But the only available seats to get home for Christmas were on LANSA. The flight left Lima’s Jorge Chávez International Airport on the morning of December 24, bound for Pucallpa with a connection that would eventually get them to Panguana. Ninety-two people were on board: eighty-six passengers and six crew. The aircraft was a Lockheed L-188A Electra, a turboprop that had been introduced in the late 1950s and was a standard workhorse of regional aviation in South America. Its registration was OB-R-941.
The holiday season created specific pressures. The flight was carrying people home for Christmas. The schedule mattered to passengers and, apparently, to the crew as well. Peruvian investigators would later conclude that the flight crew chose to continue into hazardous weather rather than divert or hold, under conditions where a more conservative decision might have been prudent. The language of the investigation findings — “intentional flight into hazardous weather conditions” — describes a judgment call made in conditions that made the call difficult to make well.
## The Storm and the Breakup
The Peruvian Amazon in late December sits in its wet season. Thunderstorms build rapidly and can reach intensities that make them genuinely dangerous to aircraft, not merely uncomfortable. The afternoon thunderstorm culture of the Amazon basin is well understood in modern aviation meteorology; in 1971, understanding it and having the tools and protocols to respond to it reliably were not as advanced.
About fifteen minutes before the planned landing at Pucallpa, at a cruising altitude of approximately 6,400 meters (FL210), the aircraft entered a severe thunderstorm. The turbulence and updrafts and downdrafts inside a mature Amazonian thunderstorm are extreme — not comparable to the ordinary turbulence of cruise flight in disturbed air, but the violent, aircraft-testing kind that can impose structural loads well beyond what commercial aircraft are designed to withstand.