Canberra has confirmed that it will sell 18 Boeing F/A-18 A/B Hornet fighters to Canada for an undisclosed amount.

The first two "classic" Hornets will delivered to Canada in 2019, when the Royal Australian Air Force's transition to the Lockheed Martin F-35A will be well underway, says defence minister Marise Payne.

“Australia greatly values our longstanding and broad bilateral defence relationship with Canada, and this decision is another example of our close and strong partnership,” says Payne.

“The aircraft will supplement Canada’s existing fleet as it develops and implements its plan to replace the Royal Canadian Air Force fighter jet fleet."

The transfer follows an official expression of interest from Canada in September. The package includes spares for the jets.

The RCAF requires airframes to fill a capability gap during a pending process to obtain 88 new combat aircraft to replace its 85 Boeing CF-18 A/B fighters. A request for proposals is expected in the northern spring of 2019, and a decision by 2022.

Flight Fleets Analyzer shows that the RCAF has 60 single-seat CF-18As and 25 CF-18Bs. The fighters' average age is 31.4 years, and the age range is 29.2-35 years.

Originally, Canada had planned to fill its capability gap with a purchase of 18 new F/A-18 E/F Super Hornets from Boeing. This collapsed in acrimony when the US airframer lodged a formal complaint with the US government about Bombardier's alleged dumping of CSeries aircraft in the US market.

The RAAF operates 55 single seat F/A-18As and 16 two-seat F/A-18Bs that were acquired in the 1980s. Though the type has received significant upgrades over the years, it is due to be retired by 2022 in favour of the F-35As, of which Australia has committed to 72 examples.