Batik Air, full-service carrier of Indonesia’s Lion Group, temporarily suspended two pilots after they fell asleep in the cockpit during a domestic flight in late January, the carrier said in a statement.

Flight 6723 was on its way to Jakarta from Kendari in Sulawesi on Jan. 25 with 153 passengers on board when neither the pilot or co-pilot responded to communications from the air traffic controller and another plane, according to the National Transportation Safety Commission. They were trying to contact the Airbus A320 after it failed to follow the designated route and headed past Jakarta toward the Indian Ocean.

Twenty-eight minutes after the last recorded transmission from the co-pilot, the captain woke up and became aware that the aircraft was not on the correct flight path. He then saw that his second-in-command, or SIC, was sleeping and woke him up, the NTSC wrote in the preliminary investigation report of what its described as a "serious incident.”