AGA - 3.0 RUNWAY CHARACTERISTICS

3.1 Runway Length and Width

Runways are generally dimensioned to accommodate the aircraft considered to be the “critical aircraft” that is anticipated to utilize the runways most frequently. The “critical aircraft” is defined as being the aircraft type which the airport is intended to serve and which requires the greatest runway length. To identify the “critical aircraft”, flight manual performance data of a variety of aircraft are examined. Once the “critical aircraft” has been determined, the longest distance determined from analyzing both take-off and landing performance is used as the basis for runway dimensions. Generally, the runway width is increased to a maximum of 60 m as a function of length.

3.2 Graded Area

Each runway is bounded on the sides and ends by a prepared “graded” area. This graded area is provided to prevent catastrophic damage to aircraft leaving the runway sides and to protect aircraft that overfly the runway at very low altitudes during a balked approach for landing. The graded area at the end of the runway is not considered a normal stopway for accelerate-to-stop calculations. 

3.3 Displaced Runway Threshold

Occasionally, natural and human-made obstacles penetrate the obstacle limitation surfaces of the take-off and approach paths to runways.

To ensure that a safe clearance from these obstacles is maintained, it is necessary to displace the runway thresholds. In the case of runways for which instrument approach procedures are published in the CAP, the usable runway distances for landings and takeoffs are specified as declared distances. The displacements are also depicted on the aerodrome or airport diagram in both the CAP and the CFS. For other runways not having published CAP approaches, the requisite data is given in the CFS. Where a threshold is displaced, it is marked as shown in AGA 5.4.1.

When the portion of the runway before the displaced threshold is marked with displaced threshold arrows (see AGA 5.4.1), it is permissible to use that portion of the runway for taxiing, for takeoff and for the landing roll-out from the opposite direction. In addition, this displaced portion of the runway may be used for landing; however, it is the pilot’s responsibility to ensure that the descent path can be safely adjusted to clear all obstacles. When taking off from the end opposite to the displaced threshold, pilots should recognize the fact that there are obstacles present that penetrated above the approach slope to the physical end of the runway, which resulted in the threshold being displaced.

When a section of a runway is closed, either temporarily because of construction or permanently because the full length is no longer required, the closed portion of the runway will not be available for the surface movement of aircraft for taxiing, take-off or landing purposes and is marked with an “X”, indicating that the area is not suitable for aircraft use.

The closed portion of the runway may be shown on the aerodrome or airport diagram in the CFS and the CAP for identification purposes; however, declared distances will only include runway length starting at the new threshold position.

3.5 Pre-Threshold Area

A paved, non load-bearing surface that precedes a runway threshold is marked over the entire length with yellow chevrons, as shown in AGA 5.4.2, when its length exceeds 60 m.

3.6 Stopway

A stopway is a rectangular area on the ground at the end of the runway, in the direction of takeoff, prepared as a suitable area in which an aeroplane can be stopped in the case of an abandoned takeoff. It is marked over the entire length with yellow chevrons as shown in AGA 5.4.2 (when its length exceeds 60 m) and is lighted with red edge and end lights in the take-off direction. Its length is included in the ASDA declared for the runway.

3.7 Clearway

A clearway is a rectangular area above the ground or water selected as a suitable area over which an aeroplane may make a portion of its initial climb.

3.8 Declared Distances

The CAP provides declared distance information which is defined as follows:

(a) Take-off Run Available (TORA): The length of runway declared available and suitable for the ground run of an aeroplane taking off.

(b) Takeoff Distance Available (TODA): The length of the takeoff run available plus the length of the clearway, if provided.

NOTE: Maximum clearway length allowed is 300 m. The clearway length allowed must lie within the aerodrome or airport boundary.

(c) Accelerate Stop Distance Available (ASDA): The length of the takeoff run available plus the length of the stopway, where provided.

(d) Landing Distance Available (LDA): The length of runway which is declared available and suitable for the ground run of an aeroplane landing.

3.10 Runway and Taxiway Bearing Strength

The bearing strength of some aerodrome or airport pavement surfaces (runways, taxiways and aprons) to withstand continuous use by aircraft of specific weights and tire pressures has been assessed at specific locations. The TC Pavement Load Rating (PLR) and ICAO Pavement Classification Number (PCN) define the weight limits at or below which the aircraft may operate on pavements without prior approval of the aerodrome or airport authority. The tire pressure and Aircraft Load Rating (ALR)/Aircraft Classification Number (ACN) must be equal to or less than the PLR/PCN figures published for each aerodrome or airport. Aircraft exceeding published load restrictions may be permitted limited operations following an engineering evaluation by the airport operator. Requests to permit such operations should be forwarded to the airport operator and include the type of aircraft, operating weight and tire pressure, frequency of proposed operation and pavement areas required at the aerodrome or airport.

3.10.1 Pavement Load Rating Charts

Operators requiring information respecting aircraft weight limitations in effect at an aerodrome or airport can contact the airport operator.