Boarding a plane has become one of the most painful parts of modern travel, taking upwards of half an hour and triggering panic — and the possibility of violent squabbles — about available space in overhead lockers. This week, United implemented its new WILMA boarding system in a bid to expedite the agonizing experience, but the method has already sparked furious backlash amongst customers, some of whom are threatening a boycott of the airline. However, Southwest and American Airlines have also come under fire for their boarding policies.