Indonesia's Batik Air is to be investigated after two pilots fell asleep during a flight

(CNN) — Indonesia's transport ministry will launch an investigation into local airline Batik Air after two of its pilots fell asleep during a recent flight, state news agency Antara reported, the director general of the ministry's civil aviation department, M. Quoting Christie Enda Murney.

According to a preliminary report released by the National Transportation Safety Board (KNKT) this Saturday, the pilot and co-pilot of the flight from Kentari in Southeast Sulawesi to the capital Jakarta on January 25 slept for 28 minutes simultaneously. Navigation errors occurred because “the aircraft was not on the correct flight path”.

No one on board, including 153 passengers and four flight attendants, was injured during the flight and there was no damage to the plane, KNKT said in a preliminary report.

Flight BTK6723 lasted two hours and 35 minutes and landed successfully in Jakarta, according to Antara and the initial report.

CNN contacted Batik Air.

According to the KNKT report, the second-in-command pilot announced earlier that his co-pilot was not getting “enough rest.”

On the flight before the incident, the second-in-command pilot managed to sleep for “about 30 minutes”. After the aircraft took off from Kendari and reached cruising altitude, the pilot-in-chief requested permission to rest and the second-in-command pilot took charge of the aircraft. About 90 minutes after takeoff, the second-in-command's pilot “involuntarily fell asleep,” the report said.

About 12 minutes after the last transmission by the co-pilot, the Jakarta Area Control Center (ACC) tried to contact the plane, but received no response from the pilots, the report said. About 28 minutes after the last recorded transmission, the pilot-in-chief awoke and realized the plane was not on the correct flight path, at which time he woke up the second-in-command pilot and responded to ACC, the report said.

The initial report described the chief pilot informing ACC that the aircraft had experienced a “radio communication problem”, which was resolved.

The statement did not name the pilots, but identified the pilot-in-chief as a 32-year-old Indonesian man and the second-in-command as a 28-year-old Indonesian man. The second-in-command pilot had 1-month-old twins and “had to get up several times to help his wife care for the children,” the report said.

“We will investigate and review the operation of night flights in Indonesia regarding fatigue risk management for Batik Air and other airline operators,” Murni said in a statement.

The flight crew of BTK6723 has also been suspended as per standard operating procedure, pending an investigation, the news agency said.

He also said the company would send an approved Safety Problem Resolution (RSI) flight inspector to investigate the cause of the incident and recommend mitigation measures to the flight operators and supervisors, Antara reported.