Federal Aviation Administration requirements for Runway Visual Range (RVR) visibility and ambient light sensors

The International Civil Aviation Organization (ICAO) provides guidance for the selection of sensors for use in Runway Visual Range (RVR) systems but does not define specific requirements for qualifying sensors. The United States (US) Federal Aviation Administration (FAA) has developed a specification for RVR systems that details specific visibility sensor (VS) and ambient light sensor (ALS) performance requirements and is in the process of procuring a new RVR system. This paper describes the scientific rationale behind this performance specification. This rationale is considered outside the scope of the specification itself.

The requirements include sensor type (forward scattermeter), calibration method, accuracy, measurement range, equal fog and snow response, calibration drift in 90 days, performance under severe snow conditions and practical requirements for use in the US National Airspace System (NAS), including a method of assuring that the scattering geometry has not changed significantly since leaving the factory.