There is a very slim chance that investigators will ever find the black boxes from an Air France jet that crashed into the Atlantic Ocean on Monday.

A French official made the comment on Wednesday. He said the rough terrain at the bottom of the waters would make the search difficult.

The boxes contain important flight data that could shed light on the disaster.

There were 228 people on board the Airbus A330 that disappeared en route to Paris from Rio de Janeiro.

One of them was Canadian Brad Clemes, 49. He left behind a wife and two adult sons.

Brazilian military pilots conducting a search spotted an airplane seat, a life jacket, metallic debris and signs of fuel in the middle of the Atlantic Ocean on Tuesday, but found no signs of life.

Among the plane’s 216 passengers were 61 French citizens, 58 Brazilians, 26 Germans, nine Chinese and nine Italians. A lesser number of citizens from 27 other countries were also on the passenger list, including two Americans.

Among the devastating losses were ten salesmen for France-based CGED, an electrical distributor, who were on the plane with their spouses after winning a vacation to Brazil.

Air France said 11 of the 12 crew members were French. The flight captain, 58, joined the company in 1988 and had 11,000 flight hours, including 1,700 on aircraft of the same type as the passenger jet that disappeared. The two co-pilots were 37 and 32 and had over 9,000 flight hours between them.

With files from Tamsyn Burgmann, The Canadian Press

Photo credit Evaristo Sa/AFP/Getty Images.