Runway Visual Range (RVR) is the horizontal distance a pilot can see on the runway. It is affected by the atmospheric conditions, by the background illumination, and by the quality of the runway lighting. An airport control tower reports the RVR to incoming flights. If the reported RVR is large enough, and if the pilot can see the runway lights at his minimum decision height at the start of the final approach then he proceeds with the landing, but if not then he will divert elsewhere. Many airports have systems for estimating the RVR, based on standardised values. More advanced methods involve measuring light transmission on the runway and the ambient light level. If RVR is underestimated, a pilot may be ordered land elsewhere even though landing would in fact have been safe. By analysing data from Birmingham Airport, the Study Group was able to quantify, in terms of airport throughput, the benefit of using measured light intensities compared to the standardised values.

Problem presented by
Vernon Taylor, TMS Photometrics

Study Group contributors
Tim Gardener (Industrial Mathematics KTN)
Jens Gravesen (Technical University of Denmark)
David Hewett (University of Oxford)
David Szotten (University of Manchester)
Phil Townsend (University of Bath)