BEA Flight 142 was en route from London to Naples flying on Airway Amber 1, reporting over Ostia, Italy, at 23500 feet at 11:44. The flight reported continuing to Ponza, estimating arrival over this NDB at 11:57. At 10:45 a formation of four Italian Air Force North American F-86E Sabre jets had taken off from Pratica di Mare Air Base on a group tactical training exercise in the Pratica CTR (West of Airway Amber 1) which was prohibited for civil aircraft. The formation was 5 km east of Anzio on a 310 degree heading carrying out a reverse attack manoeuvre consisting of an initial dive, followed by a climb turn to the right and a steep dive with final recovery to level flight. During the steep dive that followed the climbing turn, the leading aircraft collided with the Viscount. Both aircraft crashed, but the F-86 pilot was able to eject. PROBABLE CAUSE: “The accident was attributed to “an Act of God” – since neither of the pilots saw the other aircraft before they collided. A contributory cause of the accident was deviation of the Viscount from the airway which placed it in a prohibited area reserved for military activities.”