24 fatalities

1977-12-29: Vickers Viscount (HC-BEM) — SAN Ecuador - Servicios Aéreos Nacionales — Cuenca-Mariscal La Mar, Ecuador

Cuenca-Mariscal La Mar, EcuadorLanding (descent or approach)

On December 29, 1977, a Vickers Viscount (registration HC-BEM) operated by SAN Ecuador - Servicios Aéreos Nacionales was involved in an aviation accident near Cuenca-Mariscal La Mar, Ecuador during landing or approach. 24 people were killed. Investigators recorded the probable cause as: Following several negligences, the crew started the descent prematurely under VFR mode in clouds, causing the aircraft to continue below the minimum prescribed altitude until it struck the mountain (controlled flight into terrain). This summary draws on records from the Bureau of Aircraft Accidents Archives (B3A); 3 related events involving the same aircraft type or operator are linked below.

Sourcesthe Bureau of Aircraft Accidents Archives (B3A)Primary reportUpdated 1781227201Data APIEditorial standards

A four-engine aircraft struck a mountain near Cuenca while descending under VFR in low clouds. The aircraft was destroyed and all 24 occupants were killed.

Accident

The crew filed an IFR flight plan from Guayaquil to Cuenca. After passing over the city of Puna, the pilot canceled the flight plan and continued under VFR. While descending to Cuenca, the crew encountered low clouds and failed to realize the aircraft's altitude was insufficient. The four-engine airplane struck the slope of a mountain a few kilometers from the airport. The aircraft was destroyed upon impact, and all 24 occupants were killed.

Probable Cause

The official investigation determined that, following several negligences, the crew started the descent prematurely under VFR mode in clouds, causing the aircraft to continue below the minimum prescribed altitude until it struck the mountain, consistent with controlled flight into terrain.