Sitting at the home he has had specially built in Whangarei, its doorways wide to accommodate his wheelchair, and with views over native trees and shrubs his friends and caregivers have planted in the garden, he says he's replayed the moment in his mind many times.
"I remember lying there, trying to move things. It was just confirmation of what I knew had happened. I'd landed on the top of my head with my feet pointing up at the clear blue sky, pirouetted on my head and dislocated two vertebrae 100 per cent and crushed another."
The previously active 52-year-old was left with no sensation anywhere below his armpits and only limited movement in his hands. His condition will never improve.
That day was the beginning of a huge struggle. Brown quickly contemplated suicide.
It's detailed in the book, This Way Up. "I had to go through writing a couple of chapters that were very difficult to relive. Writing about the initial aftermath of the fall, and the entire stay in the spinal unit where I could see no hope, no future. I didn't know where I'd live, who'd look after me, what job I'd do. There was almost insurmountable worry."
In the book he says he twice drove his wheelchair to the side of the busy road outside the Otara Spinal Unit and contemplated rolling out in front of a vehicle. He describes how he asked his son to bring in his gun and how he thought about trying to fall out of a window. "Three times I set myself up to commit suicide and didn't go through with it."
His battle was made even more difficult when his wife of 31 years, Sandra, called an end to their marriage by phone six weeks after his fall. "She didn't cope with the accident well at all. While I was in the spinal unit, she told me not to come home when rehab finished. So I dealt with that and the fall in pretty close succession."
Brown admits he wasn't always the perfect husband. He'd had an affair about 10 years earlier and says there were "cracks in the marriage I wasn't addressing", but he says it was still a difficult blow.
"I had to adapt to strangers performing personal care, rather than a wife or partner. Also, I was separated at the very time I needed a rock to depend on. So, being newly paralysed and separated came as a gigantic double whammy."
Because there was no home to go to, when he was ready to leave the spinal unit he had to check into a rest home in Whangarei where, for 2 years, he was forced into the routines of the elderly and listened as they "died of sadness" around him.
Today, he lives in his own home, helped by caregivers. Writing the book has helped, too, though even that had difficulties. The first draft of 155,000 words was written in 12 weeks, typed with his right thumb: the only digit he has enough control of to master the keyboard.
He relies on four caregivers who work a seven-day, 24-hour roster, taking care of his showering, dressing and even turning in the night.
"They become good friends; they do the housework. I do a bit of dusting but they prepare most of my meals."
Surgery on the tendons in his right hand has given him more movement and he can clean his teeth, shave and brush his hair. But everything else must be done for him.
He says the men in the Otara Spinal Unit lament the loss of their sex lives. Brown says he is still single, although he has a "special girlfriend". Romantic moments can be difficult. "Various oral and injected drugs will produce an erection. [Tetraplegic men] will have an orgasm but not feel it. We are taught that for walking people, sex is 95 per cent physical and 5 per cent emotional. We are told to reverse those figures. My partner never complains and, you know, just loving, snogging, touching is reward and enjoyable enough."
It's that sort of honesty that has upset his family. His children are refusing interviews and he says it was an achievement to get them to contribute the one paragraph each added to his book's epilogue.
"I'm a bit out of favour with them over the book, especially my daughter regarding the death of Abigail [Brown's granddaughter, who was stillborn and whose death is detailed in the book]. But hey, do I care? No. they'll come around. My son-in-law is fine and he's working on Belinda [his daughter] for me."
He says the book was something he'd wanted to do for a while. "No matter how far down you are it is possible to rise above it."
Talking to Brown gives an insight into how perceptions change. He waves off having his bowel manually stimulated by a caregiver, dropping things and falling out of his chair. Other things appear more significant.
"My heat receptors don't work so I have difficulty differentiating hot and cold. In the sun I can't feel my core body temperature rising so I can get heat stroke. In winter, I would probably feel doubly cold to the average person. I wrap up with clothes that probably don't seem appropriate."
In the shower, he can only feel warm water on the parts of his body that still have sensation. "To this day I do not enjoy being showered and only do it because I do not want to become a smelly old man."
Because he suffered his injury while on a building site, Brown now speaks to workers and management at businesses where there is a risk of serious harm. He says his speeches are received very well. "I get a breathtaking reaction."
He'll get a similar reaction from those who read the book. "One friend said it's like having sex in a sandpit, fun but gritty."
At one point he describes how he and another patient hooked their wheelchairs together with rope so he could tow his friend inch-by-inch to a nearby pub, and how returning down the steep driveway, post-beers, was done without a second thought. It's moments like that he thinks people will find inspirational.
"If you allow it, good things will come out of that situation. And that's the best part, because you are given a second chance, a new beginning, an opportunity to reinvent yourself. Shit happens, but so does magic."
Brown is publishing This Way Up himself. It is on sale this month from www.rhettbrown.co.nz. It will be stocked in Paper Plus Whangarei, and may appear in other outlets around the country in coming months.
