An Air Zimbabwe Boeing 737-200, registration Z-WPB performing flight UM-467 from Harare (Zimbabwe) to Johannesburg (South Africa), was enroute near Bulawayo (Zimbabwe) when the aircraft suffered the loss of cabin pressure, the passenger oxygen masks were released, prompting the crew to initiate an emergency descent and divert to Bulawayo for a safe landing. A replacement Airbus A320-200 registration Z-WPN was dispatched to Bulawayo as flight UM-9415, continued the flight and reached Johannesburg with a delay of 4.5 hours.