Date: 201702
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Ground ZZZ
Second aircraft: B737-800
Aircraft component: Wingtip
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Communication Breakdown
Second reporter function: Pilot Flying; Captain
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Aircraft
Detector: Person Flight Crew
When detected: Taxi
Result: Aircraft Aircraft Damaged; Flight Crew Returned To Gate; General Flight Cancelled / Delayed
Contributing factors: Airport; Procedure; Human Factors
Primary problem: Human Factors

Narrative: Cockpit preparation and boarding proceeded normally prior to this event. Upon completing the Before Start Checklist (above and below the line); and verifying that both pushback and cabin crew were ready for push; I called ZZZ ground and requested pushback from [the] gate. Ground cleared us to push with 'reference Aircraft Y off your right.' I looked out my right window (towards the right #2 wing) and spotted a 737 taxiing from West to East on taxiway Charlie. I noted no other aircraft behind [it]. I forwarded the ground clearance instructions to [the] Captain; who then relayed our clearance to the pushback crew. The push commenced and shortly after we were cleared to start engine one. Captain instructed me to start engine one and I began that procedure. Near the end of the engine start cycle; as we were parallel with taxiway Charlie (nose facing East); a very noticeable impact was felt and heard. The ground crew stopped our aircraft immediately; and shortly thereafter I could see a 737 parallel with us on taxiway Charlie stopped at our 10-11 O'clock position. It was immediately evident that the top of the winglet from Aircraft Y was missing; and with confirmation from the pushback crew; we were aware that some portion of our left wing impacted Aircraft Y. We shut down engine one immediately and remained on APU power. Aircraft Y was the first to notify ground control of the impact. Both aircraft remained stationary while airport operations vehicles and the fire department arrived on scene to document the incident. Initially no fuel leaks were reported. After several minutes while waiting for the investigation to complete; we were informed by the pushback crew that there was a fuel leak under the left wing. We deplaned the aircraft shortly thereafter from the 1R door using air stairs and shut the aircraft down. No injuries were reported from passengers or cabin crew at this time. The leak was later identified as a fuel drip from the #1 engine drain mast by a mechanic and was not associated (as far as we could tell and in the opinion of the mechanic) with the impact. Once Aircraft Y was towed away; [the] Captain and I re-powered the aircraft and occupied our duty stations while the aircraft was towed to a remote pad. Under guidance from the mechanic on scene; we started engine #1 for several minutes to stop the fuel leaking from the drain mast. After this successful procedure; [the] Captain made a logbook entry and we left the aircraft powered up and in care of the mechanic.The exact cause of this incident is unclear to me at this point; therefore it is hard for me to speculate on prevention.


Second narrative: [Report narrative contained no additional information.]


Synopsis: The flight crews of an Airbus A320 and a Boeing 737 each reported that their wingtips collided on the ramp during night operations.