An Aeroflot airplane was forced to make an emergency landing after a pilot reportedly died mid-flight.

The 49-year-old first officer was flying from Moscow to Anapa when he fell ill during the flight. An attendant aboard the flight was looking for a doctor but could not find one in time.

“A stewardess practically ran across the aisle. They later asked if there were any doctors on board and said they really needed them. Then they asked again,” passenger Yelena Voronova told Russian news outlet RT.

“Unfortunately it was not possible to resuscitate the pilot,” an Aeroflot spokesperson told Daily Mirror.

The pilot complained about chest pains prior to boarding the flight but he passed a routine medical check-up and “had no health indicators that would have barred him from piloting the aircraft,” Aeroflot officials released in a statement.

The flight eventually continued to Anapa with a replacement co-pilot.

The cause of death is unclear but it is believed to have been a heart attack or blood clot. Aeroflot has launched an investigation to determine the cause of death.