Statistical characterization of deviations from planned flight trajectories in air traffic management

TL;DR

This study analyzes the statistical properties of planned versus realized flight trajectories in German airspace, revealing patterns in deviations and introducing a new metric to identify key navigation points affecting traffic management.

Contribution

It provides a detailed statistical analysis of flight deviations and introduces the difork metric to identify navigation points influencing deviations, enhancing understanding of traffic flexibility and stability.

Findings

Realized trajectories are shorter than planned, especially at night.

Deviations are more common near departure points and at large angles to destination.

Deviations are more frequent during low traffic phases.

Abstract

Understanding the relation between planned and realized flight trajectories and the determinants of flight deviations is of great importance in air traffic management. In this paper we perform an in depth investigation of the statistical properties of planned and realized air traffic on the German airspace during a 28 day periods, corresponding to an AIRAC cycle. We find that realized trajectories are on average shorter than planned ones and this effect is stronger during night-time than daytime. Flights are more frequently deviated close to the departure airport and at a relatively large angle to destination. Moreover, the probability of a deviation is higher in low traffic phases. All these evidences indicate that deviations are mostly used by controllers to give directs to flights when traffic conditions allow it. Finally we introduce a new metric, termed difork, which is able to characterize navigation points according to the likelihood that a deviation occurs there. Difork allows to identify in a statistically rigorous way navigation point pairs where deviations are more (less) frequent than expected under a null hypothesis of randomness that takes into account the heterogeneity of the navigation points. Such pairs can therefore be seen as sources of flexibility (stability) of controllers traffic management while conjugating safety and efficiency.