Runway Safety: Progress on Reducing Runway Incursions Impeded by 
Leadership, Technology, and Other Challenges (13-FEB-08,	 
GAO-08-481T).							 
                                                                 
While aviation accidents in the United States are relatively	 
infrequent, recent incidents have heightened concerns about	 
safety on airport runways. As the nation's aviation system	 
becomes more crowded every day, increased congestion at airports 
may exacerbate ground safety concerns. This statement discusses  
(1) the trends in runway incursions, (2) what FAA has done to	 
improve runway safety, and (3) what more could be done. This	 
statement is based on GAO's November 2007 report issued to this  
committee on runway safety. GAO's work on that report included	 
surveying experts on the causes of runway incidents and accidents
and the effectiveness of measures to address them, reviewing	 
safety data, and interviewing agency and industry officials. This
statement also contains information from FAA on recent incursions
and actions taken since November 2007.				 
-------------------------Indexing Terms------------------------- 
REPORTNUM:   GAO-08-481T					        
    ACCNO:   A80733						        
  TITLE:     Runway Safety: Progress on Reducing Runway Incursions    
Impeded by Leadership, Technology, and Other Challenges 	 
     DATE:   02/13/2008 
  SUBJECT:   Accident prevention				 
	     Air transportation 				 
	     Aircraft accidents 				 
	     Airports						 
	     Aviation						 
	     Aviation security					 
	     Commercial aviation				 
	     Research and development				 
	     Risk assessment					 
	     Risk factors					 
	     Risk management					 
	     Safety standards					 
	     Strategic planning 				 
	     Transportation planning				 
	     Transportation safety				 

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GAO-08-481T

   

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Testimony: 

Before the Subcommittee on Aviation, Committee on Transportation and 
Infrastructure, House of Representatives: 

United States Government Accountability Office: 

GAO: 

For Release on Delivery Expected at 2:00 p.m. EST: 

Wednesday, February 13, 2008: 

Runway Safety: 

Progress on Reducing Runway Incursions Impeded by Leadership, 
Technology, and Other Challenges: 

Statement of Gerald L. Dillingham, Ph.D. 

Director, Physical Infrastructure Issues: 

Runway Safety: 

GAO-08-481T: 

GAO Highlights: 

Highlights of GAO-08-481T, a testimony before the Subcommittee on 
Aviation, Committee on Transportation and Infrastructure, House of 
Representatives. 

Why GAO Did This Study: 

While aviation accidents in the United States are relatively 
infrequent, recent incidents have heightened concerns about safety on 
airport runways. As the nationï¿½s aviation system becomes more crowded 
every day, increased congestion at airports may exacerbate ground 
safety concerns. This statement discusses (1) the trends in runway 
incursions, (2) what FAA has done to improve runway safety, and (3) 
what more could be done. This statement is based on GAOï¿½s November 2007 
report issued to this committee on runway safety. GAOï¿½s work on that 
report included surveying experts on the causes of runway incidents and 
accidents and the effectiveness of measures to address them, reviewing 
safety data, and interviewing agency and industry officials. This 
statement also contains information from FAA on recent incursions and 
actions taken since November 2007. 

What GAO Found: 

Recent data indicate that runway incursions, which are precursors to 
aviation accidents, are growing. Although the number and rate of 
incursions declined after reaching a peak in fiscal year 2001 and 
remained relatively constant for the next 5 years, they show a recent 
upward trend. From fiscal year 2006 through fiscal year 2007, the 
number and rate of incursions increased by 12 percent and both were 
nearly as high as their 2001 peak. Furthermore, the number of serious 
incursionsï¿½where collisions are narrowly or barely avoidedï¿½increased 
from 2 during the first quarter of fiscal year 2007 to 10 during the 
same quarter in fiscal year 2008. 

FAA has taken steps to address runway safety, but further progress has 
been impeded by the lack of leadership and coordination, technology 
challenges, lack of data, and human factors-related issues. FAAï¿½s 
actions have included deploying and testing technology designed to 
prevent runway collisions and promoting changes in airport layout, 
markings, signage, and lighting. However, until recently, FAAï¿½s Office 
of Runway Safety did not have a permanent director. Also, FAA has not 
updated its national runway safety plan since 2002, despite agency 
policy that such a plan be prepared every 2 to 3 years, resulting in 
uncoordinated efforts within the agency. Moreover, runway safety 
technology currently being installed, which is designed to provide air 
traffic controllers with the position and identification of aircraft on 
the ground and alerts of potential collisions, is behind schedule and 
experiencing cost increases and operational difficulties with its 
alerting function. FAA also lacks reliable runway safety data and the 
mechanisms to ensure that the data are complete. Furthermore, air 
traffic controller fatigue, which may result from regularly working 
overtime, continues to be a matter of concern for the National 
Transportation Safety Board (NTSB) and others. 

