Lots of talk these days in the #airtaxi crowd about billion-dollar valuations and aircraft progress “milestones.” Whenever this happens I can only think about Virgin Galactic, Icon Aircraft, Eclipse Aviation, and DayJet. Some modest perspective ... 1/x

VG at it 17 years now, with only two vehicles, and zero flown customers. Icon at it 15 years, only 100 airplanes sold. Eclipse tried an affordable business jet; DayJet a web-based based air taxi service. (Both this century!) Both are ghosts. 2/x

VG challenged by radical/complex design and multiple flight modes; Icon, despite conventional configuration, challenged by composite manufacturing and doubling of aircraft price. (Now $400k for a flying jet-ski.) 3/x

Eclipse was bolstered by innovation but ruined by making business promises it couldn’t keep; DayJet tapped IT prowess but was sunk by huge financial challenges and s-c-a-l-i-n-g. 4/x

All of this, and more, now facing electric VTOL air taxi manufacturers and providers. They say they’ll enter service by 2023, be ubiquitous by 2035, and hit $1.5t by 2040. With a whole new aircraft type AND operational model? One dependent on scale, no less? 5/x

This assumes zero setbacks and success w/: safe airspace integration, public acceptance & willingness to use, powertrain progress, low noise, simplified/autonomous operation, cert of control systems & any tilting bits, cert for passenger use ($$$), manufacturing, funding ... 6/x

None are a foregone conclusions, nor do we know about reliability, wear & tear, and charging capabilities yet. (Can barely charge electric CARS rn.) Most eVTOL companies will fail, there will be extremely public accidents and deaths, and fares will never equal an Uber Black. 7/x

Yes, electric cars and smartphones have helped reduce battery costs and boost efficiency, but cars aren’t as fussy about weight, and Moore’s Law doesn’t apply to batteries. That could be a big wall, esp if charging isn’t sorted properly. 8/x

What’s this all mean? Companies will have answers, but honestly double the timelines, triple the budgets, and buckle up for a much longer, bumpier ride than some might have you believe. 9/x

It will happen, but aviation has a long history of spanking anyone who underestimates it. In this case it’ll favor ultra-long-term investment and launch customers in cargo/industrial/military applications—where there’s lots of $$$ and lower barriers to entry. 10/x

Also, boning up on all the companies that failed before you. Aviation does reward the bold, and there’s no doubt that electrification will be massively revolutionary for air travel. I just tend to think of rn as a new Lindbergh era, not a new Uber/Amazon/Apple era. 11/11