The US Department of Transportation says it will look into the mass flight cancellations by Southwest Airlines over the holiday weekend.
The cancellations left thousands of travelers stranded at airports across the country amid a major winter storm that has killed dozens of people.
Many airlines were forced to cancel flights, but Southwest was by far the worst of the bunch.
Of the almost 4,000 flights that were canceled Monday, 2,900 were by Southwest.
Other major airlines, including American, United, Delta and JetBlue, suffered cancellations rates of between zero and 2%.
The cancellation rate at Southwest Airlines? 62%.