Project AS 09/12 - Clarification of RNAV and BARO/VNAV Instrument Procedure Design Criteria
Project Closure Notes
Project closed 14 December 2009
Amended AC 173-4(1) - Instrument Procedures Design Clarification of RNAV and BARO/VNAV Criteria has now been published. AC 173-4 has been amended to correct an error in the formulae located in paragraph 7.2 - Diagram
AC 173-4(0) was published on 8 December 2009.
Application of ICAO instrument procedure design criteria are mandated by CASR Part 173. Certain aspects of RNAV and BARO/VNAV criteria contained in ICAO Doc 8168 (PANS - Aircraft Operations) are unclear. Consequently, application of these criteria attract interpretation that may or may not be accurate.
The criteria that pertain to RNAV are contradictory while those that apply to BARO/VNAV are counter-intuitive. Strict application of the RNAV criteria applicable to segment blending is not possible without choosing between the two ideas that are presented. The BARO/VNAV criteria applicable to the missed approach use factors normally applied to other than the missed approach. Such counter-intuitive operations invite interpretation and are a possible source of errors. The confusion raised by the way the criteria are expressed may result in an inappropriate interpretation with consequent incorrect application.
The risk has been assessed as moderate for both the RNAV and BARO/VNAV issues.
If no action were taken, and an incorrect interpretation crept into the operating practices of a Certified Designer, the consequent procedures would not afford the level of safety expected of them with a resultant increased potential for impact with the ground or obstacles that would grow as that Designer continued to operate.
Develop an Advisory Circular under CASR Part 173 that removes the potential for confusion outlined above.
This project was approved by Peter Boyd, Executive Manager, Standards Development & Future Technology Division on 7 August 2009.
Project Leader: Martin Chalk, Project Officer, Airways & Aerodromes Branch
Project Stakeholder: Peter Cromarty, Executive Manager, Airspace & Aerodrome Regulation Division
Standards Development Program Manager: Nick Fisher
Airspace and Infrastructure Users Group (SCC)
|Consultation updates in 2010|
|Final AC 173-4(1) – Instrument Procedures Design Clarification of RNAV & BARO/VNAV Criteria||This Final AC has been updated and is available on the CASA website.||3 Aug 2010|
|Consultation updates in 2009|
|Project AS 09/12 - Clarification of RNAV and BARO/VNAV Instrument Procedure Design Criteria||
This project is now closed
See project closure notes.
|14 Dec 2009|
|Final AC 173-4(0) – Instrument Procedures Design Clarification of RNAV & BARO/VNAV Criteria||
This Final AC has been published.
|8 Dec 2009|
|Draft AC 173-4(0) - Instrument Procedures Design Clarification of RNAV and BARO/VNAV criteria||Comments closed Monday 26 October 2009.||12 Oct 2009|
|Project AS 09/12 - Clarification of RNAV and BARO/VNAV Instrument Procedure Design Criteria||Project approved.||12 Aug 2009|