Phoenix - Southwest Airlines has been hit with a big fine for the way it bumps customers from oversold flights.

The Transportation Department announced it was fining Southwest $200,000 after reviewing customer complaints.

It said Southwest failed to pay passengers in a timely manner and did not give passengers written notices of their rights on how the airline decides who to bump.

When a flight is overbooked, airlines must first ask for volunteers to give up their seats in exchange for financial compensation followed by bumping passengers who bought tickets.