Aircraft departure sequencing at major airports such a Heathrow is an important example of planning under uncertainty. The departure sequence must satisfy a set of hard constraints, concerned with the sizes and routes of successive departing aircraft, and should also be optimized with respect to a further set of soft constraints. From departure stand to take-off, each aircraft comes under the responsibility of first a Ground Movement Planner, then a Ground Movement Controller and finally a Take-Off Controller. There is most scope for resequencing while aircraft are at the stands, but also most uncertainty in how the decisions taken will affect the final sequence at take-off. In contrast, the Take-Off Controller experiences little uncertainty, but also has limited resequencing options, determined by the geometry of runway holding points. There is currently no complete mathematical formulation.

This project was designed to suggest ways of clarifying the potential gains from resequencing and the most suitable algorithms to apply at each stage, bearing in mind the differing levels of uncertainty. It consisted of three separate contributions, from Cardiff University, City University and the European Study Group with Industry.

Industrial project manager
John Greenwood, National Air Traffic Services

Cardiff University contributors
Stuart Allen, Steve Hurley, Roger Whitaker

City University contributor
Celia Glass

Study Group contributors
Alan Craig (University of Durham
Robert Ketzscher (Cranfield University)
Robert Leese (Smith Institute)
Steven Noble (Brunel University)
Kevin Parrott (University of Greenwich)
John Preater (Keele University)
Eddie Wilson (University of Bristol)
David Wood (University of Warwick)

Parallel processing at the Keele Study Group. From left to right, Alan Craig, Robert Leese, John Preater, Steve Noble, Kevin Parrott and Robert Ketzscher.