FAA could take additional measures to improve runway safety. These 
measures include implementing GAOï¿½s recommendations to prepare a new 
national runway safety plan, address controller overtime and fatigue, 
and start a nonpunitive, confidential, voluntary program for air 
traffic controllers to report safety risks in the national airspace 
system, which would be similar to a program that FAA has already 
established for pilots and others in the aviation community. Such a 
program could help the agency to understand the causes and 
circumstances regarding runway safety incidents. Additional 
improvements, suggested by experts and NTSB, include developing and 
deploying technology to provide alerts directly to pilots. 

Figure: 

This is a figure of an airline portraying "Incursion." 

[See PDF for image] 

Source: GAO. 

[End of figure] 

What GAO Recommends: 

In prior work, GAO recommended that FAA take several measures to 
enhance runway safety, such as updating its national runway safety 
plan, collecting more complete data on runway incidents, and addressing 
air traffic controller fatigue. The agency agreed to consider the 
recommendations. 

To view the full product, including the scope and methodology, click on 
[hyperlink, http:///www.GAO-08-481T]. For more information, contact 
Gerald L. Dillingham, Ph.D., at (202) 512-2834. 

[End of section] 

Mr. Chairman and Members of the Subcommittee: 

Thank you for the opportunity to testify today on runway safety. While 
aviation accidents in the United States are relatively infrequent, 
recent incidents have heightened concerns about safety on airport 
runways. On August 16, 2007, for example, at Los Angeles International 
Airport--one of the nation's busiest airports--two commercial aircraft 
carrying 296 people came within 37 feet of colliding, resulting in an 
incident that is called a runway incursion. As the nation's aviation 
system becomes more crowded every day, increased congestion at airports 
may exacerbate ground safety concerns. At airports, the Federal 
Aviation Administration (FAA) focuses its safety oversight on the 
movement areas--runways and taxiways[Footnote 1]--where the chances of 
catastrophic accidents are greater than other areas. 

My testimony today is focused on (1) the trends in runway incursions, 
(2) what steps FAA has taken to improve runway safety, and (3) what 
more could be done. This statement is based on our November 2007 report 
on runway safety[Footnote 2] and work that we conducted between January 
2008 and February 2008 to obtain updated information on recent 
incursions and actions taken by FAA since our report was issued. Our 
work on the November 2007 report included surveying experts on the 
causes of runway incidents and accidents, the effectiveness of measures 
that are being taken to address them, and what additional measures 
could be taken. We conducted this work in accordance with generally 
accepted government auditing standards. Those standards require that we 
plan and perform the audit to obtain sufficient, appropriate evidence 
to provide a reasonable basis for our findings and conclusions based on 
our audit objectives. 

Summary: 

* Recent data indicate that runway incursions, which are precursors to 
aviation accidents, are growing. Although the number and rate of 
incursions declined after reaching a peak in fiscal year 2001 and 
remained relatively constant for the next 5 years, they show a recent 
upward trend. From fiscal years 2006 through 2007, the number and rate 
of incursions increased by 12 percent and were nearly as high as when 
they reached their 2001 peak. Furthermore, the number 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. 

* FAA has 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. However, until recently, FAA's Office of Runway Safety did 
not have a permanent director. Also, FAA has not updated its national 
runway safety plan since 2002, despite agency policy that such a plan 
be prepared every 2 to 3 years, which resulted in uncoordinated runway 
safety efforts by individual FAA offices. Moreover, the runway safety 
technology that FAA is currently installing, which is designed to 
provide air traffic controllers with the position and identification of 
aircraft on the ground and alerts of potential collisions, is behind 
schedule and experiencing cost increases and having operational 
difficulties with its alerting function. Additional technology to 
prevent runway incursions is years away from deployment. FAA also lacks 
reliable runway safety data and the mechanisms to ensure that the data 
are complete. Furthermore, air traffic controller fatigue, a human 
factors issue that may result from regularly working overtime, 
continues to be a matter of concern for the National Transportation 
Safety Board (NTSB) and other aviation stakeholders. 

* FAA could take additional measures to improve runway safety. In our 
November 2007 report, we recommended that FAA prepare a new national 
runway safety plan; address controller overtime and fatigue; and start 
a nonpunitive, confidential, voluntary program for air traffic 
controllers to report safety risks in the national airspace system, 
similar to a program that FAA has already established for pilots and 
others in the aviation community. Such a program could help the agency 
to understand the causes and circumstances regarding runway safety 
incidents. The agency agreed to consider our recommendations. 
Additional improvements, suggested by experts we surveyed and NTSB, 
include developing and deploying technology that provided alerts of 
potential incursions directly to pilots. 

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). 

