Seventy-five aircraft are to fly over the Blue Mountains in eastern Australia on Saturday to mark the first crossing of the range in 1923.
The flyover on Saturday celebrates the crossing of the mountains by Gregory Blaxland, William Lawson and William Wentworth.
AAP reports there will gyrocopters, warbirds, Cessnas and an RAAF Hercules. Eleven sites have been set up for spectators along the route.
The fleet starts from Emu Plains at 11.30am (AEST) and is due to fly through the Blue Mountains to Mount York, before heading to Bathurst.
Descendants of each of the three explorers will take part as passengers.