The recent London Heathrow airliner incident striking a drone on approach indicates as most thought. Birds, hail and other aircraft are much more likely to damage an airliner than a small drone weighing less than 3 lbs. Maintenance found no damage and returned the aircraft to service immediately at the gate after a visual inspection. Even the cockpit windows are tested for large bird strikes during certification. An engine ingestion of a drone may cause some damage but nothing like a large bird. Most drone operators know the rules about flying under 400 ft and staying clear of airports. Most drones with their GPS will not fly into these restricted areas and won't even take off if you attempt to take off inside one. After being retired from a major airline and enjoying my P3 photo shoots I understand both sides quite well. Most airline pilots have a lot more important things to think about than a drone hitting their airplane. Lightning strikes, turbulence, fuel, weather and bad crew meals come to mind.