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That explains why last week Mogel had a big gray tent pitched in his backyard in Collegeville, Pennsylvania, a Philadelphia suburb.

The tent, owned by Hanni’s Coalition for an Airline Passengers’ Bill of Rights, will be set up on the Mall in Washington on Wednesday for a “Strand-In.” The idea is to demonstrate conditions in the cramped cabin of a grounded airplane.

“The tent is 28 feet long, 12 feet wide, and 10 feet high. We had it shipped to Mark because he’s so great at logistics,” says Hanni.

Until the end of last year, Hanni, 47, was a real estate agent in California specializing in relocations. But that thriving business (Hanni says she sold $40 million in property in 2005) went on indefinite hold on December 29, the day she and other passengers were stuck on a tarmac in Austin for more than nine hours. Hers was one of dozens of American Airlines planes stranded at various airports after bad weather diverted flights from Dallas.

Infuriated by the conditions on the plane and by what she regarded as airline indifference to affected passengers, Hanni quit her job and began a protest movement. Since January, her group has been pressing Congress for federal legislation that would require airlines to let passengers off stranded planes after three hours and to provide adequate food, water, and sanitation while passengers remain on board.

Hanni and her husband, Tim, a well-known wine expert, took out a $200,000 line of credit on their Napa home earlier this year so Kate could plunge into the effort with what friends say is characteristic single-mindedness. She inspires such single-mindedness too; Mogel was one of hundreds of volunteers who casually signed up and soon found themselves putting in long days for Hanni. “I emailed them and said they needed to get better organized,” says Mogel, 51, who found the group online, after having been stranded on a plane for more than five hours. “Six months later, I’m still telling her, ‘You know, Kate, I can’t do this full-time.’ But she always has a new assignment.”

Traveling on her own dime or donations, Hanni has been to Washington more than 20 times since starting the group. Using Windsor Park, an inexpensive hotel in the Kalorama neighborhood, as a base, she roams the halls of Congress, toting bulging files and buttonholing the members of the transportation and aviation committees and subcommittees in each house—and their staffs . As a result, legislation providing for a Passengers’ Bill of Rights is now pending in both houses.

The group’s success (it now has 17,000 members) has been helped by fury over the extraordinary number of planes stranded this year at domestic airports, as unprecedented travel demand smacked headfirst into reduced airline capacity, record delays and cancellations, and schedules that no longer have slack built in to accommodate even routine weather disruptions.