Recently released data shows the RAAF special purpose VIP jets used by politicians, the Governor General, visiting dignitaries and military leaders were summonsed to collect passengers on 121 occasions during the second half of 2018.

So-called staging flights are used to get the jets to where they can collect their official passengers. The Department of Defence says the fly-in fly-out model of serving those entitled to the VIP perk represents good value for money because it reduces the total number of aircraft required to provide the service.

Defence says the otherwise empty planes are also used to transport Air Force crews for training and development.

But many of flights were on routes between capital cities well served by commercial airlines. Legislation requires ministers to ensure the expense provides value for money and the special purpose jets are for use when commercial flights are not suitable.

"In accordance with the special purpose aircraft guidelines, any user other than the Prime Minister and Governor-General must justify why a commercial flight is not viable," a Defence spokeswoman said.

The RAAF VIP fleet, including three to-be-replaced Bombardier Challenger 604s and two Boeing 737 business jets, cost around $4600 an hour to operate, with a typical 36-minute hop from the fleet's Canberra base to Sydney costing taxpayers $2760. The data shows more than 130 flights between the two cities between July and December last year.

As well as a number of overseas trips, the logs also show several short trips of less than 100 kilometres, although usually as part of a series of stops by the same minister. In late December the Prime Minister's 737 flew empty from Dubai to Al Minhad airbase in the United Arab Emirates, a 33-minute drive away, before returning to Australia via Singapore. The Defence spokeswoman said there was no minimum distance for flights and the reason for the December 20 stop could not be provided due to operational security.

Entitlements to special purpose aircraft have been a regular thorn in the side for politicians in recent years. In 2015 for Liberal speaker Bronwyn Bishop made headlines by charging taxpayers $5227 to take a helicopter to a Liberal Party fundraiser that prompted a review into the parliamentarian entitlement system. During Scott Morrison's bus tour of Queensland during the last federal election the Prime Minister copped criticism after it was confirmed he and his staff had been using the VIP jets to cover large stretches of the bus's journey from the Gold Coast to Townsville.

Those with access to the use of the special purpose aircraft will soon be enjoying an upgrade, with the No 34 Squadron that operates the jets taking delivery last month of its third and final luxury Dassault Falcon 7x jets, worth about $74 million each. The new jets will replace the Challenger 604s.