British police are investigating what could be the first known case of a drone colliding with a passenger aircraft, after a pilot told authorities that he believed his jet hit a drone as it flew into Heathrow Airport from Geneva Sunday.

"The flight landed at Heathrow Terminal 5 safely," police say. But they add that "an object, believed to be a drone, had struck the front of the aircraft."

Metropolitan Police officers are looking into the incident, which has prompted statements from both the British Civil Aviation Authority and Heathrow Airport calling for drone operators to follow safety rules and avoid commercial aircraft.

"It is totally unacceptable to fly drones close to airports, and anyone flouting the rules can face severe penalties including imprisonment," the CAA says. The agency also says that it expects British Airways to share its report about the incident within 72 hours.

In its statement, Heathrow Airport called for the government to institute stronger regulation and enforcement.

The incident occurred around 12:50 p.m. local time Sunday — a day that was reportedly cloudy and marked by light rain in London.

While stressing that its plane landed safely, British Airways also said it is helping police with the investigation. The airline says that its engineers gave the plane a full examination and cleared it to fly without an interruption in service.

News of the apparent drone collision comes just days before the U.S. Federal Aviation Administration is to hold an industry symposium about integrating the growing number of unmanned aircraft into U.S. aviation rules and protocols.

The FAA recently instituted mandatory registration of Unmanned Aircraft Systems for anyone who owns a craft weighing between more than 0.55 pounds and less than 55 pounds. The drone's owner is required to be a U.S. citizen who's 13 years of age or older; the registration, good for three years, comes with a $5 fee.

In the six-month period from last August to January, the FAA received 583 reports of pilots spotting unmanned aircraft, according to the agency's latest release of data.

In the highly restricted airspace around Washington, D.C., it's illegal to fly a drone within a 15-mile radius of the city, according to the FAA's rules. A number of U.S. cities and states have enacted their own bans or restrictions on drones.

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