b. Operating Characteristics: If an aircraft or ground vehicle occupies an activation zone on the runway, the PAPI light fixtures on that runway will flash. The glide path indication is not affected, i.e. the configuration of red and white PAPI lights observed by the pilot on approach does not change. The stand-alone FAROS system flashes the PAPI lights when traffic occupies an activation zone whether or not there is an aircraft on approach. c. Pilot Observations: A pilot on approach to the runway observes the PAPI lights flashing if there is traffic on the runway activation zones and notices the PAPI lights cease to flash when the traffic moves outside the activation zones. A pilot on departure from the runway should disregard any observations of flashing PAPI lights. d. Pilot Actions: When a pilot observes a flashing PAPI at 500 feet above ground level (AGL), the pilot must look for and attempt to acquire the traffic on the runway. At 300 feet AGL, the pilot must contact ATC for resolution if the FAROS indication is in conflict with the clearance (see FIG 2-1-11). If the PAPI lights continue to flash and the pilot cannot visually determine that it is safe to land, the pilot must execute an immediate "go around". As with operations at non-FAROS airports, it is always the pilot"s responsibility to determine whether or not it is safe to continue with the approach and to land on the runway. FIG 2-1-11 FAROS Glide Slope Action Points Pilots should inform the ATCT when they have executed a go around due to a FAROS indication that is in conflict with ATC instructions. flashing lights (SFL) may be turned on and off. Some sequenced flashing light systems also have intensity control. NOTE- At this time, the stand-alone FAROS system is not widely implemented and is used for evaluation purposes. 2-1-9. Pilot Control of Airport Lighting 2-1-8. Control of Lighting Systems a. Operation of approach light systems and runway lighting is controlled by the control tower (ATCT). At some locations the FSS may control the lights where there is no control tower in operation. b. Pilots may request that lights be turned on or off. Runway edge lights, in-pavement lights and approach lights also have intensity controls which may be varied to meet the pilots request. Sequenced Airport Lighting Aids Radio control of lighting is available at selected airports to provide airborne control of lights by keying the aircraft"s microphone. Control of lighting systems is often available at locations without specified hours for lighting and where there is no control tower or FSS or when the tower or FSS is closed (locations with a part-time tower or FSS) or specified hours. All lighting systems which are radio controlled at an airport, whether on a single runway or multiple runways, operate on the same radio frequency. (See TBL 2-1-1 and TBL 2-1-2.) 2-1-11