Figure 1: Number and Rate of Runway Incursions from Fiscal Year 1998 
through Fiscal Year 2007: 

This figure is a combination line and bar graph showing the number and 
rate of runway incursions from fiscal year 1998 through fiscal year 
2007. The X axis is the fiscal year, the left Y axis is the number of 
runway incursions, and the right Y axis is the rate of runway 
incursions. The bars represent the number of runway incursions, and the 
line represents the rate of runway incursions (per 1 million tower 
operations.) 

[See PDF for image] 

Source: FAA. 

Note: Table 1 in the appendix shows data for fig. 1. 

[End of figure] 

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.[Footnote 3] Using the ICAO definition, FAA is now counting some 
incidents as incursions that had been formerly classified as surface 
incidents.[Footnote 4] 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. 

Figure 2: Incursions, by Quarter, during Fiscal Year 2007 and the First 
Quarter of Fiscal Year 2008: 

This figure is a combination line and bar chart showing incursions, by 
quarter, during fiscal year 2007 and the first quarter of fiscal year 
2008. The X axis represents the quarter, the left Y axis represents the 
number of incursions, and the right Y axis represents the rate of 
incursions. One of the lines represents incursion rate per 1 million 
tower operations (old definition), and the other line represents 
incursion rate per 1 million tower operations (new definition). One bar 
represents incursions (old definition), and the other represents 
incursions (new definition). 

[See PDF for image] 

Source: FAA. 

Note: Table 2 in the appendix provides the data for fig. 2. 

[End of figure] 

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.[Footnote 5] 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.) 

Figure 3: Serious Incursions, by Quarter, during Fiscal Year 2007 and 
the First Quarter of Fiscal Year 2008: 

This figure is a combination line and bar graph showing serious 
incursions, by quarter, during fiscal year 2007 and the first quarter 
of fiscal year 2008. The X axis is the quarter, the left Y axis is the 
number of incursions, and the right Y axis represents the rate of 
incursions. The line represents the incursion rate, and the bars 
represent incursions. 

[See PDF for image] 

Source: FAA. 

Note: FAA's adoption of the ICAO definition of incursions during the 
first quarter of fiscal year 2008 did not affect the number or rate of 
serious incursions. Table 2 in the appendix provides data for fig. 3. 

[End of figure] 

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. 

Figure 4: Total Number of Serious Incursions and Number of Serious 
Incursions Involving At Least One Commercial Aircraft, Fiscal Year 2001 
through Fiscal Year 2007: 

This figure is a shaded bar chart showing the total number of serious 
incursions involving at least one commercial aircraft, fiscal year 2001 
through fiscal year 2007. The X axis represents the fiscal year, and 
the Y axis represents the number of incursions. One bar represents 
serious incursions not involving commercial aircraft, and the other bar 
represents serious incursions involving at least one commercial 
aircraft. 

[See PDF for image] 

Source: FAA. 

Note: Table 4 in the appendix provides the data for fig. 4. 

[End of figure] 

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. 


Figure 5: U.S. Airports that Experienced the Most Runway Incursions 
from Fiscal Year 2001 through Fiscal Year 2007: 

This figure is a combination bar chart showing U.S. airports that 
experienced the most runway incursions from fiscal year 2001 through 
fiscal year 2007. The X axis represents the number of incursions, and 
the Y axis represents the airports. One bar represents serious 
incursions (categories A and B), and the other bar represents all other 
incursions (categories C and D). 

[See PDF for image] 

Source: GAO analysis of FAA data. 

Note: Information was compiled from a list of airports that experienced 
20 or more incursions from fiscal year 2001 through fiscal year 2007 
and were certificated under 14 CFR Part 139. This information expands 
upon the information we presented in GAO-08-29 (fig. 4), which only 
included the top 10 airports experiencing incursions from fiscal years 
2001 to 2006. In addition, we now include three airports--Long Beach- 
Daugherty Field, John Wayne-Orange County, and North Las Vegas--which 
were previously identified as general aviation airports. Table 5 in the 
appendix provides the data for fig. 5. 

[End of figure] 

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). 

Figure 6: Causes of Incursions during Fiscal Year 2007: 

This figure is a pie chart showing causes of incursions during fiscal 
year 2007. 

Pilot errors: 57%; 
Controller errors: 28%; 
Vehicle driver/pedestrian errors: 15%. 

[See PDF for image] 

Source: FAA. 

[End of figure] 

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 been 
required, 

* 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,[Footnote 6] 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[Footnote 7] 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.[Footnote 8] 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 [email protected]. Individuals making 
key contributions to this testimony include Teresa Spisak, Bob Homan, 
and David Goldstein. 

