Date: 201811
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Taxi
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Situational Awareness
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Ground Event / Encounter Aircraft
Detector: Person Flight Crew; Person Ground Personnel
When detected: Taxi
Result: Aircraft Aircraft Damaged
Contributing factors: Human Factors; Procedure
Primary problem: Human Factors

Narrative: On the taxi in to our assigned gate we noticed that the aircraft [in an adjacent gate] was not a Company aircraft; so it immediately peaked our attention as we passed by on the way to our assigned gate next to the other aircraft. We made the left 90 degree turn to line up on the Safety Zone taxi line. I noticed the proximity of the other aircraft's left winglet and stated out loud to the FO (First Officer) that it appeared as though the other aircraft's winglet was encroaching on our Safety Zone. We stopped our aircraft and discussed the situation. We were at a 45 degree angle to the wing tip and the left-hand Safety line; so we had a bit of parallax. There was a Ground Agent standing; what appeared to be directly below the winglet of the other aircraft. There were also three orange cones and a ladder lined up with our left Safety Zone line. We felt as though the person was there to help ensure that we were entering the Safety Zone with the proper clearance on the other aircraft. We transitioned our sight out the front windscreen to the marshaller and the other personnel stationed directly in front and off to each side of the nose for what we assumed was for the Safety Zone clearance. The marshaller started moving the wands to bring us into the parking area so we proceeded very slowly because we wanted to make sure that we had the proper Safety Zone clearance. As we started to move I referenced the ground personnel over my left shoulder one last time and then turned to concentrate on my lineup and the marshaller. About the time I did this the FO forcefully yelled for me to stop the aircraft. I applied the brakes expeditiously and brought the aircraft to a stop. I immediately turned to look at the left wing tip and realized we had struck the winglet of the other aircraft with our left winglet. We set the parking brake and began to manage the situation. We shut down the motors and worked with Operations; Dispatch; and Maintenance to deplane the aircraft via air stairs. One of the ground personnel informed the FO that the other aircraft had been towed to the gate and lined up on the wrong parking line which put the aircraft 20 feet to the right of where it should have been parked; obviously infringing upon our Safety Zone. [I suggest that there are] wing walkers stationed at the end of the Safety Zone lines to clear the area before we enter into the parking area. Especially when the aircraft parked on either side is not a Company aircraft. We had a lot of people on the ramp to clear the Safety Zone. Poor communication between them contributed to the incident.


Second narrative: With four people outside the aircraft and a marshaller waving us in; we felt safe to proceed to the gate. After a short roll; our wing walker gave the X and we immediately stopped. This is when we became aware that our wingtip [had impacted] our neighbor's wingtip. Maintenance later told us that they felt the other aircraft we taxied into was parked on a wrong line causing their wingtip to be in our Safety Zone. My Captain was almost perfectly on the J-line when we impacted the other aircraft and only another five feet from our final parking spot.


Synopsis: B737-800 flight crew reported contacting another aircraft's wingtip while taxiing into the gate under ground personnel guidance.