A Philadelphia entrepreneur who wants to use small drones to fly advertising above the city cannot do so without authorization from the Federal Aviation Administration, an FAA spokesman said Tuesday.

DroneCast, a company formed by a 19-year-old former Drexel student, says it will use small, remote-controlled aircraft to carry advertising banners about 25 feet above the ground, according to the company's website.

But that plan flies in the face of FAA rules, which require any commercial use of U.S. airspace to use a licensed pilot, a certified aircraft, with FAA authority.

"It does not sound like it would meet those requirements," FAA spokesman Les Dorr said Tuesday. He said he did not know if the FAA has been notified of DroneCast's plans or if an effort is underway to ground the company's drones.

- Paul Nussbaum