Private pilots have long posted ads at local airports to find passengers to chip in on costs. When a company called Flytenow moved that process online, the government put a stop to it.

A cert petition pending before the U.S. Supreme Court in Flytenow v. Federal Aviation Administration argues that grounding the start-up was “dangerously anachronistic” and could stymie the growth of other “sharing economy” services, such as Uber and Airbnb.