[End of section] 

Appendix I: Additional Runway Incident Data: 

Table 1: Number and Rate of Runway Incursions from Fiscal Year 1998 
through Fiscal Year 2007: 

Fiscal year: 1998; Number of incursions: 304; 
Rate per 1 million tower operations: 4.66. 

Fiscal year: 1999; 
Number of incursions: 329; 
Rate per 1 million tower operations: 4.83. 

Fiscal year: 2000; 
Number of incursions: 405; 
Rate per 1 million tower operations: 5.9. 

Fiscal year: 2001; 
Number of incursions: 407; 
Rate per 1 million tower operations: 6.1. 

Fiscal year: 2002; 
Number of incursions: 339; 
Rate per 1 million tower operations: 5.2. 

Fiscal year: 2003; 
Number of incursions: 323; 
Rate per 1 million tower operations: 5.1. 

Fiscal year: 2004; 
Number of incursions: 326; 
Rate per 1 million tower operations: 5.2. 

Fiscal year: 2005; 
Number of incursions: 327; 
Rate per 1 million tower operations: 5.2. 

Fiscal year: 2006; 
Number of incursions: 330; 
Rate per 1 million tower operations: 5.4. 

Fiscal year: 2007; 
Number of incursions: 370; 
Rate per 1 million tower operations: 6.05. 

Source: FAA. 

[End of table] 

Table 2: Number and Rate of Incursions, by Quarter, during Fiscal Year 
2007 and the First Quarter of Fiscal Year 2008: 

Quarter and fiscal year: First quarter 2007; 
Number of incursions: 90; 
Incursion rate per 1 million tower operations: 6.03; 
Number of serious incursions: 2; 
Rate of serious incursions per 1 million tower operations: 0.134. 

Quarter and fiscal year: Second quarter 2007; 
Number of incursions: 79; 
Incursion rate per 1 million tower operations: 5.533; 
Number of serious incursions: 5; 
Rate of serious incursions per 1 million tower operations: 0.3502. 

Quarter and fiscal year: Third quarter 2007; 
Number of incursions: 106; 
Incursion rate per 1 million tower operations: 6.709; 
Number of serious incursions: 10; 
Rate of serious incursions per 1 million tower operations: 0.6329. 

Quarter and fiscal year: Fourth quarter 2007; 
Number of incursions: 95; 
Incursion rate per 1 million tower operations: 5.891; 
Number of serious incursions: 7; 
Rate of serious incursions per 1 million tower operations: 0.4341. 

Quarter and fiscal year: First quarter 2008, using previous FAA 
incursion definition; 
Number of incursions: 94; 
Incursion rate per 1 million tower operations: 6.434; 
Number of serious incursions: 10; 
Rate of serious incursions per 1 million tower operations: 0.685. 

Quarter and fiscal year: First quarter 2008, using ICAO incursion 
definition; 
Number of incursions: 230; 
Incursion rate per 1 million tower operations: 15.744; 
Number of serious incursions: 10; 
Rate of serious incursions per 1 million tower operations: 0.685. 

Source: FAA. 

[End of table] 

Table 3: Serious Incursions Involving At Least One Commercial Aircraft 
from Fiscal Year 2006 through the First Quarter of Fiscal Year 2008. 

Date: October 13, 2005; 
Location: Gulfport-Biloxi International, MS; 
Airline(s) and aircraft involved: Northwest Airlines DC9 and Cessna 
C172; 
Number of air passengers: N/A. 

Date: March 21, 2006; 
Location: Chicago O'Hare International; 
Airline(s) and aircraft involved: Lufthansa Airbus A319 and Chautauqua 
Embraer E145; 
Number of air passengers: 78. 

Date: April 29, 2006; 
Location: Phoenix Sky Harbor International; 
Airline(s) and aircraft involved: US Airways Airbus A320 and 
pedestrian; 
Number of air passengers: N/A. 

Date: May 25, 2006; 
Location: Miami International; 
Airline(s) and aircraft involved: Boeing 747 and American Eagle 
Aerospatiale AT43; 
Number of air passengers: N/A. 

Date: July 18, 2006; 
Location: Chicago O'Hare International; 
Airline(s) and aircraft involved: American Eagle Canadair CRJ-700 and 
US Airways Boeing 737; 
Number of air passengers: N/A. 

Date: July 23, 2006; 
Location: Chicago O'Hare International; 
Airline(s) and aircraft involved: ATLAS Boeing 747 and United Airlines 
Boeing 737; 
Number of air passengers: 131. 

Date: July 26, 2006; 
Location: Los Angeles International; 
Airline(s) and aircraft involved: Mesa Canadair CRJ-200 and Skywest 
Embraer E120; 
Number of air passengers: N/A. 

Date: August 8, 2006; 
Location: Southwest Florida International, Ft. Myers, FL; 
Airline(s) and aircraft involved: Southwest Boeing 737 and vehicle; 
Number of air passengers: N/A. 

