On 12 February 1979, in an attempt to assassinate Walls, ZIPRA shot down Air Rhodesia Flight 827 with a Soviet-made SAM-7 missile. Flight 827 was a regularly scheduled flight from Kariba to Salisbury. The aircraft was a Vickers Viscount known as "The Umniati", and the second civilian Viscount they had shot down. All 55 passengers and 4 crew on board were killed. But Walls and his wife had missed the flight and were aboard a second Viscount which took off 15 minutes later, and which landed unharmed at Salisbury. The Zimbabwe African People's Union leader Joshua Nkomo appeared on British domestic television laughing about this incident, declaring that Walls was responsible for the passengers' deaths because he was the "biggest military target", and this justified the action. The Rhodesian government responded to the attack by air-strikes on ZIPRA bases within the borders of Angola and Zambia.