Era Alaska says it has completed all necessary upgrades and the Era Aviation fleet is resuming scheduled operations in Alaska after the commuter airline grounded 12 planes last weekend.

In a statement Tuesday evening, President and CEO Bob Hajdukovich said staffers completed the upgrades quickly and thoroughly. He thanked customers for their patience.

The airline resumed some limited service on Monday.

The planes were grounded after Federal Aviation Administration officers determined cockpit voice recorders were out of date. Era says high winds also affected some flights.

KMXT reported that the federal investigation stems from an incident this month when an Era plane traveling from Anchorage to Homer dropped 5,000 feet before pilots regained control.