Date: September 30, 2006; 
Location: Los Angeles International; 
Airline(s) and aircraft involved: Gulfstream GLF5 and Skywest Canadair 
CRJ-700; 
Number of air passengers: N/A. 

Date: January 5, 2007; 
Location: Denver International; 
Airline(s) and aircraft involved: Key Lime Air Swearingen SW4 and 
Frontier Airbus A319; 
Number of air passengers: 50. 

Date: February 2, 2007; 
Location: Denver International; 
Airline(s) and aircraft involved: United Boeing 737 and snowplow; 
Number of air passengers: 101. 

Date: May 4, 2007; 
Location: Cyril E. King Airport, Charlotte Amalie, VI; 
Airline(s) and aircraft involved: American Airlines Boeing 757 and 
Cessna C208; 
Number of air passengers: N/A. 

Date: May 6, 2007; 
Location: Los Angeles International; 
Airline(s) and aircraft involved: Skywest Embraer 120 and Virgin Air 
Airbus A340; 
Number of air passengers: N/A. 

Date: May 26, 2007; 
Location: San Francisco International; 
Airline(s) and aircraft involved: Republic Airlines Embraer 170 and 
Skywest Airlines Embraer 120; 
Number of air passengers: 27. 

Date: July 11, 2007; 
Location: Fort Lauderdale-Hollywood International, FL; 
Airline(s) and aircraft involved: Delta Air Lines Boeing 757 and United 
Airlines Airbus A320; 
Number of air passengers: 172. 

Date: July 19, 2007; 
Location: Chicago O'Hare International; 
Airline(s) and aircraft involved: United Airlines Boeing 737 and US 
Airways Boeing 737; 
Number of air passengers: N/A. 

Date: August 16, 2007; 
Location: Los Angeles International; 
Airline(s) and aircraft involved: WestJet Boeing 737 and Northwest 
Airlines Airbus A320; 
Number of air passengers: 296. 

Date: December 2, 2007; 
Location: Baltimore-Washington International; 
Airline(s) and aircraft involved: US Airways/America West Airbus A320 
and Comair Canadair CRJ-100; 
Number of air passengers: N/A. 

Date: December 6, 2007; 
Location: Newark Liberty International; 
Airline(s) and aircraft involved: Continental Airlines Boeing 737 and 
Continental Express Embraer E145; 
Number of air passengers: N/A. 

Source: GAO analysis of FAA and NTSB data. 

Note: N/A indicates that the information was not contained in the 
National Transportation Safety Board (NTSB) incident reports. 

[End of table] 

Table 4: Total Number of Incursions and Number of Serious Incursions 
Involving at Least One Commercial Aircraft, Fiscal Year 2001 through 
Fiscal Year 2007: 

Fiscal year: 2001; 
Serious incursions: 53; 
Serious incursions involving at least one commercial aircraft: 26. 

Fiscal year: 2002; 
Serious incursions: 37; 
Serious incursions involving at least one commercial aircraft: 11. 

Fiscal year: 2003; 
Serious incursions: 32; 
Serious incursions involving at least one commercial aircraft: 9. 

Fiscal year: 2004; 
Serious incursions: 28; 
Serious incursions involving at least one commercial aircraft: 9. 

Fiscal year: 2005; 
Serious incursions: 29; 
Serious incursions involving at least one commercial aircraft: 9. 

Fiscal year: 2006; 
Serious incursions: 31; 
Serious incursions involving at least one commercial aircraft: 10. 

Fiscal year: 2007; 
Serious incursions: 24; 
Serious incursions involving at least one commercial aircraft: 8. 

Source: FAA. 

[End of table] 

Table 5: U.S. Airports that Experienced the Most Runway Incursions from 
Fiscal Year 2001 through Fiscal Year 2007: 

Airport: Los Angeles International; 
Number of serious incursions: 10; 
Number of total incursions: 55. 

Airport: Chicago O'Hare International; 
Number of serious incursions: 9; 
Number of total incursions: 55. 

Airport: North Las Vegas, Las Vegas, NV; 
Number of serious incursions: 5; 
Number of total incursions: 48. 

Airport: Hartsfield-Jackson Atlanta International; 
Number of serious incursions: 3; 
Number of total incursions: 41. 

Airport: John Wayne-Orange County, Santa Ana, CA; 
Number of serious incursions: 0; 
Number of total incursions: 41. 

Airport: Philadelphia International; 
Number of serious incursions: 2; 
Number of total incursions: 40. 

Airport: Long Beach-Daugherty Field, CA; 
Number of serious incursions: 2; 
Number of total incursions: 36. 

Airport: Boston Logan International; 
Number of serious incursions: 2; 
Number of total incursions: 36. 

