Uber may have only just begun real-world testing of its self-driving cars in Pittsburgh, but the company is already looking towards what it thinks is the next step in urban mobility: VTOL airplanes.

VTOL, which stands for Vertical Takeoff and Landing, has been used in military designs since the 1960s, when the Harrier jump jet first took off. But no engineers have successfully adapted the technology—designed for multi-million dollar fighter jets—to Cessna-sized airplanes for commercial use.

Uber thinks it can. The company's products head Jeff Holden told Recode over the weekend that autonomous VTOL aircraft could be flying around cities within a decade.

The concept is similar to what hyperloop companies propose for augmenting overburdened subway and commuter rail systems: add strategic, high-speed, personal transportation links between areas of the city that are underserved by conventional modes. The big difference with VTOL, of course, is it requires far less infrastructure.

Holden envisions using the roofs of buildings as makeshift airports, reducing congestion on the ground. Like UberPool, VTOL planes would carry groups of people going to nearby destinations.

Uber has offered helicopter service before, linking New York City with the Hamptons on Long Island, for example. But those efforts have mostly been expensive, temporary marketing gimmicks. The advantage of VTOL planes, which have fixed wings instead of rotors, is that they are in theory cheaper to operate.

Holden didn't elaborate on the details of Uber's VTOL research. But Uber isn't the only one working on adapting the military technology for commercial use. A company called Aurora Flight Sciences won a contract in March to work on an experimental VTOL plane for the Defense Advanced Research Projects Agency (DARPA). Aurora has already developed a 325-pound scale model of its design, which it says could be useful for unmanned cargo deliveries in war zones.