Makers of new air transport technology such as drones and air taxis are joining with established aviation companies including airlines and helicopter operators to help secure backing from regulators. They face similar challenges, notably how they can be operated safely over urban areas. Proponents maintain they are cheaper and more environmentally friendly than cars and taxis, even if routine consumer deliveries and rides remain years away. "We don't know what's going to work and what's not," said Mesa Chief Executive Jonathan Ornstein. Phoenix-based Mesa plans to start with four drones made by Flirtey Inc. of Reno, Nev., with options on another 500 over the next four years to expand the service in the U.S. and to New Zealand.