Runway safety area
Encyclopedia
A runway safety area or runway end safety area (RESA) is defined as "the surface surrounding the runway
prepared or suitable for reducing the risk of damage to airplanes in the event of an undershoot, overshoot, or excursion from the runway."
Past standards called for the RSA to extend only 60m (200 feet) from the ends of the runway. Currently the international standard ICAO requires a 90m (300 feet) RESA starting from the end of the runway strip (which itself is 60m from the end of the runway), and recommends but not requires a 240m RESA beyond that. In the U.S., the recommended RSA may extend to 500 feet in width, and 1,000 feet beyond each runway end (according to U.S. Federal Aviation Administration
recommendations; 1000 feet is equivalent to the international ICAO-RESA of 240m plus 60m strip). The standard dimensions have increased over time to accommodate larger and faster aircraft, and to improve safety.
as a landing strip. Thereafter, the requirements of more advanced airplanes necessitated improving or paving the center portion of the landing strip. The term "landing strip" was retained to describe the graded area surrounding and upon which the runway or improved surface was constructed.
The primary role of the landing strip changed to that of a safety area surrounding the runway. This area had to be capable, under normal (dry) conditions, of supporting airplanes without causing
structural damage to the airplanes or injury to their occupants. Later, the designation of the area was changed to "runway safety area," to reflect its functional role. The runway safety area enhances the safety of airplanes which undershoot, overrun, or veer off the runway, and it provides greater accessibility for firefighting and rescue equipment during such incidents. One of the difficulties is that overshooting aircraft don't always leave the runway straight off the end at relatively slow speed; they leave from the side of the runway (like the Congonhas A320 incident), they leave off the end at such a high speed that they would overrun any safety area (like the AF358 A340 incident
in Toronto), or they land well short of the runway (like BA38 B777 incident
at Heathrow).
(FAA) recognized that incremental improvements inside standard RSA dimensions can enhance the margin of safety for aircraft. This is a significant change from the earlier concept where the RSA was deemed to end at the point it was no longer graded and constructed to standards. Previously, a modification to standards could be issued if the actual, graded and constructed RSA did not meet dimensional standards as long as an acceptable level of safety was provided.
Today, modifications to standards no longer apply to runway safety areas. Instead, FAA airport regional division offices are required to maintain a written determination of the best practicable alternative for improving non-standard RSAs. They must continually analyze the non-standard RSA with respect to operational, environmental, and technological changes and revise the determination as appropriate. Incremental improvements are included in the determination if they are practicable and they will enhance the margin of safety.
accident in Toronto
, the Transportation Safety Board of Canada
recommended changes to the runway safety areas on runways at Canadian airports.
TSB suggest airports need to employ EMAS
(engineered material arresting system) on Canadian runways by constructing a 300 m (as per ICAO standard of 60 m + 240 m or FAA 300 m) overrun at the end of all runways.
The EMAS can be of benefit where the aircraft leaves the runway neatly at the end, and there are several clear examples where it saved an aircraft from a serious accident. However EMAS is not without its own problems. It needs almost as much length as the RESA - an EMAS system designed to stop a Boeing 747 leaving the runway at 70 knots speed needs to be 183m long (which is not much less than the 240m for the RESA) . Any faster, and the aircraft overruns. And if an EMAS is damaged, it will require out of hours repair. This does not mean that the runway must be closed after an overrun, as the whole EMAS arrestor bed is still effective even if there are furrows left by tire tracks across a portion of the arrestor bed.
Runway
According to ICAO a runway is a "defined rectangular area on a land aerodrome prepared for the landing and take-off of aircraft." Runways may be a man-made surface or a natural surface .- Orientation and dimensions :Runways are named by a number between 01 and 36, which is generally one tenth...
prepared or suitable for reducing the risk of damage to airplanes in the event of an undershoot, overshoot, or excursion from the runway."
Past standards called for the RSA to extend only 60m (200 feet) from the ends of the runway. Currently the international standard ICAO requires a 90m (300 feet) RESA starting from the end of the runway strip (which itself is 60m from the end of the runway), and recommends but not requires a 240m RESA beyond that. In the U.S., the recommended RSA may extend to 500 feet in width, and 1,000 feet beyond each runway end (according to U.S. Federal Aviation Administration
Federal Aviation Administration
The Federal Aviation Administration is the national aviation authority of the United States. An agency of the United States Department of Transportation, it has authority to regulate and oversee all aspects of civil aviation in the U.S...
recommendations; 1000 feet is equivalent to the international ICAO-RESA of 240m plus 60m strip). The standard dimensions have increased over time to accommodate larger and faster aircraft, and to improve safety.
