An inquiry has been launched after the Indian Directorate General of Civil Aviation (DGCA) found out that a Jet Airways flight abruptly descended 5,000 feet over Turkish airspace, on August 8.

The Indian media reports that the incident first came to light on August 12 when the Director General of DGCA, Lalit Gupta, received an anonymous SMS, informing him about the incident.

It was discovered that the captain of the flight 9W-228, on its way from Mumbai to Brussels, was taking a controlled nap at the time while his co-pilot was supposed to sit on the controls. However, the co-pilot claimed that she did not notice that the aircraft is descending below the assigned level since she was busy with her electronic flight bag (EFB) – a tablet containing aircraft documents. She realized the situation only after getting a call from the air traffic controller in Ankara, Turkey, and immediately woke up the captain, who then brought the Boeing 777-300 back to its level.

The DGCA has suspended the pilots and launched an investigation to find out whether the sudden drop was caused intentionally or accidentally by the co-pilot. The DGCA has also decided to audit the airline’s training procedures for the pilot.

According to Jet Airways, “The airline is also extending all co-operation in the matter to the DGCA by providing all necessary assistance for the inquiry. Safety is of paramount importance to Jet Airways as is also the welfare of our guests and crew and the airline will always take appropriate steps to ensure the same.”