A U.S. security decision that banned private Canadian aircraft from flying through American airspace when travelling between cities in Canada affected dozens of flights and cost thousands of dollars in extra fuel before the decision was reversed, industry officials say.

The U.S. Federal Aviation Administration [FAA] issued a notice Dec.14 last year warning private pilots that all foreign private planes now had to obtain diplomatic clearance from the secretary of state before entering U.S. airspace.

The situation persisted for a month and cost thousands of dollars in increased fuel as planes had to be diverted.

Bernard Gervais president of the Canadian Owners and Pilots Association [COPA] worries the situation could reoccur.

"I don't want this to happen again," Gervais told CBC News. "It's a big issue for us. We need overfly there. There's no wall between our countries. It's always been that way."

Rudy Toering, president of the Canadian Business Aviation Association, says he wants reassurance from Transport Canada and the FAA that both agencies will follow the proper protocol in the future.

We want to know "that there will be direct communications between Canada and the United States as far as what are the impacts of this particular [decision]," Toering said.

"We're taking steps both from COPA and from ourselves to make sure the proper communication protocol is in place. I'm sure on the U.S. side the same thing is happening," he added.

'Airspace is national defence airspace'

The issue began when the FAA issued a notice to airmen (NOTAM) Dec.14, 2015 warning non commercial pilots about increased security measures.

"The FAA administrator hereby orders that all U.S. territorial airspace is national defence airspace," read the notice. "Pilots of such aircraft that do not adhere to procedures in the special security requirements contained in the NOTAM may be intercepted, detained and interviewed by law enforcement, U.S. Secret Service, or other security personnel.

"Any person who knowingly or willfully violates the special security requirements ... may be subject to penalties," the notice said.

Both aviation groups contacted Transport Canada to discover officials in the department had no idea the notice had been issued by the U.S. authorities.

"How come nobody knows about this," Toering asked. "How come Transport wasn't advised? How come our embassies weren't advised?

The ban meant hundreds of private business flights within Canada that passed through U.S. airspace to save time had to be rerouted to northern flight paths. Some flight schools near the border also had to cancel lessons.

The ban lasted until Jan.16 as government officials and aviation groups on both sides of the border worked together to fix the problem.

Rudy Toering, president of the Canadian Business Aviation Association reacts to ban 0:30

Many pilots were in disbelief, said Gervais whose association represents 17,000 private pilots in Canada.

"We're not at war with the U.S.," he said. "We don't have a defence zones around our countries. Why suddenly [was] this big wall between us and the U.S.?"

Major detours

Toering, whose association represents hundreds of companies and organizations including Walmart, Sobeys said it cost one company almost $30,000 to divert three business flights around U.S. airspace.

"Every single city was affected," Toering said. "Our executives and their employees are usually going to very sensitive meetings … for us it was a monetary cost — fuel, a resource cost, and an inconvenience cost that created quite a bit of disturbance for us."

To help fix the problem, the International Council of Aircraft Owner and Pilot Associations spoke to the FAA directly.

"The FAA and the agencies were trying to close a perceived loophole to ensure they knew everyone that was flying over the United States," said Craig Spence, secretary general of the council.

Bernard Gervais, president of the Canadian Owners and Pilots Association reacts 0:22

"Many U.S. pilots transit Canadian airspace," Spence said. "If this change were to happen and Canada was to say: 'Well, thanks a lot guys, guess what we're going to do to your folks. You're not going to be able to cross over our territory if you're going from Buffalo to Detroit.'

"There's a lot of repercussions that can happen if we all don't work together and they don't fully understand the impact of the decisions and some of the changes they're making," Spence added.

U.S. recognized concerns

In a statement, Transport Canada said it was contacted by pilots raising concerns and realized the notice could also affect private air ambulances and emergency evacuation aircraft.

"Transport Canada, along with Canadian industry partners, engaged U.S. government officials to review the impact of the NOTAM," wrote a Transport Canada spokesperson. "The U.S. recognized the concerns and agreed to revise as quickly as they could."

In a written response, an FAA spokesperson said it issued the NOTAM originally to comply with new international civil aviation organization guidance.

"To streamline international operations such as provisions that made it easier for aircraft, including Canadian flights … to operate within the U.S. It also provided other needed updates," the FAA said.