1926    Varney Airlines makes its first commercial flight (Varney is the root company of United Airlines).

1931    United Airlines begins service (as Boeing Air Transport).

1933    United Airlines Chesterton Crash: A United Airlines Boeing 247 is destroyed by sabotage, the first such proven case in the history of commercial aviation.

1956    A TWA Super Constellation and a United Airlines DC-7 (Flight 718) collide above the Grand Canyon in Arizona, United States, killing all 128 on board the two planes.

1960    1960 New York air disaster: While approaching New York's Idlewild Airport, a United Airlines Douglas DC-8 collides with a TWA Lockheed Super Constellation in a blinding snowstorm over Staten Island, killing 134.

1972    United Airlines Flight 553 crashes after aborting its landing attempt at Chicago Midway International Airport, killing 45.

1995    The long range Boeing 777 enters service with United Airlines.