Mexicana de Aviación Flight 940, operated by Mexicana de Aviación, was a scheduled international flight from Mexico City to Los Angeles with stopovers in Puerto Vallarta and Mazatlán on March 31, 1986, utilizing a Boeing 727-200 registered as XA-MEM, when the plane crashed into El Carbón, a mountain in the Sierra Madre Occidental mountain range northwest of Mexico City, killing everyone on board. With 167 deaths, the crash of Flight 940 is the deadliest aviation disaster ever to occur on Mexican soil, and the deadliest involving a Boeing 727.

Compañía Mexicana de Aviación, S.A. de C.V. was Mexico's oldest airline and one of the oldest continuously single-branded airlines, inaugurated in 1921. It was Mexico's biggest airline and flagship airline before ceasing operations on August 28, 2010, leaving competitor Aeromexico as a de facto monopoly.