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Report No: DOT/FAA/AM-93/22

Title and Subtitle: An Analysis of the Operational Error Database for Air Route Traffic Control Centers

Report Date: December 1993

Authors: Rodgers, M.D.

Abstract: Monitoring the frequency and determining the causes of operational errors - defined as the loss of prescribed separation between aircraft - is one approach to assessing the operational safety of the air traffic control system. The Federal Aviation Administration (FAA) refers to the loss of separation standards between aircraft as an operational error (OE). The extent to which separation is lost determines the severity of the error.

The first study examined the relationships between error occurrence, controller workload (number of aircraft and traffic complexity) and causal factors involved. The FAA's Final Operational Error/Deviation Reports for ARTCC facilities during calendar years 1985-88 comprised the data base. A majority of the errors occurred under conditions of below average (25%) or average (39%) complexity. Complexity and number of aircraft were highly correlated. However, there was a significant difference across facilities in average workload during an event. Improved guidelines for quality assurance personnel are needed to insure a more standardized determination and reporting of workload dimensions. Results suggested that the frequency of some of the causal factors varied in response to changes in number of aircraft worked and traffic complexity.

The second study analyzed the workload and causal factors related to the severity of OEs at ARTCCs during 1988-91. Neither the number of aircraft being worked nor air traffic complexity were significantly associated with severity. In general, the causal factors that resulted in greater severity likely involved reduced situation awareness by the controller. The relationship of aircraft profiles and flight levels with OE severity were examined. Facility level differences were reviewed regarding controller workload and awareness of the developing error.

More in depth information is needed to determine precisely the manner in which alterations in workload influence the nature of the error process. Both studies point to the need for increasing the level of objectivity in the operational error investigation process.

Key Words: Air Traffic Control, Operational, Errors, Human Performance, Human, Factors, Workload

No. of Pages: 30