Page:CAB Accident Report, Western Air Lines Flight 221.pdf/13

 additional transmissometers may be located on other portions of the runway for the purpose of providing more representative reports.

Moreover, on airports equipped with one or more RVR installations, a ten-minute mean of RVR values of all runways reporting RVR is contained in the hourly weather sequence reports. This is shown on the sequence report as a Visual Range and is given in feet. This value does not pertain to, nor control operations on any individual runway but is given as an information item to assist in the overall appraisal of airport conditions. It is anticipated that the highest and the lowest one-minute value recorded during this period will also be given, together with the ten minute average.

Also, it is planned that RVR equipment will serve all runways equipped with an instrument landing system, and takeoff runways where deemed necessary. All presently installed Runway Visibility Systems will be converted to Runway Visual Range Systems as soon as computers and digital readout equipment become available.

BY THE CIVIL AERONAUTICS BOARD:

/s/ Chairman

/s/ Vice Chairman

/s/ Member

/s/ Member

CHAN GURNEY, Member, did not take part in the adoption of this report.