A British Airways aircraft takes off from Heathrow Airport in London in 2010. (Andy Rain/European Pressphoto Agency)

This is a worry of every pilot flying into Washington’s three airports and those around the globe.

British officials are investigating whether a drone collided with a British Airways flight as it attempted to land at London’s Heathrow Airport.

The incident happened Sunday afternoon as the flight from Geneva attempted to land, the BBC reported. The plane with 132 passengers aboard landed safely, but once on the ground, the pilot reported that an object, which he thought was a drone, had struck it.

Airport police have launched an investigation into the matter, which if confirmed would be the first known case in the United Kingdom of such an encounter.

The BBC noted:

A Civil Aviation Authority (CAA) spokesman said it was “totally unacceptable” to fly drones close to airports, and anyone flouting the rules can face “severe penalties, including imprisonment.”

Steve Landells, from the British Airline Pilots Association (Balpa), said it had been “only a matter of time before we had a drone strike.” He called for greater enforcement of existing rules.

Flying a drone near an airport can already be punished with up to five years in prison, and rules also forbid taking them above 400 feet (122m) or near buildings and crowds of people.

CNN reported that there have been a growing number of  “close encounters” between airplanes and drones in the U.K., according to the Airprox Board, which tracks airline safety. There were 23 such incidents between April and October 2015, and the board classified at least a dozen of them as “presenting serious risk of collision.”

A Washington Post investigation also found a growing number of encounters between drones and aircraft. Between January and August of 2015, nearly 700 incidents were reported — about triple the number recorded for all of 2014.

The U.S. Federal Aviation Administration requires owners to register the mini-aircraft, which have proved to be popular gifts. The Consumer Electronics Association estimated there could be as many as 700,000 new drone owners by the start of 2016. Drones that weigh between a half-pound and 55 pounds must be registered. FAA officials said part of the goal of the registry is to create a system of accountability.