Air carrier flight crew reported observing an object pass by the aircraft; followed by a metallic impact noise during arrival descent. After landing; the flight crew found a mark on the aircraft which they suspected could have been caused by collision with a UAS.
Synopsis
Air carrier flight crew reported observing an object pass by the aircraft; followed by a metallic impact noise during arrival descent. After landing; the flight crew found a mark on the aircraft which they suspected could have been caused by collision with a UAS.
Narrative
Conditions were Night VMC; clear sky and unlimited visibility. While descending via the Hyper9 Arrival and passing over the 'MOWAT' waypoint passing through 5;700FT I and my FO observed an object I would estimate to be 2ft in diameter suddenly appear in the left wing landing light beam and pass between my side window and the engine nacelle. This was accompanied with a metallic impact noise which was heard by the FO as well. No warning or caution lights came on after. No adverse indications or handling of the aircraft was observed. After a brief discussion with the FO on what we saw the flight continued and parked at the gate normally. I did a post flight inspection of the area I saw the object pass (inboard wing root). I found a triangular shaped black mark on the left inboard leading edge of the wing about 1.5ft from the wing root and before the landing light lens. I asked the FO if that mark had been on the wing during the preflight in ZZZ; the FO said that mark was not on the wing prior to flight. I called Maintenance Control to inquire if there was any long history of that mark on the left inward wing. Maintenance Control could not locate any previous write up regarding that issue in that location. I made an ELB entry for MX and followed up with emailing the photo I took to the Maintenance Control. Phone calls with the Chief Pilot and ATC supervisor were also accomplished and a copy of the photo I sent to Maintenance Control was also send to Person A per his request. The termination checklist on aircraft # was accomplished per Station Ops request and I and the FO departed for the hotel.
Second reporter narrative
We were on the hyper 9 arrival into IAD runway 1 R transition. While on descent from sigbe to mowat at 5700 ft the captain and I saw something zip by the cockpit under the captain's side window and a small thud was heard. We could not make out what it was because it was night time and the lights from the aircraft shined right on it. We made sure the aircraft was fine and it was with no reports either from the flight attendants. I myself could not make out what it was for it looked like a blur and flew by the captains side quickly. The captain thought it was a drone but not entirely sure. We both could not give any complete description of it for it passed by so fast. Once on the ground safely the captain did an inspection of the aircraft and found a scuff on the left wing leading edge near the wing root that was not there when I did the walk around in ZZZ. He took the picture and talked to maintenance.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.