CHARLOTTE, N.C. (TheStreet) -- A day of East Coast thunderstorms in July could lead to massive delays in Charlotte, possibly stranding hundreds of connecting passengers in the airport overnight -- or even longer -- as they await seats on nearly full aircraft. Some might then decide that the US Airways division of American (AAL) is the worst airline in the world.

But that is not what we looked for in compiling a list of the five worst U.S. airlines of all time. Rather, we looked for airlines with flawed models, failed execution and, in some cases, severe operational deficiencies.

Despite occasional bad days, American and US Airways and other existing major airlines are not candidates for such a list. Their models obviously work and their execution is generally good, even if they remain hypersensitive to weather events and often, given high passenger loads that were unimaginable a decade ago, unable to quickly accommodate passengers whose flights are disrupted.

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To assemble the list of the worst ever, we consulted with about a half dozen people who are airline-obsessed. They included airline columnist Joe Brancatelli, airline consultant Bob Mann, Dallas Morning News airlines reporter Terry Maxon and others, some who are employed by airlines -- and who asked not to be named.

The bias was in favor of airlines that I personally covered. In fact, while they were operating, I interviewed top executives at all five. The executives all assured me that their airlines would succeed, even though in four of the cases airline experts were actively arguing that the chances for success were nil.

The exception was ValuJet, a success for a time, but one based on a flawed model where maintenance was outsourced and unable to accommodate the extremely rapid growth.

Importantly, as Mann said, in every case of a failed airline, "The saddest thing is you had employees who tried very hard to resolve what you knew and they knew to be problems. They were articulate about it and they communicated it, but for a variety of reasons management wasn't up to the task of listening or up to the task of fixing it.

"Either the strategy was bad or the management was bad or things just didn't work out," Mann said.

One of the executives, Air South Chairman John Tague, went on to become president of United (UAL), where he became known as a leader with a love for the industry and a willingness to communicate face-to-face with employees at all levels.

Maybe working at Air South helped make him that way.

Here is our list, which begins with Air South.

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