It's arguably the most expensive and technically complex piece of headgear ever produced and before any Royal Australian Air Force pilot steps into the cockpit of the new F-35 Joint Strike Fighter (JSF) jet, they will need to be fitted with a custom-made $770,000 flight helmet.

With the Australian government committed to purchasing 72 of the controversial fighters at a cost of $12.4 billion, the bill for these smart helmets alone could exceed $55 million.

And that's if there is only one pilot per aircraft, although typically an air force will train more pilots than there are jets in a fleet.

Packed with electronics and sensors, the 2.25kg carbon fibre-shelled Helmet Mounted Display System (HMDS) pumps observational data into the helmet, turning the visor into a display screen that sits millimetres from the pilot's face.