Historical development
In the early years of aviation, all airplanes operated from relatively unimproved airfields. As aviation developed, the alignment of takeoff and landing paths centered on a well defined area knownas a landing strip. Thereafter, the requirements of more advanced airplanes necessitated improving or paving the center portion of the landing strip. The term "landing strip" was retained to describe the graded area surrounding and upon which the runway or improved surface was constructed.
The primary role of the landing strip changed to that of a safety area surrounding the runway. This area had to be capable, under normal (dry) conditions, of supporting airplanes without causing
structural damage to the airplanes or injury to their occupants. Later, the designation of the area was changed to "runway safety area," to reflect its functional role. The runway safety area enhances the safety of airplanes which undershoot, overrun, or veer off the runway, and it provides greater accessibility for firefighting and rescue equipment during such incidents. One of the difficulties is that overshooting aircraft don't always leave the runway straight off the end at relatively slow speed; they leave from the side of the runway (like the Congonhas A320 incident), they leave off the end at such a high speed that they would overrun any safety area (like the AF358 A340 incident
Air France Flight 358
Air France Flight 358, a flight from Paris, France, to Toronto, Canada, using an Airbus A340 airliner, departed Paris without incident at 11:53 UTC 2 August 2005, later touching down on runway 24L-06R at Toronto Pearson International Airport at 20:01 UTC...
in Toronto), or they land well short of the runway (like BA38 B777 incident
British Airways Flight 38
British Airways Flight 38 was a scheduled flight from Beijing Capital International Airport which crash landed just short of the runway at its destination, London Heathrow Airport, on 17 January 2008 after an flight. There were no fatalities, but 47 people sustained injuries...
at Heathrow).
Recent changes in the United States
The U.S. Federal Aviation AdministrationFederal Aviation Administration
The Federal Aviation Administration is the national aviation authority of the United States. An agency of the United States Department of Transportation, it has authority to regulate and oversee all aspects of civil aviation in the U.S...
(FAA) recognized that incremental improvements inside standard RSA dimensions can enhance the margin of safety for aircraft. This is a significant change from the earlier concept where the RSA was deemed to end at the point it was no longer graded and constructed to standards. Previously, a modification to standards could be issued if the actual, graded and constructed RSA did not meet dimensional standards as long as an acceptable level of safety was provided.
Today, modifications to standards no longer apply to runway safety areas. Instead, FAA airport regional division offices are required to maintain a written determination of the best practicable alternative for improving non-standard RSAs. They must continually analyze the non-standard RSA with respect to operational, environmental, and technological changes and revise the determination as appropriate. Incremental improvements are included in the determination if they are practicable and they will enhance the margin of safety.
Warnings in Canada
From the aftermath of the Air France Flight 358Air France Flight 358
Air France Flight 358, a flight from Paris, France, to Toronto, Canada, using an Airbus A340 airliner, departed Paris without incident at 11:53 UTC 2 August 2005, later touching down on runway 24L-06R at Toronto Pearson International Airport at 20:01 UTC...
accident in Toronto
Toronto
Toronto is the provincial capital of Ontario and the largest city in Canada. It is located in Southern Ontario on the northwestern shore of Lake Ontario. A relatively modern city, Toronto's history dates back to the late-18th century, when its land was first purchased by the British monarchy from...
, the Transportation Safety Board of Canada
Transportation Safety Board of Canada
The Transportation Safety Board of Canada , officially the Canadian Transportation Accident Investigation and Safety Board is the agency of the Government of Canada responsible for maintaining...
recommended changes to the runway safety areas on runways at Canadian airports.
TSB suggest airports need to employ EMAS
Engineered Materials Arrestor System
An engineered materials arrestor system or engineered materials arresting system is a bed of engineered materials built at the end of a runway. Engineered materials are defined in FAA Advisory Circular No 150/5220-22A as "high energy absorbing materials of selected strength, which will reliably...
(engineered material arresting system) on Canadian runways by constructing a 300 m (as per ICAO standard of 60 m + 240 m or FAA 300 m) overrun at the end of all runways.
The EMAS can be of benefit where the aircraft leaves the runway neatly at the end, and there are several clear examples where it saved an aircraft from a serious accident. However EMAS is not without its own problems. It needs almost as much length as the RESA - an EMAS system designed to stop a Boeing 747 leaving the runway at 70 knots speed needs to be 183m long (which is not much less than the 240m for the RESA) . Any faster, and the aircraft overruns. And if an EMAS is damaged, it will require out of hours repair. This does not mean that the runway must be closed after an overrun, as the whole EMAS arrestor bed is still effective even if there are furrows left by tire tracks across a portion of the arrestor bed.