The latest annual fleet airworthiness review, obtained by The Canadian Press under the access-to-information law, paints a compelling portrait of how military aviation is being changed by drones.
Experts also say it underlines the need for countries and the international community to create target levels of safety for the remotely operated vehicles.
"The overall (Canadian Forces) air accident rate less Cadets and UAVs has increased compared to 2009 and remains higher than the 10-year mean," said a July 7, 2011, briefing note for Defence Minister Peter MacKay.
Between 2007 and 2010, there were 10 crashes of unmanned aerial vehicles, according to the airworthiness survey, dated June 10, 2011. Most the accidents involved engine failures and the majority of them happened in Kandahar during the war.
Since the Canadian military started using drones in the early 2000s, there have been 42 accidents.
Unlike crashes of manned planes, the air force has rarely acknowledged in public when one of their drones is lost. Unmanned aircraft do not make up the majority of accidents, but their increasing use has underlined an inevitability.
"There are going be to crashes it's a given," said Keven Gambold of the firm Unmanned Experts, a former fighter-bomber pilot and UAV operator with the Royal Air Force.
Throughout the latter half of the Afghan war, Canadian operators flew CU-170 Herons, leased from MacDonald, Dettwiler and Associates Ltd. and used them for battlefield surveillance.
The Israeli-made Herons replaced CU-161 Sperwers, a catapult-launched vehicle the military adopted in the early 2000s, which were responsible for the majority of the accidents.
The Canadian military has signalled that, in addition to overseas missions, it will begin using UAVs over Canadian soil and plans to conduct further flight tests this summer over the Arctic.
It was revealed this week the Harper government is considering a proposal to buy at least three high-altitude Global Hawk unmanned aerial vehicles from U.S. defence contractor Northrop Grumman for possible use in the Far North.
Capt. Claire Maxwell, an accident investigator with the military flight safety, said drone crashes are a rare occurrence and the air force has learned lessons from each one.
"We're much better educated on how to receive UAVs and we're prepared to implement a program," she said.
Maxwell said the air force rigorously monitors safety once a UAV is under their control, but the concern of observers is the testing that goes on before it reaches the flight line.
The aviation community and government regulators around the world, including Transport Canada, are grappling with the establishment of a target level of safety for drones.
Once the exclusive purview of the military, now police agencies and even private corporations are clamouring to put their own UAVs in the sky in a potentially air-choking melee.
The aim, currently, is to set the safety standard for drones below that of commercial airliners, but above small private aircraft, such as the Cessna. Jetliners have among the most rigorous guidelines.
The plan is to make it "safer than the general aviation community, but it's less safe than the air carrier," said Gambold.
Since the standards haven't been carved in stone by the international community and many countries, the manufacturers of the remote-controlled aircraft have not been required to put in back-up systems, such as duel flight controls, in case of failure.
Gambold said there has been some concern about the reliability and security of the data links, which allow the operator to fly the plane remotely. The industry has begun addressing that on its own, but like other aspects it is not regulated.
"It hasn't been mandated," he said. "That's the problem. When these things are built and certified, they have to reach that standard."
There is also a debate going within the UAV community about whether operators should be fully trained pilots, whose hand-eye co-ordination is paramount, or whether to use specially trained operators, whose ability to manipulate the keyboard and understand spatial awareness is key.
But the training for operators is a patchwork, depending on the country.
"These definitions are not robust because there is no such thing as a commercial pilot's licence for an unmanned aerial vehicle," said Gambold.