Investigation Summary
The accident was caused by a navigational error involving the misinterpretation of radio navigation instruments. Due to heavy cloud cover, the pilots relied on timed legs and radio beacons. After crossing the Planchón Pass, the co-pilot, Lieutenant-Colonel Dante Lagurara, who was being trained by Captain Ferradas, miscalculated the aircraft's position. He believed they had reached Curicó, Chile, when they were still approximately 60 to 69 kilometres to the east. He requested and received clearance from Santiago air traffic control to descend from 18,000 feet to 11,500 feet. As the aircraft descended into the clouds, it encountered severe turbulence and struck a ridge. The right wing clipped the mountain and was torn off, followed by the tail section, which contained the flight's navigator and steward. The left wing was subsequently lost after striking another rock outcropping. The remaining fuselage acted as a high-speed sledge, sliding 725 metres down the Glaciar de las Lágrimas (Glacier of Tears) before coming to a sudden halt in deep snow. The impact caused the cabin seats to break free and crush many passengers against the forward bulkhead. Three crew members and nine passengers died immediately, with several others dying shortly after due to injuries and the extreme cold. In total, 29 people died during the 72-day ordeal, including those lost in the initial crash, subsequent injuries, and a later avalanche.
Final Conclusions
The investigation concluded the cause was Controlled Flight Into Terrain (CFIT) resulting from pilot error. The crew failed to accurately track their position relative to the Curicó radiobeacon and initiated a descent while still over high terrain. The aircraft's performance limitations at high altitudes, combined with strong headwinds that slowed their ground speed more than anticipated, contributed to the miscalculation of their arrival time at the turning point.
Photographic Evidence (1)
Video Analysis
Andes Miracle - Why The Plane Crashed (A Deep Dive into Uruguayan Air Force 571) — A detailed technical breakdown of the navigational errors and flight conditions that led to the crash of Flight 571 in the Andes mountains.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Crew Experience
Captain
Colonel Julio César Ferradas
First Officer
Lieutenant-Colonel Dante Héctor Lagurara
Systems & Failure Modes
Radio Beacons (NDB/VOR)
The crew relied on the Malargüe and Curicó beacons to navigate the U-shaped route around the highest peaks. A premature turn was made based on an incorrect assumption of passing the Curicó beacon.
Fairchild FH-227D Performance
The aircraft had a service ceiling of 28,000 feet, but when fully loaded, its cruise altitude was limited to approximately 18,000–20,000 feet, necessitating the use of mountain passes rather than direct overflight of the highest peaks.
Interesting Facts
- 01The aircraft was a Fairchild FH-227D, a stretched, American-built version of the Fokker F27 Friendship.
- 02The flight was a charter for the Old Christians Club rugby team traveling from Montevideo to Santiago.
- 03The crash site was located at an altitude of roughly 3,500 metres (11,500 feet) in the Argentine Andes.
- 04Survivors resorted to anthropophagy (eating the flesh of the deceased) to stay alive during the 72-day ordeal.
- 05The final 16 survivors were rescued between December 22 and December 23, 1972.
- 06The aircraft came to rest 80km (50mi) to the east of its planned route due to the premature turn.
Safety Actions & Advisories
Pilot Training and Mountain Navigation
The investigation highlighted the dangers of relying on dead reckoning and timed legs in mountainous terrain without radar confirmation. It reinforced the necessity for pilots to verify their position using multiple radio navigation aids before initiating descents in Instrument Meteorological Conditions (IMC).
Air Traffic Control Coordination
The accident underscored the limitations of air traffic control in regions without radar coverage, where controllers must rely entirely on pilot-reported positions. This led to broader discussions on improving trans-Andean flight monitoring.