Safety Target: Runway Incursions

by Don Côté, Procedures Specialist, Air Traffic Services, NAV CANADA

Editor’s Note: This article follows-up on another major article on runway incursions, which we published in the last issue of the Aviation Safety Letter. This is part of our ongoing Incursion Prevention Action Team (IPAT) awareness campaign, and provides the reader with a NAV CANADA perspective on the issue.

Safety officials in both the United States and Canada have identified the risk associated with runway incursions as one of the most urgent issues facing the aviation community today. Studies have shown that in spite of years of professional training, pilots, airport vehicle operators, air traffic controllers and flight service specialists continue to unwittingly find themselves involved in runway incursion incidents.

Most people in the aviation industry feel they know what a runway incursion is, claiming “I know one when I see one.” Until recently, though, no official definition could be found within Transport Canada or NAV CANADA. By implementing the recommendations from two separate studies on runway incursions, both Transport Canada and NAV CANADA adopted the following definition: Any occurrence at an airport involving the unauthorized or unplanned presence of an aircraft, vehicle, or person on the protected area of a surface designated for aircraft landings and departures.

How does a runway incursion happen? In 1987, the Canadian Aviation Safety Board (now the Transportation Safety Board of Canada (TSB)) issued a report entitled Report on a Special Investigation into the Risk of Collisions Involving Aircraft on or Near the Ground at Canadian Civil Airports. It stated “Both the Canadian and U.S. experience would suggest an extremely wide range of cause-related factors for the occurrences already examined which involve actual or potential ground conflicts. Unexpected human behavior is by far the most commonly recurring theme in these occurrences.”

On March 12, 1997, an airport controller cleared a Swearingen Metro to land with a Canadair Regional Jet holding in position on the runway. Reported visibility was ¾ mi. in snow showers, with vertical visibility of 1200 ft. Descending through 200 ft AGL, the Metro crew observed the aircraft on the runway and executed a missed approach. The TSB determined that a risk of collision occurred as the result of an ineffective controller handover procedure.

Two months earlier, another controller issued take-off clearance to an ATR-42. Visibility was ½ mi. in snow and blowing snow, with vertical visibility of 600 ft. Five minutes earlier six snow removal vehicles entered the runway without clearance. At rotation speed, the crew of the ATR-42 observed the vehicles on the runway, pitched the aircraft nose up to a steeper-than-normal attitude and flew over the vehicles at an altitude between 200 and 300 ft. In its report on the ATR incident, the TSB wrote “The following factors contributed to this dangerous situation: visibility was considerably restricted; and the local snow removal orders caused confusion” (emphasis added). The source of this confusion was a requirement in the local snow removal orders for the control tower to advise maintenance personnel when the runway was available for snow removal. The leader of the snow removal team incorrectly interpreted the term available as permission to enter the runway, without asking for authorization from the ground controller. These procedures have since been changed to prevent a repeat of the occurrence.

Since 1990, four runway incursions in the U.S. have killed 45 passengers and crew. The worst aircraft accident in history killed 583 passengers and crew when two B747s collided in fog on a runway in Tenerife, Canary Islands, in 1977. In 1978, 38 passengers and crew were killed in Cranbrook, B.C., when a B737 crashed and burst into flames trying to avoid a snowplow on the runway. At a 1998 workshop on runway incursions in Washington, the Executive Director of the Aircraft Owners and Pilots Association (AOPA) Safety Foundation commented on the general aviation (GA) involvement by noting that while the incursions tended to involve GA aircraft in conditions of good visibility, the accidents involve commercial aircraft at night or in conditions of poor visibility. The four fatal crashes in the U.S. in the 1990s, and the Cranbrook and Tenerife crashes all fit this profile.

The 1987 Canadian Aviation Safety Board Special Investigation contained 28 recommendations for areas such as scanning techniques for controllers, airport signage and markings, mandatory readbacks of ATC instructions, pilot training and safety promotion. Many of the recommendations have been implemented.

• Airport signs are better now than they were 12 years ago.
• The Mandatory Frequency Order was put in place to establish mandatory communication procedures at uncontrolled aerodromes.
• Flight service specialists were given authority to provide vehicle control service.
• Direction was issued to pilots through the A.I.P. to read back hold short instructions.

