If flying cars are on your mind, you will need to wait at least 10 years before those thoughts are actually put into practice, a new study from Duke University and the NASA Langley Research Center suggests.

"Market readiness of such operations will be at least 10 years in the future," researchers said in the study conducted by Duke University's Humans and Autonomy Lab.

During Uber Elevate, a three-day summit held in Dallas last month, Uber said there could be a prototype for a flying car in the Dallas-Fort Worth area and Dubai by 2020.

But according to the study, there are major barriers, both technical and regulatory, that are in the way of autonomous aircraft being cleared for takeoff.

The main limitations for so-called 'flying' cars are a decline in the number of private pilots licensed to operate in the United States, air traffic management, the high costs and cyber security risks, the study found.

"The prospects for a practical family 'flying car' have come up short, despite consistent support," the study said.

Future of 'flying cars'

The autonomous planes companies like Uber want to roll out look more like drones and are called electric vertical take off and landing aircraft, or VTOLs. The idea is that they would fly straight up like a helicopter, then fly forward like a plane.

The fleet of electric planes Uber is working with other companies to develop would be part of a transportation network for the ride-sharing company, used by people to take them places in a short amount of time.

The problem is that they have never been certified for civil use. The military's V-22 Osprey, arguably the most advanced VTOL, has an accident rate that is nearly three times that of commercial helicopters. With a less-than-stellar safety record, it will take time before this type of aircraft can be certified as an autonomous aircraft, the study said.

History of VTOLs

The idea of a transportation network in the skies is nothing new. In 1953, the New York Airways (NYA) commercial airline company started transporting people between several heliports on buildings in Manhattan. But several crashes caused by mechanical failures put NYA out of business in 1979.

For these reasons, the study found, VTOLs need an integrated set of regulations that define how the aircraft, airspace, and general operating rules, are regulated.

Role of the FAA

The Federal Aviation Administration is in charge of all aspects of civil aviation, and would be responsible for certifying and setting the rules and regulations for 'flying' cars.

In the Duke University study, researchers noted that a backup for autonomous vehicles that would allow a pilot to takeover an autonomous aircraft could speed up certification with the FAA.

The FAA has already laid the groundwork for small aircraft, revising their Part 23 rule, which sets standards for aircraft weighing 19,000 pounds or less with 19 or fewer seats.

"We are taking a flexible, open-minded, and risk-based approach to integrating new technologies into the world's busiest, most complex -- and safest -- aviation system," the FAA said in a statement.

"We have discussed certification projects with several manufacturers of aircraft that will be flown with a pilot in the beginning, then will be converted to an autonomous passenger aircraft in the future."

NASA is also working on a traffic management system that drones and other autonomous planes would run off of, the FAA said.

Timeline for 'flying cars'

More than a dozen companies are actively working on designs for unmanned airplanes, with what the study called "extremely optimistic" timelines for them to hit the market.

Airbus, a European aerospace company, wants to test a prototype for a self-piloting flying vehicle by the end of this year.

But researchers said a more realistic timetable is at least 10 years from now, and perhaps up to 30 years to achieve full aircraft autonomy.

"Advancements for enabling technologies have had major investments and initial experimental success, but may be some years away from being deployed for on-demand passenger air transportation," the study concluded.