Indonesia is investigating local airline Batik Air after both pilots were found to have fallen asleep during the flight for 28 minutes.
Both men, who have been temporarily suspended, fell asleep on a flight from Sulawesi to the capital Jakarta on January 25.
One of her girlfriends was reportedly tired from helping care for newborn twins.
The Airbus A320 briefly veered off course but landed safely and all 153 passengers and crew were uninjured.
A 32-year-old pilot told his co-pilot about 30 minutes after takeoff to take control of the plane because he needed to rest.
The 28-year-old co-pilot also agreed, according to a Department of Transportation report.
However, the co-pilot also accidentally fell asleep. He was helping his wife take care of their one-month-old twin babies, the report said.
Jakarta Air Traffic Control attempted to contact the Batik Air A320 cockpit after the last recorded transmission but received no response.
This radio silence lasted for 28 minutes until the main pilot woke up and realized that the co-pilot was also asleep. He also noted that the plane briefly veered off course.
The pilot then responded to a call from Jakarta and safely landed the aircraft.
A pre-flight medical examination determined that the men were fit to fly.
Her blood pressure and heart rate were normal, and an alcohol test was negative.
But while the pilots appeared to be fully rested, the test could not determine whether the quality of their rest was good, aviation expert Alvin Lee said.
Authorities have “strongly reprimanded” Batik Air for the incident, with Indonesian air transport chief M. Christi Enda Murni saying Batik Air should pay more attention to crew rest periods. said.
Batik Air says it “operates with appropriate rest periods” and is “committed to implementing all safety recommendations.”
In 2019, a pilot on the same airline passed out and was forced to make an emergency landing.
Aviation regulations in most countries require the presence of at least two pilots in the cockpit of a commercial aircraft.