And yet, runway incursions happen in Canada at a rate of four to five each week. Canadian and Federal Aviation Administration (FAA) officials have raised the alarm with respect to runway incursions and the apparent inability to stem the steady increase in the number of incursions each year. In Canada, incursions have risen steadily from 60 in 1997 to 279 reported cases in 2000.

Good analysis requires good data.

Current NAV CANADA data on runway incursions comes from a variety of sources and, until recently, it has been difficult to make year-to-year comparisons with the available data. In 1999, however, detailed statistics on runway incursions gathered by NAV CANADA enabled authorities to determine exact incursion figures and design incursion prevention strategies.

With the introduction of a common definition, Transport Canada and NAV CANADA have also adopted identical terms to classify runway incursions. The following terms are used for the classification of incursions by type:

• OI: Incursions that occur as the result of actions taken by a controller or flight service specialist. Safety may have been jeopardized or less than the appropriate separation minima may have existed in these cases.
• PD: Pilot deviation.
• VPD: Vehicle/pedestrian deviation.

The following table lists the number and types of incursions recorded by NAV CANADA over the last four years. It is possible that the noticeable increase in incursion numbers is the result of an increased awareness of the incursion problem by air traffic service (ATS) personnel and pilots.

What is being done to reduce the number of runway incursions?

1. Transport Canada created the Sub-committee on Runway Incursions to study the Canadian incursion phenomenon; its final report was produced in Sept. 2000.
2. NAV CANADA created its own incursion-prevention committee to provide senior management with recommendations for the prevention of runway incursions.
3. Daily monitoring of incursions and statistical information gathering was initiated by NAV CANADA.
4. Discussions were held across the country with local stakeholders during site visits organized by NAV CANADA.

5. A safety bulletin was issued by NAV CANADA providing controllers and flight service specialists with an incursion alert.

6. Controllers and flight service specialists received recurrent training aimed at incursion prevention.
7. Transport Canada and NAV CANADA developed separate runway incursion action plans and are working on the joint implementation of common recommendations.

The current rate and number of runway incursions is unacceptable and remains a very serious concern for all and a risk that must be addressed. Although less than 15% of runway incursions are directly attributable to controllers or specialists, we know that emphasis on better scanning, position relief briefings and precise communication will help to reduce runway incursions — including those caused by pilot errors. It is also known that a significant number of pilot and vehicle deviations can be attributed to misunderstandings of control clearances, instructions and restrictions. Controllers and flight service specialists have been asked to help in several key areas:

• The readback — Many runway incursions involved the incorrect or missing readbacks of hold-short instructions. It is mandatory for the controller or flight service specialist to obtain a readback of any hold or hold-short instruction.
• Ground taxi — During taxi and before takeoff, pilots must go through checklists, copy clearances, enter flight management system (FMS) data, and communicate with cabin crew and dispatchers. After landing, most of the same activity goes on again. Controllers and flight service specialists should limit their attempts at communication with the aircraft during these periods unless absolutely necessary.
• Use of memory aids — Controllers have looked past cocked strips, alert strips and red lights intended to serve as defense mechanisms. Future recurrent training is expected to address this issue.
• Use of position relief checklists — The TSB described the risk of collision at another airport as “. . . the result of an ineffective controller handover procedure.” Position relief briefings were also identified causes in two other fact-finding boards and will be addressed in the next recurrent training year.
• Scanning techniques — Controllers and flight service specialists have explicit instructions to scan the runways and other controlled surfaces at all times. In addition, recurrent training will also cover this subject.
• Use of cleared-on-the-field clearances for airport service vehicles — These authorizations should be avoided. In more than one instance, the controller completely forgot about the vehicle on the runway when issuing a landing or take-off clearance to an aircraft.

A recent NAV CANADA study into runway incursions suggested that the management of the risk associated with runway incursions rests with the entire aviation community and not only the service providers such as NAV CANADA. The one recurring theme heard throughout this study was a call for a partnership between federal agencies, the aviation community and NAV CANADA.