ICAO CIR350:2020

The material in this circular is limited to the application of minimum divergence angles of RNAV 1 instrument flight procedures used in an air traffic services (ATS) surveillance environment by aircraft that depart from parallel runways with minimum centerline spacing of 760 m (2 500 feet).

PURPOSE

This circular provides guidelines and supporting material for the implementation of performance-based navigation (PBN) departure procedures with reduced divergence. The reduced divergence is intended for use with aircraft flying area navigation (RNAV) departure procedures whose courses diverge immediately after departure. The material modifies provisions previously included in Chapter 6 of the Procedures for Air Navigation Services — Air Traffic Management (PANS-ATM, Doc 4444).

The material also modifies provisions previously included in Chapter 6 of the Procedures for Air Navigation Services — Aircraft Operations (PANS-OPS, Doc 8168) and Chapter 3 of the Manual on Simultaneous Operations on Parallel or Near-Parallel Instrument Runways (SOIR, Doc 9643).

The continuing growth of aviation raises demands on airport departure capacity and increases noise emissions from aircraft operating in the vicinity of airports. Where possible, the use of diverging departure operations has improved operational efficiencies to accommodate increasing demands. Where operational constraints (e.g., noise constraints) preclude or limit conducting diverging departure operations with the current minimum divergence requirement of 15 degrees, PBN-enabled reduced divergence departures may enable needed gains in operational efficiencies. The procedures with reduced divergence utilize existing aircraft equipage and air traffic control (ATC) capabilities to enable (or increase) beneficial uses of diverging departure operations.

As outlined in the 2013-2028 Global Air Navigation Plan (Doc 9750), implementation of PBN in terminal airspace is recognized as a key enabler for advanced terminal operations. Various Separation and Airspace Safety Panel (SASP) activities currently support the development and amendment of terminal separation Standards.

The SASP’s work on reduced divergence requirements was based on research previously conducted by The MITRE Corporation’s Center for Advanced Aviation System Development. Initially presented at the nineteenth SASP Working Group of the Whole Meeting¹ (Montréal, Canada, 23 May to 3 June 2011), the reduced divergence requirements were based on the application of the equivalent lateral spacing operation (ELSO) concept. For variable runway layout geometries, application of the concept enables reduced divergence angles that provide lateral spacing between diverging flight paths of PBN departures in a manner equivalent to the spacing observed in conventional departure operations conducted using the minimum requirement (15 degrees) of the conventionally applicable divergence Standard.

Further work on the subject, particularly related to assessing the safety of the proposed operations and the adoption of a reduced divergence Standard, was presented at the SASP’s twenty-first ² (Seattle, United States, 29 October to 9 November 2012), twenty-second ³ (Montréal, Canada, 13 to 24 May 2013), and twenty-third ⁴

(New Delhi, India, 11 to 22 November 2013) Working Group of the Whole meetings. Beginning in November 2013, the work considered a single divergence requirement of 10 degrees for adoption in PANS-ATM.

1. SASP-WG/WHL/19-IP/2, Reduced Divergence Departures — A Standard for Equivalent Lateral Spacing Operations

2. SASP-WG/WHL/21-WP/19, Concept, Application, and Benefits of Equivalent Lateral Spacing Operation (ELSO) Departures and SASP-WG/WHL/21-FL/14, Collision Risk Calculations in Support of WP/19 – ELSO Trial

3. SASP-WG/WHL/22-WP/06, Evaluation of PBN-Enabled Reduced Divergence for Departures

4. SASP-WG/WHL/23-IP/05, Engineering Analysis for Reduced-Divergence Departures and SASP-WG/WHL/23-IP/05, Engineering Analysis for Reduced-Divergence Departures — Resubmission, Montréal, Canada, 5 to 16 May 2014