Originally Posted by
down3gr33ns
So if the RVR apparatus isn't certified for smoke, what prevents an ARO going out and counting the lights to assess the visibility? I'm told the METAR gave the visibility and, if so, how was that obtained?
Where I once worked that (counting the runway lights) was how the crew determined if they had the required visibility for takeoff in poor conditions at airports where there wasn't any RVR equipment. Determining if the required visibility existed or otherwise was the crew's responsibility and counting the visible lights and multiplying the number seen by the known spacing got you the answer.
Doesn't an assessment of the visibility fall within the role of an accredited met observer?
Nothing prevents anyone from making a realistic assessment of the visibility. It’s just that for low vis ops e.g. SA CAT I and CAT II in Canberra, RVR is REQUIRED. It CANNOT be replaced by RV assessed by pilot or other observer (e.g. counting runway lights). Also, from what we have been told, it’s not just that the RVRs are not certified in smoke, they have also been giving false readings, see below.
RVR AT YSCB MAY BE UNAVAILABLE DUE TO THE RVR EQUIPMENT IS DESIGNED FOR FG/BR - IT IS NOT RATED FOR FU AND HAS BEEN GIVING ERRONEOUS READINGS.
.
YSCB TWR IS ADDRESSING THIS ISSUE BY INDICATING RVR NOT AVBL ON THE ATIS AND SUPPLYING INSTEAD, A VISIBILITY ASSESSMENT.
.
NOTE - WITHOUT RVR INFORMATION, CAT II AND CAT I SA APPROACHES ARE NOT AVAILABLE.