On a spring evening in 1956, as 11 Sisters of the Villa St. Louis Convent in Orléans were getting ready for bed, a munitions-laden CF-100 military jet crashed through the walls of their living space and exploded.

Flames engulf building. (CBC)

It was the night of May 15, 1956. Neighbours rushed to help as jet fuel and munitions on the plane exploded. While 25 people made it to safety, 11 nuns, a priest, a servant, and both aircraft crew members died in the fire.

The tragedy at the rest home run by the Grey Nuns of the Cross is now known as one of the worst air disasters in Ottawa history.

The mystery

That evening, a transport plane had reached Ottawa earlier than planned. Radar images showed it as an unidentified plane. The Uplands Royal Canadian Air Force base dispatched a jet to identify and intercept the mystery aircraft.

A second jet was also dispatched. One of those jets landed safely. The other said it would continue flying to burn off some fuel. That was the last communication ever sent from the aircraft.

A body is carried away. (CBC)

The pilots gave no sign that they were in trouble. So how did the military aircraft end up where it did? Why didn't the pilot and navigator eject from their plane? Even 60 years later, those answers remain a mystery.

A firefighter at the scene. (CBC)

Orléans remembers

Sunday marks 60 years since the tragedy. A group of 40 ex-airmen from the Ottawa area called the 410 Wing of the Royal Canadian Air Force Association will be remembering those who died in the fire.