When Uruguayan Air Force Flight 571 crashed in the Andes in October 1972, the surviving rugby players faced unimaginable odds. Among the wreckage lay a glimmer of hope: a working VHF radio set located in the severed tail section of the Fairchild FH-227D aircraft. Engineering student Roy Harley led a heroic effort to wire the radio up and broadcast their location to rescue teams.
However, the group was defeated not by broken circuits or damaged antennas, but by basic electrical physics. The aircraft's primary communication system was built to operate on 115-volt Alternating Current (AC), which was normally generated by the plane’s twin turboprop engines while in flight. After the crash, the only power source available was the plane's surviving 24-volt Direct Current (DC) batteries.
Without a functioning inverter—which had been destroyed during the impact—the survivors had no way to convert the 24V DC power to the 115V AC required by the high-frequency transmitter. Harley spent agonizing days in sub-zero temperatures splicing wires and attempting to bypass components, unaware that the fundamental current mismatch made transmitting impossible. They could receive commercial radio broadcasts using a smaller battery-powered transistor radio—where they tragically heard that search efforts were canceled—but sending an SOS broadcast required far more electrical power than scavenged DC batteries could ever deliver.
This devastating electrical catch-22 ultimately forced Nando Parrado and Roberto Canessa to undertake their legendary 10-day trek across the mountains to find help manually.