Evaluating near midair collision reporting systems using aircraft surveillance data: A case study at a university airport

Introduction: A near midair collision (NMAC) is defined by the Federal Aviation Administration as an event in which the crew of an aircraft perceives a situation that could lead to a midair collision or an event in which the separation between two aircraft is less than 500 feet (Federal Aviation Administration, 2018). NMAC reports collected by safety reporting systems have long been used to study and mitigate midair collision risk. However, reports submitted are subjective and require the reporter to voluntarily provide this information. With the implementation of Automatic Dependent Surveillance-Broadcast, aircraft temporal and positional data are easily collectible. Method: Using internal safety system, NASA Aviation Safety Reporting System, and FAA Near Midair Collision System reports together with ADS-B data, the effectiveness of different safety reporting systems to collect NMAC data around a towered university airport were compared over a six-month period. Unreported events were identified by utilizing ADS-B data to calculate aircraft separation events of less than 500 feet. Results: While 10 events were reported to the internal safety system, only one was reported to the NASA ASRS, and none to the FAA NMACS within the study’s scope. Sixteen events in which aircraft were within 500 feet of each other were found using ADS-B data, with none of these events having been reported to any safety reporting system. Conclusions: The findings of this study highlight the need for increased sharing in aviation safety data and show the potential of ADS-B data as a tool in studying near midair collisions and midair collision risk. Practical Applications: NMAC safety reporting systems may be less effective than expected. The addition of other sources of data such as ADS-B may be necessary to identify and investigate NMACs and other relevant near miss safety events.