I worked as a software engineer on the single engine "reboot" at Cessna in the mid '90s. At the time the company would pay for your private pilot's license, up to ATP cert IIRC. I knew a number of people who got their license that way. Cessna had a great ground school and a nice flying club with well-maintained planes. Ultimately, many of the people who got their license ended up not carrying on with flying. It is a very time consuming hobby and not really a practical mode of (even occasional) transportation. I now regret contributing to the single engine program (and the jets) due to the cost to the environment--I can't believe they still use leaded avgas. I read recently that private jets have at least an order of magnitude higher emissions per passenger mile than commercial.
Jets have a huge fuel consumption per passenger per mile; airliners have it lower because of the scale. GA is different, in some cases it takes less avgas to fly from A to B than driving a car. In my case, flying a Rotax 912 powered plane to my parents' house takes 2 hours and 30 liters of unleaded gas, driving takes 8-9 hours and 40 liters of Diesel, the environment is happier with me flying than driving.
It was hard to find emissions data on the Rotax 912, from a Rotax support list [1]:
>> I am looking for emissions data for the 912 iSc powerplant. I am in need of data regarding VOC and NO emissions.
> I suspect you will have to measure this yourself. I cannot think of a reason why any user outside Rotax would know this, but good luck.
even harder to find emissions on an unknown road vehicle. Lead for autos was phased out in the US starting in the 1980s. I stopped using leaded gas my 1972 VW Beetle (designed to run leaded) in the late 80s. I know some piston A/C are running unleaded, but it is glacial progress compared to cars. Having been in the industry, I am well aware of the reasons (certification/safety requirements, politics and lobbyists). I just regret in my ignorance at the time I contributed to the problem.
(I would also assume you and your parents live next to airstrips, eliminating the need to get to one.)
I think our problem is more systemic. A better question than "Do I fly or drive?" might be "Why don't I live closer to my extended family and friends?"
In fact the computer industry uses more energy than the aviation industry [2]--cryptocurrency and AI are just going to add to it. When I design software, I try to keep efficiency and utility in mind--but the human mind is good at rationalizing what it needs to. Who needs software used to repair broken tech? Hopefully more people than need single engine aircraft or jets.
Back of the napkin calculation is that burning 30 liters of unleaded gas gets you less emissions than 40 liters of Diesel; it is not only more fuel burned (with more CO2 as a result), but Diesel emissions are usually worse than gas.
The "living closer" is not an option, the place where my grandparents lived and my father was born cannot be moved. Me moving closer to the middle of nowhere (village in the mountains) is not really an option. Flying or driving there once a year is not a big deal, it is a short flight in a straight line versus a long, slow drive around mountains. The airstrip is a few hundred meters away.
Except that to my knowledge (correct me if I'm wrong) they still have non-closed loop emissions--no catalytic converter or EGR--which would mean a brand new Rotax 912 would emit more NOx, CO, and VOCs than my 20 year old Mazda gas engine car. I feel like it is my right to "rag" on something which doesn't have to follow the same rules as I do.
To be fair, my neighbors probably emit 10X the pollution running their backpack-mounted, gas-powered leaf blowers and open fire pits year round. I rag on them too, and display my rake in protest.
