Following the second shootdown , Air Rhodesia created a system whereby the underside of the Viscounts would be coated with low @-@ radiation paint , with the exhaust pipes concurrently shrouded . According to tests conducted by the Air Force , a Viscount so treated could not be detected by the Strela 's targeting system once it was over 2 @,@ 000 feet ( 610 m ) . It were no further Viscount shootdowns in Rhodesia .