The promise has been titillating: quiet, electric taxis taking off vertically, floating over urban traffic. The consulting firm McKinsey says in a matter of five years, flying taxi fleets could rival airlines in size.

Well, maybe. It's already taking longer than predicted. Marketplace’s Henry Epp has been tracking the industry and its evolution.

More on this

“Electric aircraft companies are scrambling toward FAA certification as funding gets tight” from Marketplace

“The future of air mobility: Electric aircraft and flying taxis” from McKinsey & Co.