Runway Safety: Progress on Reducing Runway Incursions Impeded by Leadership, Technology, and Other Challenges
Released: 2008-02-13T00:00:00

Letter

Number and Rate of Incursions Show Upward Trend

Runway safety is a longstanding major aviation safety concern; prevention of runway incursions, which are precursors to aviation accidents, has been on NTSB’s list of most wanted transportation improvements since 1990 because runway collisions can be catastrophic. Recent data indicate that runway incursions are growing and may become even more numerous as the volume of air traffic increases. The number and rate of incursions declined from a peak in fiscal year 2001 and remained relatively constant for the next 5 years. However, from fiscal years 2006 through 2007, the number and rate of incursions increased by 12 percent and nearly regained the 2001 peak (see fig. 1).

Additionally, data for the first quarter of fiscal year 2008 show that the number of incursions increased substantially after FAA began using a definition of incursions developed by the International Civil Aviation Organization (ICAO), a United Nations specialized agency. Using the ICAO definition, FAA is now counting some incidents as incursions that had been formerly classified as surface incidents. During the first quarter of fiscal year 2008, using the ICAO definition, FAA counted 230 incursions. If FAA had continued to use its previous definition, it would have counted 94 incursions. According to an FAA official, by adopting the ICAO definition, FAA expects to report about 900 to 1,000 incursions this year. Fig. 2 shows the number and rate of incursions, by quarter, during fiscal year 2007 and during the first quarter of fiscal year 2008.

Moreover, the number and rate of serious incursions—where collisions were narrowly or barely avoided—increased substantially during the first quarter of fiscal year 2008, compared to the same quarter in fiscal year 2007. During the first quarter of fiscal year 2008, 10 serious incursions occurred, compared to 2 serious incursions during the first quarter of fiscal year 2007. (See fig. 3.)

Most runway incursions involve general aviation aircraft. According to FAA, 72 percent of incursions from fiscal years 2003 through 2006 involved at least one general aviation aircraft. However, about one-third of the most serious incursions from fiscal years 2002 through 2007—about 9 per year—involved at least one commercial aircraft that can carry many passengers. That number includes two serious incursions that occurred just two months ago, in December 2007. (See table 3 in the appendix for additional information on recent serious incursions.) Figure 4 shows the number of serious incursions involving commercial aircraft from fiscal years 2001 through 2007.

In the United States, most incursions have occurred at major commercial airports, where the volume of traffic is greater. Los Angeles International Airport and Chicago O’Hare International Airport had the greatest number of runway incursions from fiscal years 2001 through 2007, as shown in fig. 5.

The primary causes of incursions, as cited by experts we surveyed and some airport officials, include human factors issues, such as miscommunication between air traffic controllers and pilots, a lack of situational awareness on the airfield by pilots, and performance and judgment errors by air traffic controllers and pilots. According to FAA, 57 percent of incursions during fiscal year 2007 were caused by pilot errors, 28 percent were caused by air traffic controller errors, and 15 percent were caused by vehicle operator or pedestrian errors (see fig. 6).

Challenges Remain Despite Numerous Efforts to Address Runway Safety

FAA, airports, and airlines have taken steps to address runway safety, but the lack of leadership and coordination, technology challenges, lack of data, and human factors-related issues impede further progress. To improve runway safety, FAA has deployed and tested technology designed to prevent runway collisions; promoted changes in airport layout, markings, signage, and lighting; and provided training for pilots and air traffic controllers. In addition, in August 2007, following several serious incursions, FAA met with aviation community stakeholders and agreed on a short-term plan to improve runway safety. In January 2008, FAA reported on the status of those actions, which included accelerating the upgrading of airport markings, which were originally required to be completed by June 30, 2008, at medium and large airports, upgrading markings at smaller commercial airports, which had not completing a runway safety review of 20 airports that were selected on the basis of runway incident data, and requiring that nonairport employees, such as airline mechanics, receive recurrent driver training at 385 airports.

According to FAA, since the August 2007 meeting, all 112 active air carriers have reported that they are (1) providing pilots with similar or other training that incorporates scenarios from aircraft pushback through taxi, and (2) reviewing procedures to identify and develop a plan to address elements that contribute to pilot distraction while taxiing. FAA also indicated that it had completed an analysis of air traffic control procedures pertaining to taxi clearances and found that more explicit taxi instructions are needed, and that it had signed a partnership agreement with the National Air Traffic Controllers Association to create a voluntary safety reporting system for air traffic controllers.

In our November 2007 report, we found that FAA’s Office of Runway Safety had not carried out its leadership role to coordinate and monitor the agency’s runway safety efforts. Until recently, the office did not have a permanent director for the previous 2 years and staffing levels declined. FAA took a positive step by hiring a permanent director at the Senior Executive Service level for the office in August 2007. The new director has indicated he is considering several initiatives, including establishing a joint FAA-industry working group to analyze the causes of incursions and track runway safety improvements. In our November 2007 report, we also found that FAA had not updated its national runway safety plan since 2002, despite agency policy that such a plan be prepared every 2 to 3 years. The lack of an updated plan resulted in uncoordinated runway safety efforts by individual FAA offices. For example, in the absence of an updated national runway plan, each FAA office is expected to separately include its runway safety initiatives in its own business plan. However, this practice does not provide the same national focus and emphasis on runway safety that a national plan provides. Furthermore, not all offices with runway safety responsibilities included efforts to reduce incursions in their business plans. Until the national runway safety plan is updated, the agency lacks a comprehensive, coordinated strategy to provide a sustained level of attention to improving runway safety.