Airport: Dallas-Ft. Worth International; 
Number of serious incursions: 3; 
Number of total incursions: 35. 

Airport: Phoenix Sky Harbor International; 
Number of serious incursions: 4; 
Number of total incursions: 31. 

Airport: Lambert-St. Louis International; 
Number of serious incursions: 2; 
Number of total incursions: 30. 

Airport: Las Vegas McCarran International; 
Number of serious incursions: 1; 
Number of total incursions: 30. 

Airport: Newark Liberty International; 
Number of serious incursions: 3; 
Number of total incursions: 25. 

Airport: General Mitchell International, Milwaukee, WI; 
Number of serious incursions: 1; 
Number of total incursions: 25. 

Airport: Minneapolis-St. Paul International; 
Number of serious incursions: 0; 
Number of total incursions: 25. 

Airport: Teterboro, NJ; 
Number of serious incursions: 3; 
Number of total incursions: 23. 

Airport: Miami International; 
Number of serious incursions: 3; 
Number of total incursions: 22. 

Airport: Ted Stevens Anchorage International; 
Number of serious incursions: 0; 
Number of total incursions: 22. 

Airport: Reno-Tahoe International, NV; 
Number of serious incursions: 1; 
Number of total incursions: 20. 

Airport: Cleveland Hopkins International; 
Number of serious incursions: 1; 
Number of total incursions: 20. 

Source: FAA. 

Note: Information was compiled from a list of airports that experienced 
20 or more incursions from fiscal year 2001 through fiscal year 2007 
and were certificated under 14 CFR Part 139. This information expands 
upon the information we presented in GAO-08-29 (fig. 4), which only 
included the top 10 airports experiencing incursions from 2001-2006. In 
addition, we now include three airports--Long Beach-Daugherty Field, 
John Wayne-Orange County, and North Las Vegas--which were previously 
identified as general aviation airports. 

[End of table] 

Table 6: Airports with Airport Surface Detection Equipment Model 3 
(ASDE-3)/Airport Movement Area Safety Systems (AMASS) or the Airport 
Surface Detection Equipment, Model X (ASDE-X) or Scheduled to Receive 
ASDE-X: 

Airport: Baltimore Washington International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: April 2010. 

Airport: Boston Logan International; 
ASDE-3/AMASS: ï¿½; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: July 2009. 

Airport: Bradley International, Windsor Locks, CT; 
ASDE-3/AMASS: [Empty]; 
ASDE-X commissioned: Check; 
Scheduled ASDE-X deployment[A]: . 

Airport: Camp Springs Andrews Air Force Base; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: . 

Airport: Charlotte Douglas International; 
ASDE-3/AMASS: [Empty]; 
ASDE- X commissioned: Check; 
Scheduled ASDE-X deployment[A]: [Empty]. 

Airport: Chicago Midway; 
ASDE-3/AMASS: [Empty]; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: June 2010. 

Airport: Chicago O'Hare International; 
ASDE-3/AMASS: [Empty]; 
ASDE-X commissioned: Check; 
Scheduled ASDE-X deployment[A]: [Empty]. 

Airport: Cleveland Hopkins International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: . 

Airport: Covington/Cincinnati Northern Kentucky International; 
ASDE-3/ AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: [Empty]. 

Airport: Dallas-Ft. Worth International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: April 2010. 

Airport: Denver International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: November 2009. 

Airport: Detroit Metro Wayne County; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: June 2008. 

Airport: Ft. Lauderdale-Hollywood International, FL; 
ASDE-3/AMASS: [Empty]; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: April 2009. 

Airport: General Mitchell International, Milwaukee, WI; 
ASDE-3/AMASS: [Empty]; 
ASDE-X commissioned: Check; 
Scheduled ASDE-X deployment[A]: [Empty]. 

Airport: George Bush Intercontinental, Houston, TX; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: November 2009. 

Airport: Hartsfield-Jackson Atlanta International; 
ASDE-3/AMASS: [Empty]; 
ASDE-X commissioned: Check; 
Scheduled ASDE-X deployment[A]: . 

Airport: Honolulu International-Hickam Air Force Base; 
ASDE-3/AMASS: [Empty]; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: May 2010. 

Airport: John F. Kennedy International, New York, NY; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: August 2008. 

Airport: John Wayne-Orange County, Santa Ana, CA; 
ASDE-3/AMASS: [Empty]; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: February 2010. 

Airport: Kansas City International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: . 

Airport: Lambert-St. Louis International; 
ASDE-3/AMASS: [Empty]; 
ASDE- X commissioned: Check; 
Scheduled ASDE-X deployment[A]: . 

Airport: Las Vegas McCarran International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: December 2009. 

Airport: Los Angeles International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: June 2009. 

Airport: Louis Armstrong New Orleans International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: . 

