Point Merge

Point Merge

Description

Point merge is a method for sequencing arrival traffic flows. It was designed to accomodate high traffic loads without radar vectoring thus reducing controller workload while providing efficiency in terms of continuous descent and optimal sequencing.

Point merge is based on P-RNAV route structure, consisting of a point (the merge point) and pre-defined legs (the sequencing legs) in the form of arcs which makes them equidistant from this point. Sequencing is achieving by "direct to" instructions at appropriate moments. The legs are used to delay the aircraft by stretching their flight paths. Regardless of when the direct instruction is issued, the distance flown from that moment until reaching the merge point is the same.

Sequencing of arrival traffic can be done using several methods. Initially, radar vectoring was used for this purpose. This allowed for great flexibility but at the cost of increased workload (both in terms of situation monitoring and frequency occupancy). Later, PBN procedures were introduced in some TMAs as an alternative. These included path-stretching elements such as "trombone-shaped" routes which include a series of waypoints. While a "direct to" instructions between such waypoints offer solutions similar to point merge, these interventions are not standartized and besides, experience has shown that when traffic rises, controllers tend to revert to vectoring for final approach.

Benefits of using point merge include:

  • reduced controller workload. The aircraft are flying using own navigation and the only controller intervention is the "direct to" instruction. By contrast, if vectoring is used, the controller needs to issue several instructions, follow their execution and determine the appropriate timing of the next intervention. Furthermore, if the controller forgets about an aircraft due to distraction or is too busy to issue the next turning instruction, the aircraft will continue to fly on the last vector given, which may distort the whole sequencing plan and lead to multiple corrective instructions.
  • better pilot situational awareness. Pilots have a much better idea about their future flight path as opposed to the vectoring scenario.
  • more orderly traffic flows. Once established, the flight sequencing is easy to maintain as the aircraft effectively follow the same path.
  • better trajectory prediction resulting in increased flight efficiency. After the "direct to" instruction, the distance to touchdown is known with very high certainty, and therefore, continuous descent may be executed.
  • standartization of operations. The aircraft follows the arc, then a straight line to the merge point and then a standard intercept of the final approach track.

Point merge was developed by the EUROCONTROL Experimental Centre (EEC) in 2006. After the first implementations in Oslo (2011) and Dublin (2012), the point merge method spread not only within the ECAC area, but also far beyond its borders. As of August 2024, the procedure has been deployed in terminal areas around 50 airports across four continents, e.g. Istanbul, Tokyo, Shanghai, Mexico, Moscow, Kuala Lumpur, etc.

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