Date: 201303
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Night
Aircraft: B767-300 and 300 ER
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Tower ZZZ
Aircraft component: APU
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Training / Qualification; Time Pressure; Distraction; Communication Breakdown; Workload
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Fuel Issue
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew FLC complied w / Automation / Advisory; Flight Crew Took Evasive Action
Contributing factors: Environment - Non Weather Related; Weather; Procedure; Human Factors
Primary problem: Human Factors

Narrative: We taxied out as a line of thunderstorms was passing the departure airport. During the starts and stops of the engines during the wait for takeoff on the west side; we were finally told to expect a departure to the southeast on the departure on the east side off 17. My First Officer suggested we keep the APU running as we continued over to the other side and I agreed; as we would need it for the final engine starts. Shortly thereafter; they changed us back to the west side again on 18. In the reset process for this; the APU shutdown got over looked and missed again after takeoff on the Cleanup Checklist. I was the flying pilot enroute and the running APU was discovered later in the flight. It helped explain at that point the possible reasons for having burned more fuel; amongst our reroute and weather deviations on the flight. We of course shut it down immediately and kept it off till after landing. I continued to adopt further step climbs when able as we continued uneventfully our foreign destination. We continued to save fuel and found that the extra burn did not impact our endurance and divert options in a significant fashion. I plan of course as the flying pilot to increase my checklist backup in the future; and improve my scan of the overhead panel to assist the pilot monitoring; so I can avoid these types of omissions going forward. Thanks for taking the report.


Second narrative: While waiting in the hold pad with our engines shutdown; we were told to start up and get ready to taxi to the east side of the airport for departure. There was a line of thunderstorms passing through; and a number of aircraft were holding for departure. After starting the engines I suggested to the Captain that we might leave the APU running because it looked as though we would be shutting down again on the other side of the airport. He agreed so we left it running. As we were getting ready to taxi; ground told us we were now going to depart from 18; and to contact Tower. Tower told us we were next after the aircraft taking the runway; I set the FMS up for an 18 departure again; and we completed the Mechanical Checklist. It was a little rushed; and none of us thought about shutting down the APU. It was bumpy on the departure; and we did some deviating due to the weather. We did not notice the APU running until about halfway into the flight; and then it was shutdown. More care should be taken when operations are abnormal due to weather; or whatever the cause; not to be rushed; and even to go a little slower than normal; just to look for this kind of thing.


Synopsis: An international B767 crew departed after multiple distractions caused by a weather related departure delay with engine shutdowns; then discovered after hours of flying that the APU had remained operating.