Estimating Departure Queues to Study Runway Efficiency

Stephen C. Atkins


ABSTRACT

The ability to analyze the current efficiency of surface operations is limited by the lack of 
availability of surface surveillance data. To study surface and departure issues, and identify 
opportunities for automation to improve traffic management, this paper first presents a 
method for reconstructing the departure queues that existed at each runway from available 
information. Observations of the departure queues are of particular interest because they 
provide insight into the management of departures prior to takeoff. The method correlates 
pushback data and radar data to estimate the departure runway, the takeoff time, and the time 
at which the aircraft joins the departure queue, for every departure. By calculating the 
interval of time for which each aircraft is waiting at the runway, the departure queue at each 
runway can be reconstructed at every point in time. The paper uses this method to study five 
days of data from Dallas/Fort Worth airport. Substantial departure queues and delays are 
observed, consistent with expectations for a hub airport. Moreover, knowledge of the 
departure queues provides insight into the efficiency with which the departure runways were 
used. The departure queues on the primary departure runways are shown to be well balanced 
at most times. However, during periods of time when departure demand was present at the 
runway, the inter-departure gaps exhibit significant variability. These delays between 
consecutive departures may indicate an opportunity for automation to increase throughput.