What happened
On August 8, 1963, during a joint naval and air force training exercise known as Operation CAPEX, a Shackleton 1718 departed from Air Force Station Ysterplaat. The mission involved tracking a Royal Navy submarine near Port Elizabeth. Prior to departure, the flight crew had been specifically instructed by the Maritime Group to fly a seaward route over False Bay to avoid high icing levels and mountainous terrain expected on the overland path.
Despite these instructions and warnings regarding severe weather—including heavy rain, hail, and intense turbulence—the pilot elected to climb to 2,896 m (9,500 ft) and fly an overland route toward Port Elizabeth. During the flight, the aircraft experienced extreme atmospheric conditions. Evidence from the wreckage suggests that the airframe was subjected to loads exceeding its design limits. Components of the aircraft, including the port elevator, a section of the starboard rudder, and a port wingtip fuel tank, detached while in flight.
The pilot transmitted a "Mayday" signal at approximately 15:25, which coincided with the moment the aircraft lost control. The Shackleton 1718 impacted the ground in the Stettynskloof valley, resulting in 13 fatalities. The wreckage was discovered by aircrews two days later.
Findings
An investigation into the accident identified several contributing factors. The primary cause was the pilot's decision to deviate from the briefed flight path, choosing an overland route through mountainous terrain during periods of severe icing and heavy turbulence. This deviation placed the aircraft in a high-risk environment where aerodynamic forces were significantly increased.
Technical analysis revealed that the airframe suffered structural failure when subjected to intense loads. The presence of open fuel dump valves suggested the crew attempted to reduce the aircraft's weight to mitigate the effects of the turbulence. The investigation concluded that the combination of heavy icing, extreme wind speeds, and the high weight of the aircraft led to the disintegration of critical flight control surfaces, rendering the aircraft uncontrollable.