In March 1977, in what remains the world's deadliest aviation accident, two passenger jumbo jets collided on a runway at Tenerife, Canary Islands, causing the deaths of 583 passengers and crew. In the United States, the deadliest U.S. runway incursion accident occurred in August 2006 when Comair flight 5191, a regional jet, crashed after taking off from the wrong runway, killing 49 of the 50 people on board. The worst U.S. runway incursion accident involving two aircraft was a collision between a USAir 737 and a Skywest Metroliner commuter airplane at Los Angeles International Airport in February 1991, which killed 34 people.
A recent runway incursion illustrates the danger of these situations. On May 29, 2009, a runway incursion involving a PSA Airlines Canadair Regional Jet (CRJ)-200, and a Pilatus PC-12 occurred at the Charlotte/Douglas International Airport (CLT), Charlotte, North Carolina. There were 3 crewmembers and 43 passengers aboard the PSA CRJ-200 and two crewmembers and one passenger aboard the Pilatus. The local controller cleared the CRJ-200 aircraft for takeoff and, three seconds later, directed the Pilatus to taxi into position and hold on the active runway. The CRJ-200 aircraft was on takeoff roll when the pilots noticed the Pilatus approaching the left side of the runway. As the CRJ-200 continued to accelerate to approximately 85 knots, the Pilatus did not appear to be slowing down to hold short of the active runway. When it became apparent that the Pilatus was not going to hold short of the active runway, the CRJ-200 pilot initiated a rejected takeoff. Although the Airport Surface Detection Equipment Model X (ASDE-X) system alerted the local controller of the conflict, the CRJ-200 crew initiated the rejected takeoff before the local controller cancelled the takeoff clearance. The CRJ-200 aircraft came to a complete stop on the runway centerline. The crew estimated they missed colliding with the Pilatus by approximately 2-3 feet.
The runway incursion issue has been on the NTSB's Most Wanted List since its inception in 1990. In the late 1980s, an inordinate number of runway incursions/ground collision accidents resulted in substantial loss of life, and the NTSB issued numerous safety recommendations addressing the issue. The Federal Aviation Administration (FAA) has since taken action to inform controllers of potential runway incursions, improve airport markings, and install the Airport Movement Area Safety System (AMASS) and ASDE-X. These systems are an improvement but are not sufficient as designed to prevent all runway incursions.
Information needs to be provided directly to flight crews as expeditiously as possible to prevent runway incursions. The issue is one of reaction time. NTSB investigations have found that AMASS is not adequate to prevent serious runway collisions because too much time is lost routing valuable information through ATC. After an AMASS alert, the controller must determine the nature of the problem, determine the location, identify the aircraft involved, and determine what action to take. Only after all of these determinations have been made can appropriate warnings or instructions be issued. The flight crew must then respond to the situation and take action. Simulations of AMASS performance using data from actual incursions show that alerts may occur as little as 8 to 11 seconds before a potential collision. In incidents(1) such as the one described above, AMASS did not alert controllers in time to be effective, and the situations were instead resolved by flight crew actions that sometimes bordered on heroics or simple luck.
Until there is a system in place to positively control ground movements of all aircraft, with direct warning to pilots, the potential for this type of disaster will continue to be high.
ATC procedures should require specific clearances, rather than rely on implied clearances, for aircraft to cross runways. This requirement would reduce the chance of a runway incursion because pilots would have to obtain an explicit clearance before crossing any runway; without such a clearance, the pilot would be required to hold short. Further, if aircraft need to be cleared to cross multiple runways, controllers should issue an explicit crossing instruction for each runway after the previous runway has been crossed.
Implementation of the NTSB's recommendations will reduce the chances of a runway collision between two airplanes and will also reduce the risk of a pilot's mistakenly selecting an incorrect runway, as occurred in the August 27, 2006, Comair flight 5191 accident in Lexington, Kentucky. If the recommended revisions had been implemented before that accident, these procedures would have provided the flight crew with better awareness of the airplane's position along the taxi route and would have required the controller to visually observe the airplane's position and monitor the taxi as the airplane progressed toward the departure runway. In addition, research and analysis sponsored by the FAA has cited pilot and controller concerns about the adequacy of runway crossing requirements, and most of these pilots and controllers thought that it would be beneficial to adopt the procedures recommended. Also, if a moving map display or an automatic system to warn pilots when taking off from the wrong runway had been available, the pilots would likely not have made their catastrophic mistake.
