Defence Minister David Johnston and Assistant Defence Minister Stuart Robert oversee the Royal Australian Air Force as part of their portfolio responsibilities and they appear to have become enthusiastic fans of its airborne service.

Between them, they notched up 14 RAAF-operated but taxpayer-funded "special purpose" flights in the first three months of the Abbott government .

Taxpayer funded flights: Defence Minister David Johnston. Credit:Alex Ellinghausen

Some flights cost the public up to $14,800 one way, according to the schedule of special purpose flights.

But research by the ABC Fact Check unit estimates a $15,000 fight actually costs the public closer to $76,000 when landing fees, aircraft leasing, crew and catering are taken into consideration.