The Air Algerie crash that killed 116 people in the Mali desert in 2014 was caused by the pilots failing to activate the plane's anti-icing system and not responding properly when the plane stalled, investigators said Friday.
The McDonnell Douglas MD-83 crashed in northern Mali in bad weather, barely half an hour into its flight from Burkina Faso's capital Ouagadougou to Algiers, killing everyone on board.
France bore the brunt of the tragedy with 54 dead -- nearly half of the victims -- and in some cases, whole families wiped out.
Presenting the final report by investigators from France's BEA civil aviation authority in Bamako on Friday, Mali's Transport Minister Mamadou Hachim Koumare said engine pressure sensors had become blocked, seemingly by ice crystals, and the crew did not turn on the anti-icing system.
BEA director Remy Jouty, speaking at the agency's headquarters in Le Bourget, near Paris, said the blocked sensors had caused the engines to lose power and the plane to lose speed.
"It appears the crew did not notice or did not respond to this loss of speed until the plane stalled," Jouty said.
Investigators were unable to access the cockpit voice recordings, Jouty said, making it difficult to assess what was happening on the flight deck when the pilots seemingly failed to take action over the falling speed and stall alarms.
When these alarms sounded, "the situation was in theory recoverable", he said.
The report called for a permanent engine anti-icing system to be studied for the McDonnell Douglas plane, along with modifying the criteria for the system to be activated and further stall training for crews.
In April last year the BEA -- which was invited to help with the probe by Malian authorities -- said data showed that as they got into difficulties, the pilots did not attempt a manoeuvre to pull the plane out of a stall.
A French judicial probe last year, reported by Le Figaro newspaper, also pointed to other factors behind the crash, including the pilots' lack of experience flying in African weather.
The head of a group representing French victims of the crash, Delphine Tricot, said "a succession of errors, blunders and incompetences" had caused the crash, claiming the pilots were too tired.
But Jouty said the crew was experienced and familiar with both the route and likely weather conditions.
He also said that in the days before the crash, the pilots' flying workload was normal and planning for the flight conformed to European regulations.
The crash in July 2014 was the third fatal incident worldwide in the space of just eight days, capping a disastrous spell for the aviation industry.
It followed the shooting down of a Malaysia Airlines plane in restive eastern Ukraine, killing all 298 people on board, and the crash of a flight in torrential rain in Taiwan, with the loss of 48 lives.