Boeing-owned Wisk Aero expects its pilotless air-taxi to begin carrying passengers "later in the decade" as it works with the U.S. regulator to secure approvals, its CEO said on Monday, amid scepticism among industry analysts about certification timelines.

Wisk is one of several electric vertical take-off and landing (eVTOL) aircraft makers that have emerged over the last few years with a promise to provide an environmentally-friendly mode of transport in congested cities.

But the industry faces technological hurdles such as making batteries powerful enough for companies to make more trips on a single charge. They also need to convince regulators and the public that the aircraft are safe, a barrier that is higher when the aircraft is autonomous.

Wisk is developing a four-seater autonomous aircraft that will have a range of 90 miles (145 km).

"We are right now testing and producing the elements of this aircraft that we will hope to fly around the end of this year," CEO Brian Yutko told reporters at the Farnborough Airshow.

Wisk's strategy is a departure from other major air-taxi makers, which are developing models that will require a pilot to fly the aircraft. The company has said operators of its aircraft will save on pilot costs.

But industry experts at Bain say a full autonomous passenger flight is not expected before the late 2030s and pilotless aircraft will face competition from autonomous vehicles on the road.

"Maximising passenger occupancy and avoiding return trips with empty aircraft will be crucial for operator profitability," said Mattia Celli, one of the authors of the Bain report.

Mountain View, California-based Wisk was previously a joint venture between Boeing and Kitty Hawk Corp. It became a fully-owned subsidiary of the U.S. planemaker last year.

(Reporting by Abhijith Ganapavaram; Editing by Mark Potter)