Long before anyone was talking about the sharing economy, private pilots across the United States were already engaging in it. They used bulletin boards at general aviation airports to advertise planned trips to prospective passengers who might want to come along for the ride and share the costs of the flight.

Pilots do that because flying is an expensive hobby. The Aircraft Owners and Pilots Association warns would-be aviators to be prepared to spend more than $225 an hour when all flying costs—including fuel, insurance, and airport fees—are included. Since private pilots have to log at least three takeoffs and landings every 90 days to maintain their licenses, there aren't many viable ways to dodge those costs. So they've been sharing costs with passengers since at least the 1960s. For pilots, it's a crucial method of financing a flying habit. For passengers, it's an alternative way to reach a destination.

In the age of Uber, it has the potential to be much more. But the Federal Aviation Administration (FAA) stands in the way.

In 2014, the FAA shut down attempts to turn those analog billboards into digital ones, ruling that pilots who use online flight-sharing apps would be regulated as "common carriers" like commercial airlines. While that ruling doesn't directly ban those apps, no private pilot making weekend trips in a single-engine Cessna is going to subject himself or herself to the additional licensing and certification requirements (or mandatory liability insurance) necessary to be a commercial pilot in the eyes of FAA.

In the wake of the agency's ruling, one of those just-launched apps, FlyteNow, took the federal regulator to court. But last year the U.S. Supreme Court declined to take the case, seemingly grounding the apps for good.

Now Congress has an opportunity to overrule the FAA.

"A personal operator or a flight operated by a personal operator does not constitute a common carrier," reads part of the Aviation Empowerment Act, a bill introduced today by Sen. Mike Lee (R-Utah). The legislation maintains the current prohibition on private pilots making a profit off flights offered via flight-sharing apps, but it would otherwise allow for the creation of digital billboards advertising trips.

"Innovation is key to competition and accessibility," Lee told Reason. "Studies and experience with cost-sharing services have proven to be safe and effective in other countries, and it is past time we enact them in our country as well."

Allowing flight-sharing is a win-win for aviation enthusiasts, whether they are pilots or just enjoy flying. And the small number of private planes and pilots, along with those rules against letting noncommercial pilots earn a profit for their services, means that flight-sharing is unlikely to disrupt commercial airlines in the same way that Uber disrupted the taxi industry. Almost everyone has a car; very few people own private aircraft.

Apps like Flytenow and AirPooler launched in 2013, not long after Uber was becoming a ubiquitous part of non-airborne transportation. Naturally, the apps were often referred to as "Uber for the skies" as the subsequent regulatory and legal battled played out.

But that characterization is not entirely accurate. Unlike Uber or Lyft, these flight-sharing apps intended to do nothing more than the bulletin boards in general aviation airports: They connected pilots and passengers for the purposes of sharing the cost of a flight. Unlike with the ride-sharing services, no one was earning a profit—that, they feared, would violate the FAA's rules.

In other ways, the apps did resemble ride-sharing services. Pilots and passengers had individual profiles, and a ratings system provided feedback for other users. Running the current bulletin board network through an online app is likely to increase transparency and safety for all involved, even as it opens up the practice to a larger pool of people.

In a 2017 paper for the Mercatus Center, Christopher Koopma blamed the FAA's ban on the fact that Congress failed to clearly define what constitutes a "common carrier." Without any definition in federal statute, the agency was left to make its own definition, which it did in 1986 by creating a four-part test.

Before flight sharing apps like FlyteNow launched, developers approached the FAA to make sure they were staying on the right side of the law. Asking permission might have been a mistake. Acting on their own authority, the FAA used their own common carrier test, ruled the apps to be effectively the same as a commercial airline, and "imposed a significant limitation on the right of private pilots to engage in cost-sharing to which they would otherwise be entitled," wrote Koopman.

"According to the FAA, it is perfectly okay for strangers who meet over a physical bulletin to share a flight, but if those same people meet online, where flight-sharing services such as Flytenow offer verified identities, then the flight magically transforms into an illegal commercial operation" FlyteNow co-founder Alan Guichard told Forbes shortly after the FAA grounded his app.

In other words, the battle over flight-sharing has followed a predicable arc familiar to anyone who has watches the interplay between Congress and the executive branch on a host of subjects, from health care to the environment. Congress passes a broad, ill-defined statute and leaves federal regulators to create specific rules within that standard. When the resulting rules do not comport with congressional intentions, lawsuits are launched. The courts usually side with the regulators, because Congress granted them the authority to make those rules.

"The problem here is that Congress has granted an incredible amount of authority over the decades to the FAA," says Marc Scribner, a senior fellow at the Competitive Enterprise Institute. Lee's bill, Scribner says, is exactly the type of thing Congress should be doing more of—clarifying in statute how regulatory bodies should be engaging innovative developments in the marketplace. "This is a job for Congress, not for the regulators," he says.

The FAA could decide on its own to pull a 180 on flight-sharing—or could be ordered to do so by President Donald Trump or Transportation Secretary Elaine Chao. But congressional action would have the most lasting impact, and would provide important clarity to the question of what constitutes a common carrier for the purposes of FAA regulation, something that may factor into future developments in air travel.

The longer Congress waits to act, the further American air travel will fall behind the rest of the world. Wingly, a flight-sharing service that allows pilots to post upcoming trips and allows passengers to request them, is already active across Europe. You can book a private flight from Liverpool to London, for example, for less than £60. Pilots can offer sightseeing trips in addition to one-way travel. "Join me as we laugh at the cars stuck on the M25″—a major highway around London—says one current ad.

It's not hard to imagine a similar service taking off in the United States. If the FAA won't let that happen, perhaps Congress will.