Failures of critical systems at airports: Impact on aircraft operations and safety

Abstract

Failures of critical systems at airports can significantly impact aircraft operations and cause substantial safety risks. This study develops a generalized method for measuring the impacts of unscheduled communication, navigation and surveillance systems outages on airport operational performance (i.e. throughput) and safety. The proposed method consists of two separate models – the aggregate and the disaggregate model. The aggregate model is a regression model that analyzes flight data, which are averaged per quarter hour and obtained from the Aviation System Performance Metrics database, and investigates the reductions in airport throughput due to an outage. The disaggregate model analyzes individual flights using the Performance Data Analysis and Reporting System database to investigate air traffic controllers’ terminal airspace traffic management procedures during an outage by examining the time-separation (i.e. headways) between consecutive arriving aircraft on each runway. More specifically, the model calculates the changes in the probability of a loss of separation and assesses the necessity of enacting a Traffic Management Initiative. The proposed method is tested on the case of two localizer outages at Los Angeles International Airport. The case-study results reveal that the throughput decreased after air traffic controllers enacted a Ground Delay Program during the first observed outage. The probability of a loss of separation doubled and the smaller aircraft were diverted to other airports. Further results indicate that arriving headways can be better described by a combination of two probability distributions, rather than a single distribution, in order to more accurately capture a complexity of air traffic controllers’ actions. The method can help aviation regulators: (1) make better decisions about the value of equipment and redundancies, (2) analyze operational and safety degradations caused by equipment failures, and (3) develop appropriate traffic management procedures and improve existing ones.