The government announced in its March budget that the plane would be sold to reduce costs.
But Liberal Transportation critic Bill Fraser said Wednesday he doesn't see how the government will save money by keeping a charter service on standby.
"I would say that this service is going to cost us more than we're currently paying," Fraser said. "There's a hangar at the airport that has a 20-year lease that still has to be paid ... so we don't know where the efficiencies are being found."
But Transportation Minister Claude Williams defended the plan, saying the government isn't going to enter into an agreement that would cost more.
"It's going to be a cost saving for taxpayers, and at the same time we're going to be able to rely on a charter service which is essential to carry on government business," Williams said.
Use of the government plane has been on the decline. According to figures from Williams' department, the government used the airplane for 278 hours in 2011-2012, and about 200 hours in 2012-2013.
When the government issued a request for proposals in May for a charter service, it said it expected to require about 100 flight-hours each year.
Three companies have submitted bids for a five-year contract to provide charter flights for the provincial government.
They are CanLink Aviation of Dieppe, N.B., Capital Airways Inc. of Fredericton, and Strait Air 2000 Ltd. of Quebec City in a joint venture with the Madawaska Maliseet First Nation in New Brunswick.
The joint venture also submitted the lone bid to co-ordinate the sale of the King Air B200 aircraft.
A second bid was disqualified.
Williams said the plane is worth about $3.8 million.
Fraser said he's concerned the Opposition and media may not be able to get the flight manifests and the costs for each charter one the flights are being managed by a private company.
"The departments are going to be chartering their own service so it won't all be through the Department of Transportation and Infrastructure like it used to be where they provided lists of where the plane went, who were the passengers on the plane, what was the purpose of the trip, and what was the cost," he said.
But Williams said the charter company would be required to file a monthly report on government flights, and the report would be made public.
He said the Opposition can ask the departments for the information, and the expenses for the premier and ministers are posted each month online.
"It will still be open and transparent," Williams said.