Date: 201501
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Aircraft: MD-82
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Other / Unknown; Situational Awareness
Second reporter function: First Officer
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Gate Agent / CSR
When detected: Aircraft In Service At Gate
Result: Flight Crew Became Reoriented; Flight Crew Returned To Gate
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: Landing uneventful; we were given an expedited crossing of the departure runway. We accomplished the after landing checklist but; due to the expedited crossing; I wasn't sure if the First Officer (FO) started the APU (which had been consistent/standard practice so far in the trip). We were cleared to enter the ramp and I consciously elected to leave both engines running (which was contrary to my standard practice during the trip). As we turned to pull into the gate; a white; unmarked van cut across our path. We saw him coming so no immediate stop was necessary but we both remarked about the various fueling and vendor traffic driving habits causing a conflict with aircraft. We pulled to a stop normally; parked the brakes and I believe I commanded 'shut down engines'. The FO believes he heard 'shut down the left engine' (which had been the standard command throughout the trip). He shut down the left engine. The right engine continued to run and we finished the parking checklist and departed the cockpit.Minutes later (approximately three--the running engine burned 155 lbs of fuel since the counter had been reset at left engine shutdown) I received a page as I left the gate area requesting I return to the gate. I returned to find the right engine running. I immediately shut off the fuel lever. No damage or injuries occurred. The aircraft was chocked and the brakes parked. In my estimation; there are three distinct contributing factors in this event.1.) Complacency when reading the checklist. I assumed items had been accomplished; therefore; I felt no need to follow up the response with a tactile and visual check.2.) Complacency when relying on past actions as a predictor of future actions. We had done things the same way each leg; therefore; we would continue to do them the same way on every leg. 3.) Distractions. The expedited crossing to the ramp side of the runway; compressed time frame for completing the after landing checklists and vehicular traffic all led to this event. We are frequently admonished to be aware of all of these issues yet they still keep happening. Strict--unyielding adherence to policy and procedures is a must. No one is perfect and that is why policies and procedures exist. An event like this WILL happen if you allow yourself to become too comfortable.


Second narrative: Arrived at the gate and the parking brake was parked. The Captain remarked 'shut down the #1 engine; parking check list' I read the check list as the Captain responded. At the end of the check list I exited the aircraft. I needed to mail some bills I had paid during the layover the night before and I also needed to get something to eat. I had walked about 10 gates down from the aircraft and ordered some food when I heard an announcement asking the fight crew inbound from our flight please return to the gate. I thought that the Captain was most likely still there so I waited on my order and walked back. No one was there when I returned so I waited. About 5 min's later the agent walked up and I asked why she had called. She told me that one of the engines had been left running. She let me on the jet bridge and the Captain was walking off the Aircraft. He had only walked one gate over when he heard the announcement. He returned to the aircraft and shut it down.I believe this problem came about because of a pattern we developed during all our flights. After landing I started the APU shortly after landing. After about 2-3mins; allowing the engines to cool I would shut down the #2 engine at the Captain's request. We did this every flight. After landing on this flight it got very busy. We were clear to cross immediately after landing. I was still cleaning up the aircraft while getting the radio work covered with ground and ramp. When we parked at the gate and the Captain called for me to shut down the #1 engine; I didn't think about the #2 engine still running. We had always shut it down before. I believe the Captain thought the same. I read the check list and listened to the Captains responses. I should have been double checking him myself; but I didn't. I also should not have delayed doing my walk around. I needed to get my bills in the mail and the Captain had told me he could do the walk around if I wanted but I said no that I would do it when I returned. This has never happened to me and I have 28 years of flying commercial aircraft. I don't know what to say about it. I'm embarrassed that it happened to me. I'm just grateful that no one was hurt or that something more had come of it.


Synopsis: MD82 flight crew describes the circumstances leading up to both crew members leaving the aircraft parked at the gate with the right engine still running.