Progress Has Been Made in Reducing Runway Incursions, but Recent Incidents Underscore the Need for Further Proactive Efforts, May 24, 2007, Audit, Project ID: AV-2007-050 (44 pages, PDF): "On May 24, 2007, we issued our final report on the Federal Aviation Administration's (FAA) actions to address runway incursions at Boston Logan, Chicago O'Hare, Philadelphia, and Los Angeles International Airports. Overall, we found that FAA, airlines, and airport operators had taken actions to address runway incursions. However, those actions were taken only after an increase in the number and severity of incidents that occurred at those airports. Preventing runway incursions throughout the National Airspace System requires continuous vigilance on the part of FAA and users. Compared to 5 years ago, FAA has made significant progress in reducing those incidents. However, the serious risks associated with runway incursions underscore the need for maintaining a proactive approach for preventing serious incidents. We made six recommendations focusing on programmatic actions that could help FAA to reduce runway incursions system-wide."