3 research outputs found
Queuing Model for Taxi-Out Time Estimation
Flights incur a large percentage of their delays on the ground during the departure process
between their scheduled departure from the gate and takeoff. Because of the large uncertainties
associated with them, these delays are difficult to predict and account for, hindering the ability to
effectively manage the Air Traffic Control (ATC) system. This paper presents an effort to
improve the accuracy of estimating the taxi-out time, which is the duration between pushback
and takeoff. The method was to identify the main factors that affect the taxi-out time and build
an estimation model that takes the most important ones into account. An analysis conducted at
Boston Logan International Airport identified the runway configuration, the airline/terminal, the
downstream restrictions and the takeoff queue size as the main causal factors that affect the taxiout
time. Of these factors the takeoff queue size was the most important one, where the queue
size that an aircraft experienced was measured as the number of takeoffs that took place between
its pushback time and its takeoff time. Consequently, a queuing model was built to estimate the
taxi-out time at Logan Airport based on queue size estimation. For each aircraft, the queuing
model assumes knowledge of the number of departure aircraft present on the airport surface at its
pushback time and estimates its takeoff queue size by predicting the amount of passing that it
may experience on the airport surface during its taxi out. The prediction performance of the
queuing model was compared at Logan Airport to a running average model, which represents the
baseline used currently in the Enhanced Traffic Management System (ETMS). The running
average model uses a fourteen-day average as the estimate of the taxi-out time. The queuing
model improved the mean absolute error in the taxi-out time estimation by approximately twenty
percent and the accuracy rate by approximately ten percent, over the fourteen-day running average model.The work described in the paper was supported by NASA Ames Research Center
(NASA Grant NCC 2-1149) and the FAA National Center of Excellence for Aviation Operations
Research (NEXTOR)