Rebreather Diving Test Pilots

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Lessons Learned from a Near Miss

In 1997, I bought a Cis-Lunar MK5P rebreather to prepare for a United States Deep Caving Team Project in North Florida. With no formal training available, we early adopters became test pilots, figuring it out as we went diving. Looking back, I’m lucky to have survived the learning curve.

In our scuba shop classroom, Australian colleagues Andrew Poole and John Vanderleest joined me to explore various rebreather failures—especially hypoxia. John had blacked out underwater once due to a restricted oxygen flow and was only saved by Andrew’s quick reaction. That incident stayed with them. We wanted to know—could a diver detect the problem in advance and prevent a blackout?

We set up a voluntary experiment: Andrew would wear a disabled MK5P rebreather, with oxygen slowly depleting, and try to record symptoms before blacking out. The goal was to see if he could recognize hypoxia and switch to bailout gas in time.

He never made it. Despite noting symptoms like tingling, Andrew became unresponsive at a PO2 of 0.12. His hand spasmed, and he slumped forward. We pulled him off the loop and hit him with oxygen, causing a mild seizure. He recovered, confused but completely unaware he’d lost consciousness.

Weeks later, I had my own scare. Alone in Devil’s Ear Cave, I was experimenting with manual oxygen control while hiding the display. I wanted to know if I could get home from the back of a cave with no sensors, no displays, or any electronic means of monitoring PO2. For nearly six hours, I swam around the cave flushing with diluent gas and then practicing a technique called minimum loop volume. At the end of the dive in shallow water, the PO2 dropped while I lost concentration. Mere meters from exiting the water, I felt a black curtain encroaching on the edges of my vision. I woke up, threw the loop into open circuit, and pulled the wool sock off my handset. The PO2 was down to .11. I could have drowned in the shallows an arm’s reach from the stairs but instead developed an enduring respect for guarding against complacency.

Both incidents were clear warnings: hypoxia is insidious, and ego or overconfidence can be deadly. We eventually developed safer training methods, but the lessons were learned the hard way.

Here is a video of that classroom experiment. You’ll be able to see me with my young, long hair:

Turning Challenge Into Change: A Brighter Future Is Within Reach

The world today stands at a crossroads. With rising global temperatures, economic uncertainty, social unrest, and lingering anxiety, it’s easy to feel overwhelmed. But in every challenge lies opportunity, and if you are an optimist like me, you recognize that we are living in a time of great potential.

The difficulties we face are real. But so is our capacity for resilience, creativity, and compassion. In the face of anxiety, we can discover the power of collective action. In the midst of division, we can listen, empathize, and unite. Sitting at home is not an option. We have to be very public about the type of world we wish to live in.

This moment does not have to be a breakdown—it can be a breakthrough.

Business as usual is no longer sustainable. We can reimagine how we live, grow food, share resources, and care for one another. Innovations in clean energy, regenerative agriculture, and circular economies are gaining momentum. Young people are becoming activists and entrepreneurs, and citizens around the world are casting votes with the future in mind.

We have the tools, knowledge, and, increasingly, the will to build a just, sustainable, and green world. It starts with small acts: choosing ethical products, supporting local communities, speaking up for what matters, and believing that our choices count—because they do.

This week’s election in Canada has given us hope and agency. We may be building a different world, but we are determined to build, work and not sit idle watching things collapse.

Today’s uncertainty is an invitation to reimagine our future, invest in one another, and leave a legacy of hope. The path forward will not be easy, but it will be worth it.

Are you ready to be part of it?

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Canada News

In case you blinked and missed it, we just had a federal election in Canada. Most of the world usually snoozes through our political process, but this time, thanks to the American President threatening our sovereignty and slapping tariffs on our products, many people who live in places where it does not snow eight months of the year were paying attention.

Without turning this into a Canadian political science essay, like much of the world, Canada has a Parliamentary form of government. In this election we had five viable parties and really just two possible outcomes - either the Conservative Party of Pierre Poilievre, or the Liberal Party led by Mark Carney - would win the most seats in the House of Commons, and therefore become Prime Minister. The Liberals came out ahead and Mr. Carney will lead Canada for the foreseeable future.

Above: Jill Heinerth receives the Honorary Ottawa Riverkeeper award from previous Riverkeeper, and new Canadian Prime Minister, Mark Carney.

Mr. Carney is an Oxford educated economist, and formerly the Governor of the Bank of Canada, and the Bank of England. He knows a few things about international trade and finance. Many Canadians say they voted for Carney’s Liberal Party (we vote for our local Member of Parliament, not directly for PM), because they believe he is well suited to sit across the table from Donald Trump and negotiate a good deal for Canada. Carney is a stable, serious, down-to-earth man. He also is steadfastly opposed to any form of Canadian capitulation towards Trump’s threats and mockery.

Above: Mike Myers shows his True North roots on a recent episode of Saturday Night Live.

Canadians seem to be engaged and united as never before - and just maybe this year will see an all-Canada NHL Stanley Cup Final!

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Robert’s Perfect Song - “I Try” by Macy Gray

In recent newsletter’s I’ve been sharing music videos of songs that I consider “perfect”. You may be familiar with some of them, like Kate Bush’s “Running Up That Hill”, or Talking Heads’ “Life During War Time”. Or, maybe you are being exposed to something for the first time like Sophie Ellis-Bextor’s “Murder On THe Dance Floor”. Either way, I hope you enjoy these little musical interludes.

If you had a pulse and a radio at the turn of the century, you most certainly heard Macy Gray’s “I Try” on heavy rotation in 1999. And the music video of the song won the MTV New Artist of the Year award, so you probably saw the cinematic sequence of Ms. Gray waking up in a New York hotel room, buying flowers, and traveling via transit to meet a man in a park - only to realize it was all a dream and she never left her room. (Okay, music video director’s were running out of plots after about 1995).

“I Try” charted at #1 in Australia, Canada, Ireland, New Zealand, UK, and USA. The song also won a Grammy for Best Female Vocal Performance, and was nominated as Song of the Year. Not bad considering that just a year before, Macy Gray was a student at UCLA, working as a cashier at a Beverly Hills boutique, and writing songs for her friends and occasionally singing at Los Angeles jazz clubs.

I highly recommend you listen to Macy Gray’s debut album “On How Life Is” - A good candidate for a “Perfect Album. Not a bad song on it. No fillers, just one gem after another. You can get the CD here.

And, as always, please share the music you love with young people who may not know that there was actually good singing before auto-tune.

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No matter where you find yourself this week, remember to be kind and generous. There are many of our sisters and brothers who are, through no fault of their own, facing hard times. Above all - LOVE ONE ANOTHER!