Big data analysis of irregular operations: Aborted approaches and their underlying factors

Procedures such as Missed Approaches and Holding Patterns are designed into Air Traffic Control procedures to provide a safe manner for flights to temporarily exit the airspace or the traffic flow when irregular operations occur. These procedures serve as “pressure release valves” and in this way are symptoms of the occurrence of infrequent phenomena that impact efficiency and safety margins. The occurrence of these procedures is not currently tracked by airlines or Air Navigation Service Providers (ANSP) due to the inability to identify these situations using the existing time-stamped event data (i.e. OOOI data) that is the basis for NAS performance analysis today. This paper describes a Big Data analysis of surveillance track data to establish the frequency of occurrence of Aborted Approaches, and an analysis of voluntary pilot/air traffic controller reports to establish factors leading to Aborted Approaches. Aborted Approaches include a Go Around for a Missed Approach as well as a turn off the final approach segment prior to the Missed Approach Point (MAP). Analysis of 21 days of surveillance track data for approaches at ORD identified a 7.4 in 1000 frequency of approaches resulting in an Aborted Approach. Daily Aborted Approaches ranged from 0 per day to 21 per 1000 approaches per day. Eighty percent of the Aborted Approaches involved a turn off the final approach segment prior to the MAP. An analysis of 467 voluntary pilot/air traffic controller reports from all U.S. airports identified factors leading to aborted approaches: (1) 48% airplane issues (e.g. onboard failure, unstable approach), (2) 27% traffic separation issues, (3) 16% weather (e.g. ceiling, visibility, crosswind), (4) 5% runway issues, and (5) 4% flightcrew-ATC interaction issues. These results suggest mitigation strategies to reduce the high variance in daily occurrences through procedure modification, training and equipment design.