NATCA Bookshelf

National Office Week in Review: September 12, 2017

A publication of the National Air Traffic Controllers Association

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which the pilot conducts a go - around mitigate the use of less than 50 seconds (e.g. use a technique that does not involve use of TOGA)? If yes, how shor t can the straight segment be? This again point to the need for a data collection effort. To help resolve this question (especially number four ) the Nav WG will get FOQA (track) data from cooperating airline s and MITRE will analyze same. In particular we will look at JFK, ABQ, DCA, BUR, etc. flown in IMC to successful landings. All the operators present agreed to help with the data collection, Mike has the action to coordinate the activity . Barry Miller (AIR - 6B1) suggested another potential data source would be the 2008 AF S - 400 DA - in - a - Turn sim trials. He believes the most benign DA - in - a - Turn profiles demonstrated in the sim trials included completing a turn in the FAS coincident with arri val at the DA (H); and there may be data for an even more benign FAS with a short strai ght segment leading to the DA. Barry will review the FAA documentation of the trials and provide the WG any practical, available data. A - RNP Team Status Mike Cramer (MI TRE) asked the group to join in a brainstorming session to identify history, and possible ways forward to eliminate the bank angle restriction on RF in RNP<1 and the minimum radius of 3 x RNP. Regarding the bank limit, the following discussion points were raised: - The historical reason for the limit was that some aircraft were limited to 20 degrees maximum control authority when coupled to the AP. However, the FAA received to RNP AR ops approval requests from an operator with this limiting aircr aft perfor mance. No other historical reasons seem to exist. - We may need to investigate whether departures might be different from approach limits in some avionics. - FAA restricted bank angle in procedure design to 18 ⁰ ; but, to align the criteria with the new airworthiness requirements (e.g. RNP MASPS and MOPS), a recent update makes the limit 25 ⁰ . - MITRE has done bank limit surveys; this information table should provide a basis for any decision / recommendation. - MITRE and Nav WG should revisit the table with OEMs for accuracy . - Low speeds and altitude limits may apply . - Need to identify any differences between defined arc or flyby turns . - Update for business/GA aircraft e.g., Honeywell NZ FMS . - Current sys tem requirements (DO - 236C and ACs) command bank angles up to 30 ⁰ , supporting procedure design criteria using a max bank of 25 ⁰ , which provides a 5 ⁰ margin for correcting to path. Discussion of the 3xRNP minimum limit on RF radius began with Wes Combs and Gary Petty showing the computational problems with evaluating O EAs for turns where the

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