MANILA, Philippines (CNN) -- Beleaguered Philippine Airlines is back in the air, after being closed for 13 days. The national flag carrier resumed operations Wednesday morning.

Debt-ridden PAL had shut down at midnight September 24 after the airline's largest union rejected a management offer to give employees 20 percent equity in exchange for a 10-year freeze on labor bargaining.

Last week, however, employees approved the offer overwhelmingly in a second referendum, allowing the 57-year-old airline -- Asia's oldest -- to resume flights.

Its fleet of 54 aircraft had flown to 36 domestic destinations and 28 world cities. On Wednesday, the airline was flying domestic routes only to 13 airports.

The total passenger load was only 30 to 60 percent Wednesday, well below the average 65 to 70 percent, but airline officials expected its bookings to normalize within two weeks. The late-September closure of PAL had left many areas of the 7,000-island archipelago without air service, severely impacting tourism.

Reuters Limited contributed to this report.