Why do you think the Liberals would choose a Starjets 727 when the other parties are using AC? Do you think Starjets is a Liberal campaign supporter? Or are they simply trying to save money by using a Starjets 727?
The owner of Starjets is a huge Liberal contributor, hence the use of his planes. It was ironic too that the Liberals, who signed Canada onto the Kyoto Protocol to reduce greenhouse gasses, are using the biggest fuel hog for a campaign plane. They took a bit of a roasting for that.