Increasing runway throughput is an important goal to achieve for any European airport and for Schiphol airport this is not different. Initially, one might think that such a goal would serve merely an economic goal, i.e. accommodating more traffic or reducing delay. However, increased runway throughput can also reduce noise annoyance in the vicinity of an airport by shortening the time period during which a runway is actively used.
In Europe collective developments have been undertaken through SESAR and by EUROCONTROL to increase runway throughput. These activities address an array of potential solutions, with separation reduction on final approach, under nominal weather conditions, as the primary objective. To achieve this objective, EUROCONTROL has developed a concept to reduce the amount of extra separation that must be applied between aircraft pairs, to meet wake-turbulence separation standards. For this, EUROCONTROL developed a re-categorization of the Wake Turbulence Categories (WTC) as defined by ICAO. The initiative splits the Heavy category in upper- and lower Heavy categories and the Medium category in upper- and lower Medium categories. The addition of new categories results in lower separation minima for many aircraft pairs.
The EUROCONTROL concept to recategorize WTC is called RECAT-EU and can be applied to both arriving and departing traffic streams. It is expected that Schiphol airport will benefit from the wake-turbulence recategorization. The objective of the KDC RECAT-EU study was to provide insight into the expected capacity increase with the introduction of RECAT-EU for departures. Furthermore, the study aimed at providing insight into:
- the factors that influence or are relevant to the expected capacity increase;
- resources that could be deployed to promote the realization of expected capacity gains;
- safety aspects of the RECAT-EU operation for departures.
In this study, FerWay and MovingDot analyzed the factors that have a bearing on the departure capacity at Schiphol, in particular in relation to the potential introduction of RECAT-EU versus currently applied ICAO WTC separation criteria. The analysis revealed many factors that influence the start interval and the magnitude of this impact. The results provide an insight into real life operations at Schiphol where currently visual, time- and distance-based separation is provided, but now looking at it from only a time-perspective that is considered to be implemented with RECAT-EU.
The most influential factor is the WTC or RECAT-EU category itself. Most aircraft-pairs showed separations corresponding to the specified by ICAO. Remarkably, the Heavy-Medium pair show an average spacing of 140 seconds, which is 20 seconds more than the minimum required spacing of 120 seconds. This is inherent to the takeoff clearance process where the controllers, for the Heavy-Medium pair only, apply 120 seconds between the takeoff roll and the next clearance. Other elements of influence include SID construction (divergence), runway dependencies and speed differences having the strongest impact. SID construction has a significant impact on departure timing and therefore on capacity.
More information and all results can be found in the report, which can be downloaded below.