Date: 201605
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: B737-700
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: Turbine Engine
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Confusion; Distraction; Situational Awareness; Workload
Second reporter function: First Officer
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown
Detector: Person Ground Personnel
When detected: Aircraft In Service At Gate
Result: Flight Crew FLC complied w / Automation / Advisory; Flight Crew Took Evasive Action
Contributing factors: Human Factors; Company Policy; Procedure
Primary problem: Human Factors

Narrative: Last leg flown to completion. Taxi in to the gate included three minute time clock for number two engine shutdown. Arrived at Gate XXX Safety Zone. Upon turning into the Safety Zone; we had to stop briefly for equipment to be moved. After movement we proceeded into gate safely. Parking brake set; number one engine shut down; Ground Personnel cleared into zone; and Parking Checklist was started. During checklist; the Ground Crew asked if we were receiving ground power. Checklist was fragmented as a result. Ground power was established and APU was shut down. I got out of the seat and began final shutdown procedures. Time elapsed was approximately three minutes. F/O remained seated and was completing post flight duties. My attention was raised by a flashing light from down on the ground. Maintenance and Ramp Personnel alerted us to the fact the number two engine was still running. We immediately shut it down. Maintenance Personnel boarded the flight deck and were quite emotional about the event. Discussion ensued and an attempt at an explanation was given. Conversation was very brief. Normal hand off to Maintenance Personnel then completed.First; the distraction in the Safety Zone prevented number two shut down. Second; ground power discussion prevented full completion of Shutdown Checklist which would have caught the running engine. Noise in the cockpit did not alert us. The correction? Just have to maintain the ultimate concentration anytime we are in the Safety Zone. Checklist completion is of the utmost importance. I failed as a Pilot in Command; we failed as a Crew and it was a huge learning lesson all around.


Second narrative: I was the First Officer on the flight. We arrived on a late evening flight. As we taxied to the gate; I thought the Captain had shut down the number two engine. I'm not sure if I thought I heard the engine spool down; or if I thought I saw his hand on the fuel cutoff switch. Either way; I thought the engine was shut down as we approached the taxi in line. We came to a stop at the gate; the Captain set the parking brake; shutdown engine number one; and gave the clear signal to the ramp. As he gave the clear signal; I turned off the beacon; and continued my flow. The Captain called for the Parking Checklist. I began to read the checklist; but I did not verify switch position as I read it. As I read the checklist; a Ramp Agent was knocking on the nose of the aircraft. I believed that he was verifying external power was connected. I looked up to verify if it was; it was not connected. I looked back at the checklist to continue; and the Ramp Agent knocked on the nose again. I looked down; gave him the thumbs down; to indicate we have no external. I was not aware of what the Ramp Agent was trying to tell us; that the engine was running. The external power was then connected; and we completed the Parking Checklist; but with the distraction; I believe that is why I missed the switch verification as I read it. Once the checklist was complete; the Captain got out of his seat and was standing in the flight deck. The Ramp Agent knocked again; and was pointing towards the back of the aircraft. Also; another Ramp Agent; or perhaps a Mechanic that was on the ground; shined a flashlight into the flightdeck. The Captain opened his window and whoever shined the flashlight said the engine was still running. The Captain immediately shut down the number two engine; and we reran the Parking Checklist.Be sure to verbalize an engine shutdown so both Pilots are aware; just in case it is missed somehow. Perhaps have the Captain call for an engine to be shut down; and have the First Officer shut it down; so both Pilots are involved. Be sure that the Ramp and Pilots are aware of proper signals so the communication is clear if only hand signals are used. I know I will be reviewing the signals to be sure I know them; to help prevent this again.


Synopsis: A B737-700 flight crew taxied into the gate; shutdown #1 engine; but mistakenly failed to shut down the #2 engine. The Captain finally shutdown the engine after ramp agents notified the crew twice about the problem which the crew misunderstood as a request to confirm ground power ON.