A Belavia Boeing 737-800, registration EW-437PA performing flight B2-974 from Zhukovsky (Russia) to Minsk (Belarus), was climbing through FL170 out of Zhukovsky when the passenger oxygen masks were released and the crew initiated a rapid descent back to FL120 due to problems with the cabin pressure. The aircraft burned off fuel and landed safely back in Zhukovsky about 75 minutes after departure.

Passengers reported the oxygen masks were released and a burning odour developed in the cabin shortly after departure.