The cost-cutting Conservatives are not ruling out selling off some government aircraft — including the controversial fleet of Challenger jets.

Documents obtained by the CBC’s Power & Politics under access to information show the executive aircraft were used only seven times by cabinet ministers in the one-year period between May 2011 and April 2012.

The military used the planes most frequently — including transporting brass such as Chief of Defence Staff Gen. Walt Natynczyk, carrying out international training exercises and participating in air shows. The jets were also used for three runs for children who took part in the Canadian Forces Family Day.

In all, the military used the aircraft 190 times, compared with 50 trips by Gov. Gen. David Johnston and 41 by Prime Minister Stephen Harper.

Cabinet ministers using the aircraft in the one-year period were Finance Minister Jim Flaherty, Defence Minister Peter MacKay, Natural Resources Minister Joe Oliver and Health Minister Leona Aglukkaq.

The aircraft, which cost about $10,000 an hour to fly when all variable and capital costs are added to the staff and operations, have been dogged by controversy and dubbed "flying limousines" and "aerial offices."

Julie Vaux, a spokesman for the prime minister, said the use by cabinet ministers is down dramatically since the Conservatives took office, and that ministers are instructed to travel on government business at a "reasonable cost to taxpayers."

"This is part of our culture as a government, and it has allowed us to reduce ministers’ use of Challenger aircraft by over 80 per cent compared to the previous Liberal government," she said. "The former Liberal government cut $20 billion from Canada’s defence budget, but the Liberal ministers bought brand-new Challenger jets for themselves."

The ministers are leaving the pricey planes on the tarmac, so will the government unload all or part of the fleet?

"We have sold eight Transport Canada aircraft since 2009 and are looking at whether additional government aircraft should be sold," Vaux said.

Appearing on Power & Politics, Andrew Saxton, the parliamentary secretary to the Treasury Board president, noted the Challenger aircraft were "inherited" by the Conservatives from the previous Liberal government, and that the auditor general had flagged problems with the purchase in past.

Although the military is using the aircraft for important business, repatriation and medical evacuations, Saxton said, it doesn’t make sense for the costly planes to be sitting idle on the tarmac.

"We’re always looking at ways of saving taxpayer dollars and assessing our needs," he said.

NDP treasury board critic Mathieu Ravignat said the government must review the number of jets in the fleet, especially in a time of restraint.

"We’re asking Canadians to make sacrifices with regard to the services they get from government with the cutbacks that are occurring," he said.

Liberal treasury board critic John McCallum agreed and called for a study of the need for the planes.

"We are in a period of restraint, the government is making cuts to environmental research, and to other things that Canadians really need like search and rescue, so if we can economize on the use of these jets and maybe reduce the size of the fleet, maybe that would be a good idea," he said.