Both the pilots have been summoned by the Directorate General of Civil Aviation over the incident.
It is reported that at the time of the incident, the commander of the flight was taking a 'controlled rest', which means a nap as per rules. The investigators are now probing whether the co-pilot had dozed off too.
However, the co-pilot claimed that she was busy on her tablet and did not notice that the aircraft had lost altitude. An alarm call from the Ankara ATC is what jolted th epilots to action.
Jet is also conducting a separate enquiry, while the pilots and the co-pilots have been suspended pending inquiry.