[4] On 14 September 1961, under the code name Checkmate, the NATO high command mobilised the air forces of France, Belgium, the Netherlands, Denmark, and West Germany for the purpose of an exercise.

[1] Shortly after, the pair were picked up by NATO radar stations near Warburg, in southern Westphalia, heading east, in the direction of Königs Wusterhausen, south of Berlin.

[1] It was only when reaching a position north of Leipzig, deep within East German air space, that Pfefferkorn sent a Mayday signal, which was picked up, to their surprise, by the French-controlled airport at Tegel in West Berlin, which gave them permission to land.

An airman in the Berlin Air Route Traffic Control Center ordered the two pilots not to turn around and face the pursuing fighter planes but instead to head for the Tegel airport as it had a longer runway than Tempelhof and was more suitable for jets.

[2] Because of the actions of this airman and the heavy cloud cover, which the two pilots used to conceal themselves, Pfefferkorn and Eberl escaped the pursuing Soviet aircraft and successfully landed their planes without further incident at Tegel.

[1] The then-West German Minister of Defence, Franz-Josef Strauß, apologised to the Soviet ambassador in Bonn for the incident, sending his secretary of state, Volkmar Hopf.

However, it chose to blame bad weather for the incident rather than the failure of its ground control to guide the Soviet fighter planes on to the West German ones.

[2] Another theory (which turned out to be true) held that the two aircraft were hidden by the French authorities at Tegel and, later, buried at the airfield, where they were accidentally rediscovered in the 1970s.

[8] Eleven months after the F-84 incident, the Soviet threat to shoot down any aircraft violating the border materialized when a Hawker Sea Hawk of the Bundesmarine, piloted by Kapitänleutnant Knut Anton Winkler, was shot at by MiG-21 fighters when it accidentally crossed into East German airspace near Eisenach.

Winkler, who had been returning from a training exercise on board U.S. Navy aircraft carrier USS Saratoga in the Atlantic Ocean, had to carry out an emergency landing at Ahlhorn, 45 km southwest of Bremen.