Aviation | Runway

Runway Length and Width

Runways are generally dimensioned to accommodate an aircraft considered to be the critical aircraft.

“the aircraft identified as having the
most demanding operational requirements with respect to
the determination of movement area dimensions, and other
aerodrome physical characteristics at the aerodrome or
part thereof”

To identify the critical aircraft, flight manual performance data of a variety of aircraft is examined. Once the critical aircraft has been determined, the longest distance
determined after analyzing both take-off and landing performance is used as the basis for runway dimensions. Generally, the runway width can be increased by a maximum of 60 m as a function of length.

Displaced Threshold Displacement

Occasionally, natural and human-made obstacles penetrate the obstacle limitation surfaces of the approach paths to runways. To ensure that a safe clearance from these obstacles is maintained, it is necessary to displace the threshold upwind from the adjacent runway end where the approach slope cannot be raised. In the case of runways for which instrument approach procedures (IAP) are published in the Canada Air Pilot (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 Canada Flight Supplement (CFS). For other runways
that do not have approaches published in the CAP, the requisite data is given in the CFS. Where a threshold is displaced, it is marked as,


When the portion of the runway preceding the threshold is marked with arrows (see AGA 5.4.1), it is permissible to use that portion of the runway for taxiing, takeoff, and landing roll-out from the opposite direction. When taking off from the end opposite the threshold, pilots should be aware of the fact that there are obstacles present that have penetrated above the approach slope leading to the physical end of the runway and have resulted in the threshold being displaced. In some cases, his may result in the publication of a specified climb and/or visibility.

Stop Way / Blast Pad

The paved area preceding a runway threshold prepared, maintained, and declared as a stopway is marked with yellow chevrons when its length exceeds 60 m. This area is not available for taxiing, the initial take-off roll, or the landing rollout. The chevron markings may also be used on blast pads.

A blast pad is defined in the Aerodrome Standards and Recommended Practices (TP 312) as “an area before the threshold that is prepared to resist erosion arising from jet
exhaust or propeller wash.” When over 60 m in length, this entire paved, non-load-bearing surface is marked with yellow chevrons.

Runway Markings

Runway markings vary depending on the runway’s length, width, surface type, and, if available, aircraft group number (AGN). They are described in detail in Transport Canada’s Aerodrome Standards and Recommended Practices (TP 312). Where an aiming point marking is provided, it is white and located at a specific distance from the threshold. Where touchdown zone (TDZ) markings are provided, they
are white and found in pairs. The location of pairs of TDZ markings is based on a horizontal spacing of 150 m. However, aiming point markings take precedence over TDZ markings; therefore, a pair of TDZ markings is omitted if it would otherwise fall
within 50 m of the aiming point marking

source: TC AIM

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