He then pulled his Bf 109 into a steep climb, while turning the aircraft, extending the undercarriage, and sideslipping the excess altitude before touching down. He had executed this risky maneuver many times before but apparently had misjudged his height and at the edge of the airfield. Tonne was posthumously promoted to Major (major).
On 20 April 1943, Tonne claimed his 122nd aerial victory. Returning from that mission, he was killed in a flying accident over the airfield at Protville in his Bf 109 G-6 /R1 (Werknummer 16523). Tonne had waggled his wings to single an aerial victory claimed.