CHICAGO (CBS13) — New documents obtained by CBS News show the situation at Southwest Airlines is worse than previously known. At different times throughout the last week, more than 60 Southwest 737s were taken out of service by mechanics for unscheduled maintenance. The airline says the “unscheduled aircraft downtime,” or UADs, have spiked at several maintenance hubs in particular.

Southwest said that since February 12, the average UAD in Orlando has surged to 60 hours a day compared to an average of 10.2 hours per day over the last two years. In Houston, the UAD had averaged 18.6 hours a day but jumped to 111 hours on February 12, then rose again to 127 the following day.

Read more: More Southwest planes out of commission as airline battles with mechanics