Rio Airways was a regional passenger airline headquartered in Killeen, Texas, United States, which was operational from 1967 to 1987. Rio Airways operated briefly in a code-share arrangement with Delta Air Lines whereby Rio flights were booked and sold under the "Delta Connection" brand name. Prior to the Delta Connection, Rio Airways (Code "XO") operated independently but shared terminal gates at the DFW airport first with Texas International Airlines (1974), then with Braniff (1975-1978). Prior to operations at DFW it operated at Dallas Love Field, having its roots in two smaller commuter air carriers, Dal Airways and Hood Airways.

In 1972, Rio pilots initiated collective bargaining efforts with proposed representation by the Teamsters, but vigorous opposition by Rio management and strong appeals by popular pilot Mike Mills, swayed the pilots to reject the union. Two years later, the Rio pilot group having grown dissatisfied with Rio management's failure to carry through with promises made to discourage the former unionization efforts, solicited the National Labor Relations Board (NLRB) to conduct another union vote. This time the initial solicitation was actually initiated by Mike Mills who personally handed out the solicitation cards to be signed by pilots, and the pilots unanimously voted ALPA subsidiary "UPA" as their collective bargaining agent.

After a year of failed negotiations the NLRB mediator declared a thirty-day "cooling-off" period and then made his recommendation known to the pilot group that "only a strike will likely force the company to abandon coercive and probably unsafe practices against the pilots." The pilots had an almost 100% walk-out beginning August 1976, with the exception of management pilot Herb Cunningham, and line pilots Mike Mills, Calvin Humphrey, Will Kilgore, and Hugh Longmoor remaining with the company. The company hired replacement pilots from across the country, many of whom arrived to discover the airline under a labor dispute.

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