Indonesia's transport ministry said Saturday it would open a probe into local airline Batik Air after two of its pilots were found to have fallen asleep during a recent flight.

A pilot and co-pilot were simultaneously asleep for approximately 28 minutes during a flight from Southeast Sulawesi to the capital Jakarta on Jan. 25, a preliminary report by the National Transportation Safety Committee (KNKT) said.

The incident resulted in a series of navigation errors, but the Airbus A320's 153 passengers and four flight attendants were unharmed during the 2½ hour flight.