Departing flights have been grounded there Tuesday after a report of a drone sighting. Flights scheduled to depart from the busiest airport in Britain were suspended Tuesday amid a reported drone sighting near the runways -- less than three weeks after a similar incident in the area caused chaos during the Christmas travel period. The suspensions at London Heathrow Airport on Tuesday come as police have still not yet found the person or persons responsible for flying drones around Gatwick Airport in late December. "We are responding to a drone sighting at Heathrow and are working closely with the Met Police to prevent any threat to operational safety," the airport said in a statement. "As a precautionary measure, we have stopped departures while we investigate. We apologize to passengers for any inconvenience this may cause."