Airport: Louisville International-Standiford Field; 
ASDE-3/AMASS: [Empty]; 
ASDE-X commissioned: Check; 
Scheduled ASDE-X deployment[A]: [Empty]. 

Airport: Memphis International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: April 2011. 

Airport: Miami International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: March 2010. 

Airport: Minneapolis-St. Paul International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: March 2010. 

Airport: New York LaGuardia; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: December 2010. 

Airport: Newark Liberty International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: July 2009. 

Airport: Orlando International; 
ASDE-3/AMASS: [Empty]; 
ASDE-X commissioned: Check; 
Scheduled ASDE-X deployment[A]: . 

Airport: Philadelphia International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: December 2009. 

Airport: Phoenix Sky Harbor International; 
ASDE-3/AMASS: [Empty]; 
ASDE- X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: December 2008. 

Airport: Pittsburgh International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: . 

Airport: Portland International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: . 

Airport: Ronald Reagan Washington National; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: June 2010. 

Airport: Salt Lake City International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: May 2010. 

Airport: San Diego International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: August 2010. 

Airport: San Francisco International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: . 

Airport: Seattle-Tacoma International; 
ASDE-3/AMASS: [Empty]; 
ASDE-X commissioned: Check; 
Scheduled ASDE-X deployment[A]: . 

Airport: Ted Stevens Anchorage International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: . 

Airport: Theodore Francis Green State, Providence, RI; 
ASDE-3/AMASS: [Empty]; 
ASDE-X commissioned: Check; 
Scheduled ASDE-X deployment[A]: . 

Airport: Washington Dulles International; 
ASDE-3/AMASS: Check; 
ASDE-X commissioned: [Empty]; 
Scheduled ASDE-X deployment[A]: July 2008. 

Airport: William P. Hobby, Houston, TX; 
ASDE-3/AMASS: [Empty]; 
ASDE-X commissioned: Check; 
Scheduled ASDE-X deployment[A]: . 

Source: FAA. 

[A] Represents when the facility first declares the system ready for 
conditional use. Once the system is formally accepted by the facility, 
the system is commissioned. FAA's draft accelerated schedule, shown in 
this table, targets completing ASDE-X deployment by the Fall of 2010, 
with the exception of the New York LaGuardia and Memphis International 
airports, where the agency is coordinating ASDE-X implementation with 
the completion of new air traffic control towers. 

Note: As indicated above, 28 airports currently have ASDE-3/AMASS. Six 
additional airports (Seattle-Tacoma International, Lambert St.-Louis 
International, Hartsfield-Jackson Atlanta International, Louisville 
International-Standiford Field, Chicago O'Hare International, and 
Charlotte Douglas International) originally had ASDE-3/AMASS, but the 
equipment has since been upgraded to ASDE-X. 

[End of table] 

Table 7: Air Traffic Control Facilities with 20 Percent or More 
Employees Working 6-Day Weeks from February through May 2007: 

Facility: Hartsfield-Jackson Atlanta International; 
Average percentage of controllers working 6-day weeks: 52.09; 
Average percentage of controllers who volunteered to work overtime: 85. 

Facility: Long Beach-Daugherty Field, CA; 
Average percentage of controllers working 6-day weeks: 44.01; 
Average percentage of controllers who volunteered to work overtime: 27. 

Facility: Atlanta Terminal Radar Approach Control (TRACON); 
Average percentage of controllers working 6-day weeks: 42.65; 
Average percentage of controllers who volunteered to work overtime: 48. 

Facility: Shreveport Regional, LA; 
Average percentage of controllers working 6-day weeks: 40.94; 
Average percentage of controllers who volunteered to work overtime: 83. 

Facility: Jacksonville International, FL; 
Average percentage of controllers working 6-day weeks: 39.77; 
Average percentage of controllers who volunteered to work overtime: 66. 

Facility: Daytona Beach International, FL; 
Average percentage of controllers working 6-day weeks: 39.62; 
Average percentage of controllers who volunteered to work overtime: 65. 

Facility: Helena Regional, MT; 
Average percentage of controllers working 6-day weeks: 38.89; 
Average percentage of controllers who volunteered to work overtime: 
100. 

Facility: Buchanan Field, Concord, CA; 
Average percentage of controllers working 6-day weeks: 34.64; 
Average percentage of controllers who volunteered to work overtime: 
100. 

Facility: Boise, ID; 
Average percentage of controllers working 6-day weeks: 33.39; 
Average percentage of controllers who volunteered to work overtime: 81. 

Facility: Orlando International; 
Average percentage of controllers working 6-day weeks: 32.53; 
Average percentage of controllers who volunteered to work overtime: 30. 

Facility: Blue Grass, Lexington, KY; 
Average percentage of controllers working 6-day weeks: 32.38; 
Average percentage of controllers who volunteered to work overtime: 90. 