Analysis performed by the Flight Safety Foundation has shown that runway excursions accounted for approximately 97 percent of all runway-related accidents involving commercial transport aircraft worldwide between 1995 and 2008.(2) A runway excursion occurs when an aircraft either overruns or undershoots a runway while landing or taking off. Existing FAA regulations do not specify either the type of arrival landing distance assessment that should be performed or a safety margin that should be applied. The FAA advocates a minimum safety margin of 15 percent for arrival landing distance assessments and a 15-percent factor is included in the European Aviation Safety Agency and Joint Airworthiness Authorities operational requirements for contaminated runway landing performance. The FAA has sought voluntary operator compliance with performing landing distance assessments and applying a 15-percent safety margin. However, runway overruns continue to occur in the United States when the flight crews have not performed a landing distance assessment before landing on a contaminated runway.
The FAA is currently evaluating three technologies to mitigate the risk of a runway incursion. These technologies include (1) runway status lights (RWSL), a visual alerting system utilizing in-pavement red lights that alert pilots and vehicle operators that it is unsafe to enter or begin a takeoff on a runway; (2) the final approach runway occupancy signal (FAROS) system, which flashes the precision approach path indicator (PAPI) lights to provide pilots on final approach a direct notification that the runway is occupied; and (3) the Low Cost Ground Surveillance (LCGS) Program, to provide basic ground traffic surveillance capability at small and medium airports where cost-effective deployment of ASDE-X technology is not possible.
Several years ago the FAA installed a test RWSL system at Dallas-Ft. Worth International Airport (DFW). This system has worked very well, and the FAA commissioned an additional RWSL test system at Los Angeles International Airport in June 2009. Another RWSL test system is being installed at Boston Logan Airport. Beginning in 2011, the FAA will initiate a program for national deployment of RWSL systems at 22 ASDE-X sites throughout the United States. The FAA completed two studies of FAROS systems evaluating whether flashing PAPI lights should be used, or if other types of warning lights on a runway would be more effective. The FAA found that the PAPI was as effective as the alternatives studied, and it is considerably less expensive and less complicated to install and maintain. DFW installed, and has been testing since September 2008, an enhanced version of the FAROS system, integrated with the RWSL. The FAA has not yet developed any plans for national deployment of FAROS systems. The FAA completed engineering and technical evaluations of two LCGS products and has initiated a pilot project to deploy LCGS products at several airports. The FAA intends to use the results of these pilot projects to develop requirements and an acquisition strategy for deployment of LCGS systems at additional airports.
In addition, in 2007 the FAA sponsored an industry-government working group through RTCA Special Committee 186 to develop an operational safety assessment (OSA) of surface alerting using Automatic Dependent Surveillance - Broadcast (ADS-B). The FAA believes that the OSA will lead to the development of a minimum operational performance specification for an ADS-B based surface alerting application that would provide a direct cockpit warning of a runway incursion risk.
The FAA is taking commendable actions, particularly in expanding the RWSL program to a number of airports. However, many of these systems are still being evaluated. In 2011, 11 years after the issuance of the recommendation for a direct warning to the cockpit, only 22 airports will have RWSLs installed. The FAA's plans to develop standards for a system based on ADS-B to provide a direct cockpit warning are also commendable, although the FAA's proposed requirements for ADS-B do not include a requirement for ADS-B In(3), which will be necessary for such a system.
The FAA held a "Call to Action" on August 15, 2007, at which key aviation industry representatives met for 1 day to discuss short- and long-term measures to improve the safety of airport operations. In January 2009, the FAA indicated that the analysis developed by its safety risk management panel had validated the changes proposed in Safety Recommendation A-00-67 and a slightly modified version of the changes proposed in Safety Recommendation A-00-68. The FAA is currently preparing a rulemaking to amend Section 91.129(i) to require that all runway crossings be authorized only by a specific air traffic control clearance. In addition, the FAA plans to revise Order 7110.65 to require that air traffic controllers issue an explicit clearance for all runway crossings. The revision will also prohibit clearances for multiple runway crossings; however, there will be an exception for closely spaced runways of less than 1,000 feet. The FAA anticipates implementing the changes to Order 7110.65 by June 2010. Nine years after the NTSB issued recommendations concerning taxi clearance procedures, and more than 2 years after the Call to Action meeting, at which these issues were identified as critical safety concerns, the NTSB is pleased to learn that the FAA is now initiating the recommended regulatory revisions.
