Canadian Runway Friction (CRFI)

Landing distances and crosswind limitations (if applicable) contained in the aircraft flight manual (AFM) are demonstrated in accordance with specified performance criteria on runways that are bare, dry, and that have high surface friction characteristics. Unless some factor has been applied, these distances are only valid under similar runway conditions. Whenever a contaminant – such as water, snow or ice – is introduced to the runway surface, the effective coefficient of friction between the aircraft tire and runway is substantially reduced. The landing distance will increase and a crosswind may present directional control difficulties.

The average of the runway friction as measured by a decelerometer on runways with freezing or frozen contaminants is defined as the Canadian Runway Friction Index (CRFI). The decelerometer is an instrument mounted in a test vehicle that measures the decelerating forces acting on the vehicle when the brakes are applied. The instrument is graduated in increments from 0 to 1, the highest number being equivalent to the theoretical maximum decelerating capability of the vehicle on a dry surface. Small numbers represent low braking coefficients of friction while numbers on the order of 0.8 and above indicate the braking coefficients to be expected on bare and dry runways.

When available, a CRFI reading will be issued along with the runway surface condition in order to provide an overall descriptive picture of the runway condition and to quantify braking action. The CRFI is to be reported whenever:

  • There is ice or frost on the runway
  • There is wet ice on the runway
  • There is slush over the ice on the runway
  • Sand, aggregate material, anti-icing or de-icing chemicals are applied to the runway
  • There is a chemical solution on the ice on the runway
  • There is compacted snow on the runway
  • There is dry snow not exceeding a depth of 2.5 cm on the runway
Expected Range of CRFI by Surface Type
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