1970-AUG-09 · San Jerónimo, near Cusco, Peru

Líneas Aéreas Nacionales S.A. (LANSA) — Flight 502

LANSA Flight 502 crashed shortly after takeoff from Cusco after the number 3 engine failed during the climb. The flight was carrying a large group of American exchange students. Following the engine failure, the crew failed to follow proper engine-out procedures, retracting flaps prematurely and entering a steep bank that led to a loss of control. The aircraft struck a hill in the San Jerónimo district, killing 99 of the 100 people on board and two people on the ground. The investigation cited poor maintenance and improper loading as contributing factors.

Aircraft

Lockheed L-188A Electra

Registration

OB-R-939

Phase

Initial climb

Cause

Pilot Error

Souls on Board

100

Fatalities

Origin → Dest

Alejandro Velasco Astete International Airport, Cusco, Peru → Jorge Chávez International Airport, Lima, Peru

Report

Destroyed

Investigation Summary

The aircraft, a Lockheed L-188A Electra named 'Tupac Amaru', was heavily loaded for its departure from the high-altitude Cusco airport (10,860 ft MSL). During the takeoff roll, which was noted to be 700 meters longer than normal, the number three engine failed. Despite the failure, the crew continued the takeoff and reached an altitude of approximately 300 feet. At this critical juncture, the crew retracted the flaps while maintaining a speed of 140 knots. This caused the aircraft to lose lift and enter a steep left bank of 30 to 45 degrees. The aircraft was unable to maintain altitude in the thin mountain air with one engine out and the flaps retracted, leading to a collision with terrain approximately 4.5 kilometers east-southeast of the airport in the San Jeronimo district.

Final Conclusions

The Peruvian government concluded the primary cause was the flight crew's improper execution of engine-out procedures, specifically the premature retraction of flaps and the subsequent loss of control during a steep turn. Contributing factors included improper maintenance by LANSA personnel, which led to the initial engine failure, and improper loading of the aircraft, which exacerbated the performance issues at high altitude.

Photographic Evidence (1)

Video Analysis

No video analysis linked for this case file yet.

Systems & Failure Modes

Number 3 Engine

The Allison 501-D13 turboprop engine failed during takeoff due to inadequate maintenance.

Flaps

Retracted prematurely at 300 feet, reducing the lift required to maintain flight on three engines at high altitude.

Interesting Facts

01The crash killed 49 American high school exchange students from the International Fellowship program.
02The co-pilot was the sole survivor among the 100 people on board.
03Two farmers on the ground were killed by the impact.
04The aircraft was named 'Tupac Amaru' and was manufactured in 1959.
05The accident was the deadliest in Peruvian history at the time.