Systematic Air Traffic Management in a Regular Lattice

A regular lattice combines two ideas: a repeating (or regular) airspace structure and layers of parallel tracks. A repeating or regular airspace structure has several advantages over an irregular structure. The skills or methods used to control traffic in one part of the structure are applicable throughout the structure. Regularity gives rise to multiple routes between two points with similar distances flown in each direction and at each flight level. Flow management can select routes which distribute traffic over a region. The same mechanism could be used to choose routes which avoid reserved areas. Since the possible routes between two points have similar properties, the selection of an alternative route has a small impact on flight time, contributing to the predictability of airline operations. Properties which apply to an element of the airspace apply wherever that element is repeated, so that reasoning about a small region of the airspace can immediately be scaled up to apply to a much larger region. Layers of parallel tracks eliminate crossing conflicts between aircraft which are flying straight and level. Together with measures to preserve the stability of traffic flows (sufficient spacing, speed regulation, or ASAS sequencing procedures), traffic may be separated into two easily identifiable populations: a "stable" population of cruising aircraft, which require low controller monitoring per aircraft, since there are no crossing conflicts between cruising aircraft, and a population of aircraft in "transition" to or from the stable state, which require greater monitoring. Some preliminary results from fast-time simulations are reported. Introduction: goals, problems and opportunities SESAR Goals The European Commission’s (EC) expectation for Single European Sky ATM Research (SESAR) is that it will deliver a European Air Traffic Management (ATM) System for 2020 and beyond which can meet the following goals relative to today’s performance [SESAR1]: • Safety Increase 10 times • Capacity Increase 3 times • ATM costs Divide by 2 • Environmental impact Reduce by 10% Safety On July 1 2002 a Tupolev TU154M passenger aircraft and a Boeing 757-200 cargo aircraft collided near the German town of Uberlingen killing all passengers and crew. [AX001-1-2/02]. Figure 1 [taken from AX001-1-2/02 A1&3] shows the paths of the aircraft, and their positions about 3 minutes before the accident. Both aircraft were at the same flight level. Figure 1: Radar tracks of flights in the Uberlingen mid-air collision If, at this time, an instruction had been given to either aircraft to modify its trajectory the situation would have been quite nominal. The accident illustrates a feature of the air traffic control system: aircraft with converging headings may cruise at the same flight level. There are many barriers to the occurrence of conflict and collision, and even should all the barriers fail collision is unlikely. One of the most important barriers is the vigilance of the air traffic controller. However, human vigilance cannot be infallible and the airborne collision avoidance system (ACAS/TCAS) cannot guarantee the prevention of collision. It would be desirable, wherever feasible, to reduce the