Narrative:

Our original flight plan showed estimated fuel on board (efob)/remaining fuel on board (remf) to be 5.4. This was a little low; but the weather [at the destination airport] was excellent and there were plenty of runway options. I accepted the flight plan with only minor concern based on weather/numerous options. The fueler over fueled by 300 lbs; so I felt better with 5.7 efob.prior to pushback; the APU would not start and maintenance was contacted. After some troubleshooting; they deferred the APU.we started one engine at the gate with external air/power and pushed back. Needing a 5 minute warmup for the first flight of the day; and due to the uphill taxi to [the runway]; we immediately started the second engine.on the taxi out; we were told to contact clearance delivery for a full re-route. Once received; we passed on the new route to dispatch; and waited for a new flight plan. Efob/remf on the new flight plan was 5.3. (I thought this was only 100 lbs more than the original and still not a major problem......however; I was wrong...... The new flight plan was taking into consideration the extra 300 lbs the fueler put on; so the new route was actually 400lbs more than the first. If I had realized this at the time; we would have gone back to the gate for more fuel.) once we received the new flight plan started the taxi; we got a comm ECAM. I contacted [maintenance] and we resolved the problem expeditiously; but the engines were still running due to the uphill taxi to [the runway]. Pushback to takeoff ended up being 45 minutes. This was unexpected and we had anticipated a much shorter taxi. Shutting off two engines was not an option due to the inoperative APU. Shutting one down was not an option due to the uphill taxi. The reroute and ECAM were unexpected and obviously not planned for. Every decision made was trying to be safe; legal; and expeditious.I was constantly watching the fuel and we had 2000 lbs above min fuel required for takeoff roll when we were given takeoff clearance. I decided there were many places we could go between [our location] and ZZZ if we needed to stop short; and elected to continue.on climbout; we were able to climb to FL370 right away and efob on the ACARS said we would land with 6.0. This made us feel much better; but the howgozit said efob of 5.2.as we monitored the fuel; we did see the efob start to decline towards an efob of 5.2 and we contacted dispatch. She acknowledged that she was showing that we would land with 5.2; but soon after that; our efob was declined to 4.9.......our concern was heightened.we were discussing possible options. We asked if there were viable options closer to ZZZ in case some reroutes were able to help. Alternate ZZZ1 and alternate ZZZ2 were not good due to traffic in ZZZ1 and windshear in ZZZ2; but ZZZ3 was a good option.as we continued; we requested directs that increased our tailwind; and declined those that did not. We stayed in touch with dispatch and asked if there were any route changes she could recommend based on winds. She said we were on our best route.as we passed abeam ZZZ1; dispatch said [they] had talked with ATC and that there were no delays; weather was good; and they were aware of our situation. No holding was planned; and if holding/delays arose; we would be exempt.as we approached ZZZ3 efob on the ACARS was saying 4.5. No one liked this situation; but based on current status of ZZZ and their knowledge of our fuel state; we felt it was safe to continue.current efob was 4.5Min fuel (45min) was 3.2Emergency fuel was 2.2We asked ATC for the most flexibility they could give us in the descent; as we were behind on fuel. They did accommodate us some; but since I had not declared min fuel; there were some vectors for spacing. When we got with approach; I asked our sequence for fuel planning purposes; and was told number 12. We were not min fuel and even though they had been alerted to our fuel state;so they did not seem to be giving us any priority.the pattern; while long due to numerous aircraft; was probably normal for ZZZ. Weather was excellent. I told the copilot that if ATC discussed/directed a go-around for us and we would land.after the long pattern setting us up for [the runway]; we finally landed and touched down with 3.5. Taxing to the gate; we had to wait for external power due to the inoperative APU and in report was 3.1.

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Original NASA ASRS Text

Title: Air Carrier Captain reported a higher than expected fuel burn due to an APU malfunction and a reroute after pushback.

Narrative: Our original flight plan showed Estimated Fuel on Board (EFOB)/Remaining Fuel on Board (REMF) to be 5.4. This was a little low; but the weather [at the destination airport] was excellent and there were plenty of runway options. I accepted the flight plan with only minor concern based on weather/numerous options. The fueler over fueled by 300 lbs; so I felt better with 5.7 EFOB.Prior to pushback; the APU would not start and maintenance was contacted. After some troubleshooting; they deferred the APU.We started one engine at the gate with external air/power and pushed back. Needing a 5 minute warmup for the first flight of the day; and due to the uphill taxi to [the runway]; we immediately started the second engine.On the taxi out; we were told to contact Clearance Delivery for a full re-route. Once received; we passed on the new route to dispatch; and waited for a new flight plan. EFOB/REMF on the new flight plan was 5.3. (I thought this was only 100 lbs more than the original and still not a major problem......however; I was wrong...... the new flight plan was taking into consideration the extra 300 lbs the fueler put on; so the new route was actually 400lbs more than the first. If I had realized this at the time; we would have gone back to the gate for more fuel.) Once we received the new flight plan started the taxi; we got a COMM ECAM. I contacted [maintenance] and we resolved the problem expeditiously; but the engines were still running due to the uphill taxi to [the runway]. Pushback to takeoff ended up being 45 minutes. This was unexpected and we had anticipated a much shorter taxi. Shutting off two engines was not an option due to the inoperative APU. Shutting one down was not an option due to the uphill taxi. The reroute and ECAM were unexpected and obviously not planned for. Every decision made was trying to be safe; legal; and expeditious.I was constantly watching the fuel and we had 2000 lbs above min fuel required for takeoff roll when we were given takeoff clearance. I decided there were many places we could go between [our location] and ZZZ if we needed to stop short; and elected to continue.On climbout; we were able to climb to FL370 right away and EFOB on the ACARS said we would land with 6.0. This made us feel much better; but the HOWGOZIT said EFOB of 5.2.As we monitored the fuel; we did see the EFOB start to decline towards an EFOB of 5.2 and we contacted dispatch. She acknowledged that she was showing that we would land with 5.2; but soon after that; our EFOB was declined to 4.9.......our concern was heightened.We were discussing possible options. We asked if there were viable options closer to ZZZ in case some reroutes were able to help. Alternate ZZZ1 and Alternate ZZZ2 were not good due to traffic in ZZZ1 and windshear in ZZZ2; but ZZZ3 was a good option.As we continued; we requested directs that increased our tailwind; and declined those that did not. We stayed in touch with dispatch and asked if there were any route changes she could recommend based on winds. She said we were on our best route.As we passed abeam ZZZ1; dispatch said [they] had talked with ATC and that there were no delays; weather was good; and they were aware of our situation. No holding was planned; and if holding/delays arose; we would be exempt.As we approached ZZZ3 EFOB on the ACARS was saying 4.5. No one liked this situation; but based on current status of ZZZ and their knowledge of our fuel state; we felt it was safe to continue.Current EFOB was 4.5Min Fuel (45min) was 3.2Emergency fuel was 2.2We asked ATC for the most flexibility they could give us in the descent; as we were behind on fuel. They did accommodate us some; but since I had not declared min fuel; there were some vectors for spacing. When we got with approach; I asked our sequence for fuel planning purposes; and was told number 12. We were not min fuel and even though they had been alerted to our fuel state;so they did not seem to be giving us any priority.The pattern; while long due to numerous aircraft; was probably normal for ZZZ. Weather was excellent. I told the copilot that if ATC discussed/directed a go-around for us and we would land.After the long pattern setting us up for [the runway]; we finally landed and touched down with 3.5. Taxing to the gate; we had to wait for external power due to the inoperative APU and in report was 3.1.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.