A passionate aviator, one of Mr Williams’ logbooks recounted a time he had flown one of his custom-built aircraft through the Lindis Valley, and subsequently crashed it.
"His log just said, ‘rising ground and no room to turn’," Eyers said.
"In other words, it was the ground’s fault, not his fault."
Rising Ground; And No Room to Turn tells the story of Mr Williams’ three-decade journey designing, building and flying four aircraft across Otago, none of which were ever certified by the authorities.
Ms Eyers said work on her first book began as a family project six years ago, but expanded as she realised just how much information her brother had left behind after he died in 2002.
"He didn’t hoard material possessions but he hoarded every letter, every piece of paper, everything in his logbooks, the communication he had with the Civil Aviation Authority (CAA)."
She believed Mr Williams’ decision not to go down a more orthodox pathway was due to factors including shortsightedness, but also a determination to experiment with aircraft on his own terms.
"He really wanted to design his own aircraft and build them."
Ms Eyers could not fully explain how her brother had managed to test home-made planes for 30 years without being seriously injured, but said his patience, creativity, attention to detail and some element of luck probably had a lot to do with it.
As for the law, rumours swirled at the CAA of a mysterious craft in the skies of Otago, yet even when they caught up with Mr Williams their words had little effect.
"He got tracked down and interviewed, then he got sent a few letters, and he got told to dismantle the aircraft. But at that stage the engine had seized anyway, and so it was already not flying.
"And he kind of knew that. He let them send him a few letters before he agreed that he wouldn’t fly it again.
"So he started on Mark III."
Ms Eyers said she was not sure whether she would continue writing, but admitted her research also uncovered a lot of information on her late father, a teacher and a Lancaster pilot in World War 2.
"Well it feels like with all of Dad’s resources, there’s a story there. I’ve never tried fiction but I don’t think I can go to fiction. I might stick to the biography stuff."
Rising Ground; And No Room to Turn is available now.
By Regan Harris