Canadian Aviation Regulations

602.131 (1) When no reading from RVR “A” or RVR “B” for the runway of intended approach is available, runway visibility is assessed

• (a) by a pilot holding an instrument rating and in the manner set out in section 622.131 of Standard 622 — Pilot Assessment of Runway Visibility Standards of the General Operating and Flight Rules Standards; or

• (b) by a person qualified in accordance with section 804.26 and in the manner set out in section 804.25.

(2) The assessment of runway visibility is valid only for a period of 20 minutes after it is established.