Invicta International Airlines Flight 435

Invicta International Airlines Flight 435 (IM435) was a Vickers Vanguard 952, flying from Bristol Lulsgate to Basel-Mulhouse, which crashed into a forested hillside near Hochwald, Switzerland on 10 April 1973. The aircraft somersaulted and broke up, killing 108 people, with 37 survivors. To date, this is the deadliest accident involving a Vickers Vanguard and the deadliest aviation accident to occur on Swiss soil. Many of the 139 passengers on the charter flight were women, members of the Axbridge Ladies Guild, from the Somerset towns and villages of Axbridge, Cheddar, Winscombe and Congresbury. The accident left 55 children motherless and became known in the British media as the Basle air crash.

Pilot Anthony Dorman became disoriented, misidentifying two radio beacons and missing another. When co-pilot Ivor Terry took over, his final approach was based on the wrong beacon and the aircraft crashed into the hillside. Dorman had previously been suspended from the Royal Canadian Air Force for lack of ability, and had failed his United Kingdom instrument flight rating test eight times. As a result of the crash, tougher regulations were introduced in the UK.

Despite the conclusions of the official Swiss report, one commentator, ex-KLM pilot Jan Bartelski, has argued that the pilots may not have been entirely to blame and that there is a possibility that they were led off course by "ghost" beacon transmissions caused by electric power lines.