Facility: Ft. Lauderdale-Hollywood International, FL; 
Average percentage of controllers working 6-day weeks: 31.12; 
Average percentage of controllers who volunteered to work overtime: 65. 

Facility: Palm Beach International, West Palm Beach, FL; 
Average percentage of controllers working 6-day weeks: 30.87; 
Average percentage of controllers who volunteered to work overtime: 61. 

Facility: Reno-Tahoe International, NV; 
Average percentage of controllers working 6-day weeks: 29.01; 
Average percentage of controllers who volunteered to work overtime: 65. 

Facility: Camarillo, CA; 
Average percentage of controllers working 6- day weeks: 29.00; 
Average percentage of controllers who volunteered to work overtime: 43. 

Facility: Ted Stevens Anchorage International; 
Average percentage of controllers working 6-day weeks: 28.66; 
Average percentage of controllers who volunteered to work overtime: 58. 

Facility: Nashville International; 
Average percentage of controllers working 6-day weeks: 28.63; 
Average percentage of controllers who volunteered to work overtime: 75. 

Facility: Las Vegas TRACON; 
Average percentage of controllers working 6-day weeks: 27.66; 
Average percentage of controllers who volunteered to work overtime: 49. 

Facility: Bradley International, Windsor Locks, CT; 
Average percentage of controllers working 6-day weeks: 26.98; 
Average percentage of controllers who volunteered to work overtime: 62. 

Facility: Monroe Regional, LA; 
Average percentage of controllers working 6-day weeks: 26.90; 
Average percentage of controllers who volunteered to work overtime: 82. 

Facility: Sioux Gateway, IA; 
Average percentage of controllers working 6-day weeks: 26.83; 
Average percentage of controllers who volunteered to work overtime: 0. 

Facility: Los Angeles International; 
Average percentage of controllers working 6-day weeks: 25.73; 
Average percentage of controllers who volunteered to work overtime: 53. 

Facility: Phoenix TRACON; 
Average percentage of controllers working 6- day weeks: 24.77; 
Average percentage of controllers who volunteered to work overtime: 75. 

Facility: George Bush Intercontinental Houston, TX; 
Average percentage of controllers working 6-day weeks: 23.28; 
Average percentage of controllers who volunteered to work overtime: 97. 

Facility: Southern California TRACON; 
Average percentage of controllers working 6-day weeks: 21.96; 
Average percentage of controllers who volunteered to work overtime: 64. 

Source: FAA. 

Note: Also represents facilities where 4 percent or greater of the 
employees' work hours were covered by overtime. 

[End of table] 

[End of section] 

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Footnotes: 

[1] Taxiways are routes that aircraft follow to and from runways. 

[2] GAO, Aviation Runway and Ramp Safety: Sustained Efforts to Address 
Leadership, Technology, and Other Challenges Needed to Reduce Accidents 
and Incidents, GAO-08-29 (Washington, D.C.: Nov. 20, 2007). 

[3] ICAO's definition of an incursion is any occurrence at an airport 
involving the incorrect presence of an aircraft, vehicle, or person on 
the protected area of a surface designated for the landing or take-off 
of aircraft. Through September 2007, FAA defined a runway incursion as 
"any occurrence in the runway environment involving an aircraft, 
vehicle, person, or object on the ground that creates a collision 
hazard or results in a loss of required separation when an aircraft is 
taking off, intending to take off, landing, or intending to land." 

[4] Runway incidents that were classified as surface incidents can be 
serious, including an August 2006 crash of a Comair regional jet in 
Lexington, KY. That aircraft crashed after taking off on a runway that 
was too short for the aircraft, killing all but one of the 50 people 
aboard. FAA had defined a surface incident as any event where 
unauthorized or unapproved movement occurs within a movement area 
associated with the operation of an aircraft that affects or could 
affect the safety of flight. 

[5] FAA classifies the severity of runway incursions into four 
categories. FAA defines category A as separation decreases and 
participants take extreme action to narrowly avoid a collision, or the 
event results in a collision; category B, separation decreases and 
there is a significant potential for a collision; category C, 
separation decreases but there is ample time and distance to avoid a 
potential collision; and category D, there is little or no chance of 
collision. Category A and B incursions are considered serious. 

[6] AMASS is essentially the safety logic, which is designed to detect 
potential collisions, for ASDE-3. This combined technology is usually 
referred to as ASDE-3/AMASS. 

[7] FAA refers to ASDE-X as being commissioned after the system has 
been tested at an airport and demonstrated that the field site 
personnel can fully operate and maintain it. 

[8] According to FAA, the agency's ability to meet its accelerated 
ASDE- X deployment schedule depends on several factors such as the 
availability of funding and the cooperation of external organizations.

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