A publication of the National Air Traffic Controllers Association
Issue link: http://natca.uberflip.com/i/961329
reasons that the multiple IFs should not be allowed for A ‐ RNP as well as for RNP AR. Mike has the action to draft a recommendation for review in our next telecon. Recommendation Problem Statement Current criteria does not allow the use of multiple intermediate fixes (segments) for procedures other than RNP AR, such as A ‐ RNP instrument approach procedures see Order 8260.19H paragraph 8 ‐ 2 ‐ 2. c. Multiple fixes (segments) are allowed in RNP AR procedures per Order 8260 - - ‐ 58A based in part on the PARC RNP Charting WG recommendation (12 March 2010) which was responding to AC F 09 ‐ 02 ‐ 220. The PARC work was taken to the Aeronautical Charting Forum at ACF 10 ‐ 02. It specifically recommended limiting multiple IFs to RNP AR, but raised the question of allowing them for other procedure types, recommending that the issue should be rev isited after m ore experience had been gained. While discussing the possibility of replacing some RNP AR procedures where A ‐ RNP should suffice, the Navigation WG realized that this would be an issue. Using A ‐ RNP instead of RNP AR for procedures only needin g the RF and RNP values down to 0.3 NM to expand participation to more aircraft lead the WG to an examination of the Denver RNP AR procedures that meet these criteria. The Denver procedures, however, make extensive use of multiple intermediate fixes and segments for implementation, which is not allowed except for RNP AR. In 2017, the WG added this issue to the work plan for 2018. After review of the original ACF material and subsequent discussion the WG could find no differences between RNP AR and A ‐ RNP operations that would drive a restriction on use of multiple IFs in A ‐ RNP procedures. Given that current criteria don't mention use of multiple IFs outside of RNP AR, and that operations and equipment are very similar between AR and ARNP, the WG concluded that multiple IFs for A ‐ RNP is both feasible and practical to gain the benefit of expanding fleet use through A ‐ RNP in many cases. The Navigation WG recommends that the FAA revise criteria to allow the use of multiple intermediate fixes (segments) in IAP s requiring the A ‐ RNP NavSpec in the same manner as implemented for RNP AR (down to RNP 0.3). Intermediate Segment Length Work Session The WG had reached consensus in the last virtual meeting that the current requirement text does not really capture the necessary intent It limits the length of the intermediate segment to 15 NM, when in fact what is desired is that operation on the intermediate should remain within 15 NM of the altimetry source to avoid temperature - driven altimeter errors that might come t oo close to the 500' ROC that is applied in the intermediate. The group all agreed that limiting the length of the segment would accomplish this for segments aligning with the final, however in many applications the intermediate needs to be much longer to avoid terrain or traffic, but it is all still close to the airport. The group drafted a recommendation during the meeting which Mike will formalize and prepare for SG review. New Business