Date: 201307
Local time of day: 1801-2400
Location: MSY.Airport, LA
Flight conditions: VMC
Light: Daylight
Aircraft: A319
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Tower MSY
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Object
Detector: Person Ground Personnel
When detected: Taxi
Result: Aircraft Aircraft Damaged
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: As I was taxiing into the gate at MSY; I noticed a portable air stair vehicle parked in the vicinity of the left safe area.  There are no painted safe area lines at this gate; only a yellow lead-in line to the stopping point.  There was a wing walker adjacent to the stairs and he had his lighted wand up signaling the wing would clear the stairs. As I approached the Marshaller; he began doing what appeared to be a sort-of dancing motion on the yellow line for about 5 seconds.  This was a slight distraction as I approached the gate; and I am not sure how close to the stairs the wing was at that time; I think the dance move was early on in the marshalling process.  My focus was staying on the line and following the Marshaller's directions.  At no time was there any attempt by ground personnel to stop the aircraft as it approached the stairs.  I never felt any yaw or bump as the wing made contact with the stairs.  First Officer said he may have felt a slight bump.  First Officer went outside to perform the post flight walkaround approximately 7-8 minutes after the Shutdown Checklist. During this time; no one from the ramp came to the cockpit to inform the crew that we had hit the stairs.  Outside; First Officer noticed the stairs very close to the wing and asked the wing walker if we had hit it and he said yes.  First Officer asked him why he didn't signal the Marshaller or the Captain of imminent contact and he stated he was not trained to do that; only to stand and look up at the wing and hold his wand up.  First Officer returned to the cockpit to tell me of the events.  I went down and had the same conversation with the wing walker.  It is not inconceivable that had First Officer not gone out to do the Post Flight Walkaround; we would have never known of the incident.  First Officer and I both looked at the wingtip and only saw some paint damage to the winglet on the underside. A maintenance write up was placed in the FDML.  The ramp personnel are contracted in MSY; they are not [Company] employees.


Second narrative: In my opinion; this event might have been prevented had there been safety area boundary painted on the ground. This would have triggered the Captain and myself that the air stairs were too close. We would have come to a stop and waited for the air stairs to be moved; or at least questioned the ramp personnel about the stairs before proceeding. Since these were not available; we believed that the ramp crew had the best vantage point of the aircraft from their position. Therefore we depended on their experience and training to assist us in making sure our aircraft was free from the obstruction. Why the Wing Walker on the left side knew the aircraft was going to make contact with the stairs and did nothing at all to prevent it; I cannot say.


Synopsis: A319 flight crew reported their wingtip contacted the air stairs while under Marshaller guidance taxiing in to a gate in MSY.