Crash site of SR 306 near Dürrenäsch
|Date||September 4, 1963|
|Summary||In-flight fire leading to hydraulic failure and loss of control|
|Aircraft type||Sud Aviation SE-210 Caravelle III|
|Flight origin||Zurich Airport|
|Stopover||Geneva International Airport|
Swissair Flight SR306, a Sud Aviation SE-210 Caravelle III, named Schaffhausen, was a scheduled international flight from Zürich to Rome, via Geneva. It crashed near Dürrenäsch, Aargau, on September 4, 1963, shortly after take-off, killing all 80 people on board.
Zurich Airport was in dense fog when the plane was due to take off at 06:00 UTC. At 06:04 the flight was allowed to taxi to runway 34 behind an escorting vehicle. At 06:05 the crew reported that they would taxi halfway down runway 34 to inspect the fog and then return to the take off point. This was done using high engine power in order to disperse the fog. Around 06:12 the aircraft returned to runway 34 and was allowed to take off, which it did 06:13, and started to climb to flight level 150, its cruising height.
Four minutes later people on the ground noticed a white trail of smoke coming from the left side of the aircraft. Shortly after, a long flame erupted from the left wing. Around 06:20 the aircraft reached a height of about 2700 m. It then began to descend, entering a gentle left turn before losing height more quickly. It then went into a final, steep dive.
The aircraft's brakes overheated due to the application of full engine power during taxiing. This caused the magnesium wheels to burst, one of them on the runway prior to departure. Upon retraction of the landing gear, the hydraulic lines in the gear bay were damaged. This was caused either by the wheels that had exploded, or the bursting of the other wheel rims during the climb. Subsequently, spilled hydraulic fluid ignited when it came in contact with the overheated landing gear rims. The fire damaged the gear bay, followed by the wing. Finally losing its hydraulic pressure, the aircraft became impossible to control. The cabin and the cockpit were filled with smoke, adding to the predicament of the crew. Control of the aircraft was lost totally at around 06:18, and the ensuing final dive and impact destroyed the aircraft.
As a result of this accident, all Caravelles were modified to use non-flammable hydraulic fluids.
This crash severely affected the small village of Humlikon in the Canton of Zürich: 43 of its 217 citizens (20% of the population) boarded the plane to visit a farm test site near Geneva. Among those who perished were the entire local council, all members of the local school board, and the village's post office clerk. A number of children who were orphaned were looked after at home by relatives, and six of these children had to move, all but one of whom went to live with relatives nearby. There were 74 Swiss nationals on board as well as two Americans (one dual citizenship with Iran), one Briton, one Egyptian, one Israeli, and one passenger either from Belgium or Austria.
Further problems arose with the upkeep of the local farms, but people from the nearby villages helped. Apprentices came from local firms, students, firemen, soldiers, boy scouts, railroad workers and policemen, as well as volunteer school children, and even from abroad to help. 600 tons of potatoes were harvested manually, corn was threshed and the new crop seeds were sown in time. Just over a month after the crash, a new council was elected by the 52 remaining eligible voters.