Low-cost Dutch airline Transavia has opened a probe after one of its pilots was locked out of the cockpit mid-flight after his co-pilot fell asleep, Dutch authorities said Wednesday.
The incident, which occurred on a Boeing 737 flight to Crete in Greece in September, was made public by the Dutch safety board (OVV) in a quarterly report published on its website. The body called it a "serious" incident.
"After two and a half hours in the air the captain of the Dutch-registered plane left the cockpit to go to the toilet," the OVV said.
"A little later he wanted to return to the cockpit. When he used the intercom to call the first officer to open the door he got no reaction.
"When he managed to get into the cockpit, he found the first officer asleep," the OVV said, adding that Transavia was investigating the incident.
The OVV said it would decide what action to take after receiving Transavia's report.
Transavia is a subsidiary of Air France-KLM.