Southwest Airlines plans to stop overbooking flights — an industry practice implicated in an ugly incident on a United Airlines flight that has damaged United’s reputation with the flying public. Beth Harbin, a Southwest spokeswoman, said Thursday that with better forecasting tools and a new reservations system coming online next month the airline will no longer have a need to overbook flights. Some critics have said airlines should leave a few seats empty if they think they will be needed by crew members. Chief Financial Officer Tammy Romo said doing away with overbooking would reduce costs — airlines compensate passengers for giving up their seats — which would offset some of the revenue hit.