNAV STAR/transition therefore finishes at the existing FACF in airborne database.
Exact location and name of FACF varies from Datahouse to Datahouse.
24. CF for ILS Transition Certain avionics require CF coding on the leg that intercepts the localiser.
Others use TF for the same purpose.
States publishing coding requirements for transitions to ILS approaches should allow the final transition leg that intercepts the ILS to be coded CF or TF.
25. Co-located VOR/DMEs Where a DME is co-located with a VOR, and its co-ordinates are less that 0.1 minute different in both latitude and longitude, it is assumed to have the same co-ordinates in the navigation database.
Otherwise a flag is set to indicate a non co-located DME and the DME co-ordinates are included in the navaid record.
States providing DME/DME infrastructure should ensure that the actual DME co-ordinates are published in the AIP, even when a non co-incident DME is described as co-located.