A publication of the National Air Traffic Controllers Association
Issue link: http://natca.uberflip.com/i/872987
PARC NAV WG The PARC NAV WG recent ly held a meeting in Seattle, as well as wi th some additional telcons where the main topics of discussions have resolved around the following: RNP AR - 50 second Rule Mike Cramer (MITRE) introduced the discussion, turning to Barry Miller (FAA) for an update on the European perspective and e xamples . This topic is under discussion at the ICAO PBN Study Group as well. Barry noted the following: Airbus does NOT support less than 50 seconds. However, this is not an aircraft requirement but a pilot requirement in their discussions. After the original m inutes were published, Patrice Rouquette of Airbus provided the following expansion of the Airbus position: Patrice: "I think this statement (#1 above) is not reflecting exactly the Airbus position. Indeed, Airbus is not against decreasing the "50s" requ irement, but Airbus states that: For Airbus aircraft without "TOGA to LNAV" option, guidance laws (i.e. aircraft requirement) meet the requirement to "establish a track during go - around that is within 1 degree of the published track following the DA (H)" provided a 50s long straight segment is published before the DA/H (with the entry data I had provided in my previous email) . The ops and human aspects are of paramount importance (i.e. pilot requirement). Therefore, procedure design for "normal" instrumen t approach operations should be based on a sufficient time where the aircraft is established on a constant track prior to DA/H." There are "some" aircraft issues but none reall y require 50 seconds. Not all aircraft have TOGA/LNAV; however, this masks the issues since the go - around function in the aircraft is not necess ary to abandon an RNP AR APCH. That is, some concern exists for pilot spatial disorientation during the transition to landing after completing a turn in the FAS; yet, potentially, use of the go - around function, which may be combined with the auto - throttle or pilot power selection of max climb thrust, can be a real source of pilot spatial disorientation. Most ops manuals for RNP approach ops address this issue and offer an alternative to abando n an instrument approach (e.g. use of flight - level change in lieu of the go - around function). AIR supports 15 seconds (1 to ½ mile before DA) when pilot procedures and training address the means to abandon an RNP AR IAP in li eu of using the TOGA function. This should mitigate the Airbus concern. The ICAO PBN Study Group also discussed this issue as part of their coordination with the ICAO Instrument Flight Procedures Panel (IFPP) New Criteria WG. Currently, the PBN SG plenary believes data should support the application of less than a 50 - second straight segment in an RNBP AR IAP's FAS. An open question appears to: What is an acceptable length of a straight segment leading to the DA (H), which allows the pilot - flying to successfully transition t o land? To answer this question, an organization needs to develop test scenarios for a data collection ef fort resulting in the answer. Another question is: Can altering the means by