Background
On November 21, 1977, three aircraft were chartered to transport 31 newlywed couples to Bariloche, Argentina, for their honeymoon. The accident aircraft was the second of the three to depart.
Accident
While climbing to 35,000 feet (11,000 m), the aircraft experienced pressurization problems and was forced to descend to 29,000 feet (8,800 m). At 00:40, the flight was cleared for an Instrument Landing System (ILS) approach to runway 28, but the crew abandoned the approach due to a VOR receiver problem. The pilot then requested a visual approach to runway 10, but subsequently decided to perform another ILS approach to runway 28 using a different ILS procedure. The pilot reported that the aircraft was near the VOR beacon; this was the last transmission from Flight 9. The aircraft then crashed into a mountain. All five crew members and 41 passengers died, bringing the total fatalities to 46 out of 79 occupants.
Investigation
Investigators determined that the flight crew descended prematurely and did not follow the allowed ILS procedure, possibly due to VOR signal malfunctions and the captain's mental state.