Passenger rights advocates on Tuesday staged an unofficial hearing on Capitol Hill to discuss their grievances regarding extended tarmac delays, and their desire to pass legislation that would require airlines to give passengers the option to disembark after three hours. Former American Airlines CEO Robert Crandall supports proposed legislation being sponsored by Sen. Barbara Boxer, D-Calif. However, Crandall noted that there could be unintended consequences to a 3-hour limit. "It is clear that the full ramifications of any policy need be fully and carefully considered," said Crandall. Another participant, University of Michigan associate professor Amy Cohn, warned that one potential impact of imposing a time limit would be an increase in flight cancellations. "I think some passengers may be helped, and others may be harmed," she said. Cohn also said the focus on extreme delays is diverting attention from the more pressing problem -- that of routine system delays.