The increased pressure to reduce aircraft emissions and the growing demand for air travel causes airports to consider alternatives for fuel-inefficient aircraft taxiing. External towing tugs can be deployed to effectively reduce on-ground fuel burn of outbound aircraft. These new operations are likely to aggravate ground delays as a result of flow-disturbing uncoupling processes on taxiways or holding platforms. The size of these delays has not been previously investigated. The goal of this research is to analyse the impact of various uncoupling scenarios on ground delays. Scenarios are created by varying the uncoupling duration and the available uncoupling points. A computational model is created with Amsterdam Airport Schiphol (AAS) and Taxibot as reference airport and towing system. Vehicle-specific operations are optimised by a hierarchical multi-agent path planning algorithm. The algorithm comprises augmented versions of a Priority Based Search (PBS) algorithm and a Safe Interval Path Planning (SIPP) technique. Simulated conventional operations are compared with Taxibot-enabled operations for traffic samples corresponding to high traffic demands. Minor delays are found for inbound traffic. For outbound traffic, most delays occur during towing and are mainly determined by the arrangement of uncoupling points, the uncoupling duration, and the traffic demand. Delays are furthermore, but to a lesser extent, determined by the changed kinematics of aircraft towing and the runway’s position. Delays resulting from uncoupling only on taxiways or holding platforms vary per runway as a result of different arrangements in uncoupling points. For every arrangement of uncoupling points, the number of points and the presence of alternative paths around the points are key in mitigating delays resulting from long uncoupling processes. The intensity of delays can be reduced by tuning search objective settings in the algorithm, in particular for uncoupling points arranged in series.

Last January, yet another attempt to reach consensus on the growth of Schiphol has failed. Schiphol, KLM and other large airliners request a growth of 10,000 extra flight movements per year, while habitants, governors of municipalities and province and environmental organisations request a growth stop until 2023. The main arguments are noise disturbance in the surroundings of Schiphol and the negative effects of aviation on the local and global environment 1. In order to stop the limitations on aviation growth, structural changes will have to be made in the industry. One of the proposed solutions is to remove the conventional landing gear and make use of a ground based powered system to perform the landing and take-off. Firstly, the intended result is a reduction in fuel emissions due to the weight reduction of the aircraft: a conventional landing gear counts for approximately 4% of the maximum take-off weight of the aircraft. Secondly, the use of a ground based powered system provides for the opportunity to reduce noise pollution during take-off and landing. These two advantages are exactly tackling the two major issues that prevents airports like Schiphol, from growing...