The FAA announced that it is providing funding for users who agree to equip their aircraft with an Electronic Flight Bag, which includes Moving Map Displays, or an aural runway alerting system. The FAA's program to encourage users to equip their aircraft with moving map displays is commendable, but it is not a requirement, and the program is limited to no more than $5 million. As a result, the program is not likely to result in widespread adoption of moving map technology. FAA standards for this equipment, as well as commercial products and installations, are already available.
The NTSB's recommendation concerning landing distance assessments was issued as an Urgent recommendation on October 2, 2007. In the 2 1/2 years since then, the FAA developed a voluntary guidance document for performing landing distance assessments with a 15-percent safety margin. The FAA surveyed 14 Code of Federal Regulations Part121 operators and found that 92percent of U.S. airline passengers are now being carried by air carriers in full or partial compliance with the practices recommended. In October 2007, the FAA established a Takeoff/Landing Performance Assessment Aviation Rulemaking Committee (ARC) to review regulations affecting certification and operation of airplanes and airports for airplane takeoff and landing operations on contaminated runways. The ARC focused on turbine-powered aircraft including both turbojet and turboprop airplanes operated under parts 121, 135, 125, and 91 subpart K; its charter expired on October 12, 2009. The FAA is in the process of reviewing the ARC's recommendations. However, the NTSB continues to investigate runway overrun accidents for which landing distance assessments had not been conducted, but were necessary.(4) Considering these recent accidents, it appears that the FAA's guidance has not been effective.
Implement a safety system for ground movement that will ensure the safe movement of airplanes on the ground and provide direct warning capability to flight crews. Implement ATC procedures requiring an explicit clearance for each runway crossing. Require operators to install cockpit moving map displays or an automatic system that alerts pilots when a takeoff is attempted on a taxiway or a runway other than the one intended. Require operators to conduct arrival landing distance assessments before every landing based on existing performance data, actual conditions, and incorporating a minimum safety margin of 15 percent.
A-00-66 (FAA)
Issued July 6, 2000
Added to the Most Wanted List: 2001
Status: Open-Unacceptable Response
Require, at all airports with scheduled passenger service, a ground movement safety system that will prevent runway incursions; the system should provide a direct warning capability to flight crews. In addition, demonstrate through computer simulations or other means that the system will, in fact, prevent incursions. (Source: Recommendation letter to the FAA regarding runway incursions, July 6, 2000.)
A-00-67 (FAA)
Issued July 6, 2000
Added to the Most Wanted List: 2007
Status: Open-Acceptable Response
Amend 14 Code of Federal Regulations (CFR) Section 91.129(I) to require that all runway crossings be authorized only by specific air traffic control clearance, and ensure that U.S. pilots, U.S. personnel assigned to move aircraft, and pilots operating under 14 CFR Part 129 receive adequate notification of the change. (Source: Recommendation letter to the FAA regarding runway incursions, July 6, 2000.)
A-00-68 (FAA)
Issued July 6, 2000
Added to the Most Wanted List: 2007
Status: Open-Acceptable Response
Amend FAA Order 7110.65, "Air Traffic Control," to require that, when aircraft need to cross multiple runways, air traffic controllers issue an explicit crossing instruction for each runway after the previous runway has been crossed. (Source: (Source: Recommendation letter to the FAA regarding runway incursions, July 6, 2000.)
A-07-45 (FAA)
Issued August 28, 2007
Added to the Most Wanted List: 2008
Status: Open-Acceptable Response
Require that all 14 Code of Federal Regulations Part 91K, 121, and 135 operators install on their aircraft cockpit moving map displays or an automatic system that alerts pilots when a takeoff is attempted on a taxiway or a runway other than the one intended. (Source: Attempted Takeoff From Wrong Runway Comair Flight 5191 Bombardier CL-600-2B19, N431CA Lexington, Kentucky August 27, 2006. [NTSB/AAR-07-05])
A-07-57 (FAA)
Issued October 2, 2007 (Superseded A-06-16)
Added to the Most Wanted List: 2007
Status: Open-Unacceptable Response
Immediately require all 14 Code of Federal Regulations Part 121, 135, and 91 subpart K operators to conduct arrival landing distance assessments before every landing based on existing performance data, actual conditions, and incorporating a minimum safety margin of 15 percent. (Source: Runway Overrun and Collision Southwest Airlines Flight 1248 Boeing 737-74H, N471WN Midway Airport Chicago, Illinois, December 8, 2005. [NTSB/AAR-07-06])
