Application of Unified Departure Operation Spacing to a Large Hub Airport

Kurzfassung

On large airports with numerous departures per hour, controllers need to organize departing aircraft in such a way that maximum throughput is achieved. The demanded initial spacing of departures from the same runway, or dependent runways, poses a limiting factor. On most airports, an aircraft that follows the same departure pattern as its predecessor, a so called “in-trail departure”, requires radar separation of 3 nautical miles (NM). If the departure direction diverges more than 15 degrees, controllers may apply reduced initial spacing of 2,400 meters (approx. 1.3 NM) according to the International Civil Aviation Organization (ICAO), or 6000 feet (ft) according to the Federal Aviation Administration (FAA), which allows earlier take-off clearance for following traffic, and thus higher throughput of the airport. The Unified Departure Operation Spacing (UDOS) concept allows the controller to apply reduced initial spacing, even for in-trail departures, if certain conditions are met. Those conditions include non-increasing distance to the preceding aircraft until radar separation is established, a Standard Instrument Departure (SID) with a target speed, established separation after at most 10 NM along track, and the presence of jet engines on the according aircraft. This paper investigates the departure situation on a large German airport hub and determines the potential of the UDOS concept on this particular airport. The current separation standards, including definitions of both ICAO and FAA, as well as the UDOS concept are reviewed. Prerequisites for the application of UDOS on that airport hub are presented and evaluated. Real data of departure operations on the airport in focus is available for multiple days of operation, including detailed information on the aircraft type, the actual take-off time (ATOT), and the assigned SID. By using this information, a baseline scenario for each available day of operations is constructed and investigated on presumably applied separation. Subsequently, an optimized departure scenario is established, allowing reduced initial spacing, and thus faster take-off clearance, whenever a flight qualifies for reduced separation. The qualification is determined by the evaluation of anticipated trajectories, based on the given SID route, the aircraft type, and a fuel weight estimation considering the designated arrival airport. A theoretical gain in departures per hour, when using the UDOS concept, is determined. Simulation of these scenarios is performed by operating the simulation environment of DLR's Institute of Flight Guidance. Departure trajectories are created with the air traffic simulator TrafficSim, which has been designed to support development of air traffic scenarios. It uses EUROCONTROL's Base of Aircraft Data (BADA) in order to generate precise trajectories for many different aircraft types, and is capable of simulating up to 30,000 aircraft in real time. All aircraft in the investigated scenarios are equipped with a flight management system (FMS) that can satisfy altitude constraints as well as time constraints and speed constraints. Conflict-freeness of the optimized scenario is ensured by using highly precise and fast conflict detection algorithms available in DLR's FATS.