Travellers wait in line to check-in at a Southwest Airlines counter at Los Angeles International Airport on July 21, 2016 in Los Angeles, California. A Southwest Airlines computer failure has grounded flights nationwide since July 20 leaving passengers stranded or waiting for long delays as some 700 Southwest flights were cancelled nationally with more than 300 flights canceled by 8am today, according to the airline, with the number rising to about 450 by mid-afternoon. / AFP PHOTO / Frederic J. BROWNFREDERIC J. BROWN/AFP/Getty Images
