What happened
On November 21, 2015, a flight operated by Avia Traffic Company, flying route AVJ 767-768 from Osh to Krasnoyarsk and back to Osh, was involved in a weather-related diversion. The aircraft, a Boeing 737-300 with registration EX-37005, departed Osh at 14:40 and arrived in Krasnoyarsk at 17:35. After refueling and boarding passengers, the aircraft departed Krasnoyarsk for the return leg to Osh at 19:34.
During the approach to Osh, at 22:48, the flight crew was notified by approach control that the weather conditions at the destination had deteriorated below landing minimums. The report indicated heavy fog with a runway visibility of 400 meters and a vertical visibility of 100 feet. Consequently, the crew descended from 8000 feet to divert to the alternate airport, Manas International Airport in Bishkek. The aircraft landed safely at Manas at 23:20.
The investigation
Following the diversion, the crew arrived at the Aerodrome Meteorological Center (AMC) at 23:56 to review the actual weather conditions and forecasts for Osh. The investigation noted that a SPECI report issued for Osh at 23:47 confirmed extremely poor visibility, with a recorded visibility of 150 meters and a runway visibility of 500 meters. The report also indicated light drizzle, fog, and a vertical visibility of only 100 feet (30 meters). The forecast for the upcoming hours suggested that visibility could temporarily drop as low as 100 meters.