The clandestine missions for a small group of air crews based in Perth in World War II were to cross perilous skies above the Indian Ocean unarmed with top secret microfiche films and people vital to halting the Japanese war machine.
As one of the pilots, Manning resident Ivan Peirce survived enemy fighters and battleships but the years finally caught up with him last week when he died aged 92.
To his loved ones, Mr Peirce is best remembered as a dedicated family man, but a few brave men of his vintage will forever revere him as a member of the wartime outfit known by the peculiar name: The Double Sunrise.
When Singapore fell in 1942, direct and, most importantly, secure communications between Australia and Britain were cut. So Mr Peirce, a 26-year-old Royal Australian Air Force navigator, was seconded in 1943 to the small outfit under the Qantas banner to attempt an aviation first - regular non-stop 6000km flights over ocean.
To restore this vital link, the men of Double Sunrise took off from the Swan River at Crawley Bay in Catalina flying boats to chew through treacherous skies for 30 hours to Sri Lanka, then the colonial outpost Ceylon where the British Empire held a tenuous foothold.
Mr Peirce's son John said his father's logbooks showed he flew the maiden mission of what would be the longest air route of any airline.
During these crossings, the Double Sunrise moniker was born as crews saw the sun rise twice on their marathon missions.
Because they could not refuel and weight meant fuel spent, the Catalinas were stripped of comfort.
In an interview more than a decade ago, Mr Peirce said temperatures sometimes plummeted to minus 14C - so cold that brushing the metal walls meant losing skin.
Guns were a luxury Double Sunrise Catalinas did without.
The sensitivity of their cargo and their vulnerability also meant they flew alone without radio contact so there were no warnings about things such as wild weather. Navigation was rudimentary, a compass and the stars, and passengers were rare but important.
In memory of Mr Peirce, Catalina Club of WA president Anthony Fell paid tribute to the brave Double Sunrise crews and their work.
"It was all very secret and we don't know a lot about what they took with them," he said. "If you wanted something sent securely, you sent it on Double Sunrise."
John Peirce said his father, who became an orchardist in Bridgetown, worked his way up to pilot and flew 44 sorties.
"It was an extraordinary effort those people put in, flying for 32 hours, those engines in your ears, with no radio contact and no guns. It would have been tense," he said. A small plaque at Crawley Bay marks where the Double Sunrise Catalinas took off and landed but to veteran flight engineer Alex Cumming, 88, the real tribute to Mr Peirce is in the impression he left.
One of the Catalina "Black Cats", crews who dropped mines and performed rescues in Japanese waters, Mr Cumming said his mate Ivan was a "thorough gentleman".
After the war, the five Double Sunrise Catalinas were destroyed, which upset the crews and meant one of WA's great wartime feats was largely forgotten.
The last Double Sunrise pilot in the Catalina Club and one of the last members of that small cadre, Mr Peirce is survived by his wife of 68 years Connie, his sons John and Ian, five grandchildren and two great-grandchildren.