Air force-operated flights that transport federal MPs and senators between Western Australia and Canberra are costing taxpayers more than $10,000 per parliamentarian, per flight – five times the price of a business-class ticket on a commercial airline.

The flights, booked and approved by Defence Minister David Johnston, at times carried just three elected officials, according to the six-monthly register of VIP flights.

VIP: Defence Minister David Johnston booked and approved the special flights. Credit:Alex Ellinghausen

Finance Minister Mathias Cormann and Julie Bishop have joined Mr Johnston on the so-called "gravy plane" from the west for parliamentary sittings weeks and a cabinet meeting.

The shuttle service costs about $25,000 for a return flight, but that does not include wage costs of RAAF pilots and crew, catering and associated aircraft leasing costs for the government's Boeing 737 business jet.