Five years after DayJet’s on-demand air service using very light jets ceased operations, the dream of air taxis remains alive. But industry is looking at unmanned aircraft technology as a way to reduce or eliminate the pilot costs that contributed to DayJet’s demise.

A commercial airline can require up to 19 pilots for every aircraft, says John Langford, CEO of UAV specialist Aurora Flight Sciences. DayJet reduced this to four-five per aircraft, but the need for two pilots in each of its three-passenger Eclipse 500s drove its costs.

“We need to get that down to around two pilots per aircraft,” he told the American Institute of Aeronautics and Astronautics (AIAA) Aviation 2013 conference in Los Angeles on Aug. 14. “That’s where UAV technology comes in. We can go from two to one in the cockpit.”

Optionally pilot aircraft technology, which Aurora has developed for its Centaur version of the Diamond DA42 light twin, can cut crew costs in half, to around 15% of operating expenses, he says.

Today’s aircraft is designed for data collection missions, but Langford envisions a “Centaur II” emerging within 3-5 years and capable of cargo delivery and air taxi operations. This would be certified for single-pilot operations with passengers and as a UAV for cargo flights without occupants.

In 7-10 years, at the earliest, a “Centaur III” could emerge that is designed for personal transportation and certified to operate as an unmanned aircraft in national airspace carrying passengers. Centaur IIIs would be controlled from a network operations center, he says.

In a even bolder vision, the Comparative Aircraft Flight Efficiency (CAFE) Foundation is proposing a five-year series of prize challenges that would lead to development of an autonomous Sky Taxi able to operate on demand from “pocket airparks” inside communities.

CAFE organized the 2011 NASA Green Flight Challenge, in which the winning aircraft for the $1.35 million prize exceeded the equivalent of 200 mi. per gal. per passenger on battery power. CAFE Executive Director Brien Seeley is now trying to drum up support for the follow-on Sky Taxi challenges.

The series of annual prize challenges would develop and demonstrate technology for a quiet, electrically powered, extreme short-take-off-and-landing (ESTOL) two-seat aircraft able to operate autonomously and safely on short flights from small airfields close to users.

Beginning with competitions to develop electric wheel motors for taxiing and takeoff, and quiet propellers, the series would culminate in the demonstration of a quiet, autonomous ESTOL Sky Taxi, Seeley told the AIAA conference.

The air taxi would fit within the weight and performance limits for a two-seat light sport aircraft, with a stall speed of less than 32 mph. and top speed above 120 mph. A high lift-to-drag ratio wing would extend glide performance to improve safety.

Wheel motors would be used to increase acceleration and achieve a 90-ft. ground roll to a 45-mph. takeoff speed. Takeoff noise with a 600-lb.-thrust propeller would be less than 60 dBA, keeping any nuisance well within the 500 X 250-ft. perimeter of the airpark.