Background
The aircraft involved was a Bristol 170 Mk 21, manufactured in the United Kingdom in 1946, with serial number 12757 and registration EC-ADI. It was operated by Aviaco. The flight crew consisted of a captain, first officer, flight engineer, and two flight attendants. The captain held a commercial pilot's license issued on 16 January 1952 and had accumulated 5,478 flight hours. The first officer had 427 flight hours.
Accident
On 9 May 1957, at 19:04 CET, Aviaco Flight 111, a domestic scheduled flight from Santiago de Compostela to Madrid, crashed near Madrid–Barajas Airport during approach to land on runway 23. While on the downwind leg, the aircraft was banked slightly to the left to allow the captain to see the control tower's green landing clearance signal. After spotting the signal, the captain initiated a right bank. During this maneuver, the aircraft entered an unrecoverable right-hand spin, lost control, and struck the ground, catching fire. All 37 passengers and 5 crew members died. The airport fire department reached the crash site within six minutes but took about one hour to extinguish the fire. The fire was contained sufficiently that occupants could have been rescued had the impact not been fatal.
Investigation
The investigation determined that the accident was caused by pilot error. A failure in radio communication forced the captain to rely on visual signals from the control tower for landing clearance. This distraction led to a loss of situational awareness, and the aircraft crashed before reaching the runway.