The deployment of surface surveillance technology to airports is a major part of FAA’s strategy to improve runway safety, but it has presented challenges. To provide ground surveillance, FAA has deployed the Airport Movement Area Safety System (AMASS), which uses the Airport Surface Detection Equipment-3 (ASDE-3) radar, at 34 of the nation’s busiest airports and is deploying an updated system, ASDE-X, at 35 major airports. The current deployment schedule will result in a total of 44 airports having AMASS and/or ASDE-X (see table 5 in the appendix). Both systems are designed to provide controllers with alerts when they detect a possible collision on the ground. As of January 2008, ASDE-X was commissioned at 11 of the 35 airports scheduled to receive it. FAA is also testing runway status lights, which are a series of lights embedded in the runways that give pilots a visible warning when runways are not clear to enter, cross, or depart on, at the Dallas-Ft. Worth International Airport and the San Diego International Airport. The agency made an initial investment decision last year to deploy the system at 19 airports, starting in November 2009, and is planning to make a final investment decision in June 2008. In addition, FAA is testing the Final Approach Runway Occupancy Signal at the Long Beach-Daugherty Field airport in California, which activates a flashing light visible to aircraft on approach as a warning to pilots when a runway is occupied and hazardous for landing.

However, FAA risks not meeting its current ASDE-X cost and schedule plans, which have been revised twice since 2001, and the system is experiencing operational difficulties with its alerting function. Although it took about 4 years for ASDE-X to be commissioned at 11 airports, FAA plans to deploy the system at the remaining 24 additional airports by 2010. In addition, not all 11 ASDE-X airports have key safety features of the system. For example, as of January 2008, two ASDE-X airports did not have safety logic, which generates a visible and audible alert to an air traffic controller regarding a potential runway collision. Furthermore, the ASDE-X airports are experiencing problems with false alerts, which occur when the system incorrectly predicts an impending collision, and false targets, which occur when the system incorrectly identifies something on the airfield as an aircraft or vehicle and could generate a false alert. Moreover, most airports in the United States have no runway safety technology to supplement a controller’s vision of the airfield and will not have such technology even after FAA completes its plan to deploy ASDE-X at 35 major airports. While FAA is testing additional technology to prevent runway collisions, such as the Final Approach Runway Occupancy Signal, the systems are years away from deployment. Another technology, runway status lights, have had positive preliminary test evaluations, but need a surface surveillance system such as ASDE-3/AMASS or ASDE-X to operate. In addition, FAA is still testing a low cost surface surveillance system that already is being used at 44 airports outside of the United States. Furthermore, systems that provide direct collision warnings to flight crews, which NTSB and experts have recommended, are still being developed.

FAA lacks reliable runway safety data and the mechanisms to ensure that the data are complete. Although FAA collects information about runway incursions and classifies their severity, its tabulation of the number of incursions does not reflect the actual number of incidents that occur. FAA only counts incursions that occur at airports with air traffic control towers, so the actual number of incursions, which includes those that occurred at airports without air traffic control towers, is higher than FAA reports. While the change in definition of incursions that FAA adopted at the beginning of fiscal year 2008 will increase the number of incursions counted, it will not address this problem. In addition, an internal agency audit of 2006 incursion data questioned the accuracy of some of the incursion severity classifications. FAA plans to start a nonpunitive, confidential, voluntary program for air traffic controllers similar to a program that FAA has already established for pilots and others in the aviation community. The new program will enable air traffic controllers to report anything that they perceive could contribute to safety risks in the national airspace system. The benefit of such program is that the information obtained might not be reported otherwise, and could increase the amount of data collected on the causes and circumstances of runway incursions. However, FAA has not indicated when such a program would be implemented.

FAA has also taken some steps to address human factors issues through educational initiatives, such as developing simulated recreations of actual incursions to enhance air traffic controller training. However, air traffic controller fatigue, which may result from regularly working overtime, continues to be a human factors issue affecting runway safety. NTSB, which investigates transportation accidents, has identified four instances from 2001 through 2006 when tired controllers made errors that resulted in serious incursions. We found that, as of May 2007, at least 20 percent of the controllers at 25 air traffic control facilities, including towers at several of the country’s busiest airports, were regularly working 6-day weeks. (See table 7 in the appendix for additional information.)

Experts we surveyed indicated that the actions that FAA could take with the greatest potential to prevent runway incursions, considering costs, technological feasibility, and operational changes, were measures to provide information or alerts directly to pilots. Experts believed that lighting systems that guide pilots as they taxi at the airport, and technology that provides enhanced situational awareness on the airfield and alerts of potential incursions, would be of particular importance.

Recommendations

In our November 2007 report, we recommended that FAA (1) prepare a new national runway safety plan, (2) develop an implementation schedule for establishing a nonpunitive voluntary safety reporting program for air traffic controllers, and (3) develop a mitigation plan for addressing controller overtime. The agency agreed to consider our recommendations.

In closing, although FAA has taken many actions to improve runway safety, the number of serious incursions that are continuing to occur— many of which involved aircraft carrying hundreds of passengers— suggests that this country continues to face a high risk of a catastrophic runway collision. FAA must provide sustained attention to improving runway safety through leadership, technology, and other means. As the volume of air traffic continues to increase, providing sustained attention to runway safety will become even more critical.

Mr. Chairman, this concludes my prepared statement. I would be pleased to respond to any questions from you or other members of the Subcommittee.

GAO Contact and Staff Acknowledgments

For further information on this testimony, please contact Dr. Gerald L. Dillingham at (202) 512-2834 or dillinghamg@gao.gov. Individuals making key contributions to this testimony include Teresa Spisak, Bob Homan, and David Goldstein.