MD-80 Series (DC-9-80) Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Distraction; Training / Qualification; Workload; Confusion
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Weight And Balance; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
General None Reported / Taken
Chart Or Publication; Company Policy; Procedure; Aircraft
Aircraft arrived at XA:51; and was scheduled to depart at XC:15. The left fuel quantity indicating system was placarded under MEL 28-4b. This required an alternate fueling procedure. I had expected that either the fuel quantity would be verified with the dripless measuring sticks or by means of an alternate fueling procedure. Shortly after we started boarding; I was informed by maintenance that we would have to stop boarding and deplane in order for them to complete the alternate fueling procedure. There is nothing in the MEL that provides any warning of this; nor is there any description of the alternate fueling procedure.Following deplaning; it appeared to me that the fueling process was to de-fuel the left main; add fuel to the right main; transfer that known quantity into the left main; then re-fuel the right main.During the fueling process; the maintenance and fueling staff appeared to have a target fuel quantity of about 8500 pounds for each main tank. At one point; the mechanic in the cockpit asked if it would be a problem to have a hundred extra pounds in the left main; I said it would not. As I did not know the fuel density nor the procedural requirements they were dealing with; I did not give this much thought. I should have.Once this was complete; we re-boarded the passengers. The first officer questioned the main tank quantities (the deferral had to do with intermittent dashes appearing in the fuel quantity indication display). Both read between 8500 and 8600 pounds; with about 6300 in the center.  I said it probably had something to do with the alternate procedure. However; I looked up the limitation; noted that we would have to adjust the zero fuel weight; and attempted to call the load planner.There was no answer at the load planning number that I had. Since the crew departure information sheet only lists the last 4 digits of the number; I may have used the incorrect prefixes. In any event; I then called the dispatcher and advised him. I read off the gauge readings to him (knowing the fault with the left gauge; and noting that it matched the right; I believed it to be correct...we had not received the fuel slip yet). The dispatcher said he would contact the load planner.Now; the planned zero fuel weight was 115;600 lbs. With 6300 in the center tank; this would have been fine. I'd like to say that's what I was thinking; but actually I had overlooked the whole issue. There was quite a bit going on during the boarding and departure prep; and the best I can say is that in my mind; I had consigned the situation to one identical to tow fuel. Of course; it was identical to tow fuel...but in those cases; the load planner has already adjusted the zero fuel weight and the cockpit crew never really encounters a problem.We got the fuel slip. My principal concern was to make sure they had added the correct total fuel; and then rely on the center and right quantity indications to assure me that the remainder was in the left tank. Because I was not familiar with the exact procedure that maintenance had used; this was slightly uncomfortable amidst everything else that was going on. However; the total add was correct; the add difference well within margins; and the gauges matched what I saw on the after fueling entries.Later in the flight; I noticed that this fuel slip has a gate release quantity shown for each tank. This is printed in rather faded ink; and I did not even see it when we first got the fuel slip. I was under the impression; based on the discussion between the mechanic in the cockpit and those on the ground; that 8500 pounds in the mains was what their procedure required. Had I seen the 9345 pounds in the gate release column; I might have questioned the distribution again.Now the agent asks if we are ready to close; and I ask how many souls on board. She is a bit flustered and starts to add up first class; coach and crew. This is pretty typical; about half of the gate agents I encounter do not yet understand the concept of souls on board. I specifically ask if there are any lap children; she says no. So I note 145 souls on board.We start up and taxi out. The closeout arrives; and it says there are 146 souls on board; including one child. For context; this takes place while we are starting the taxi with the ground controller reading off several taxi clearances at once and at least half of the recipients not moving or even understanding what was said. As we taxi around the bend for departure; we get another note that our closeout has been cancelled. We are now number one; but the tower is launching several aircraft from the full length position. We are trying to figure out where we can go in anticipation of the instructions we will get when we tell the tower we are not ready. Then the tower decides to change the plan and taxis us all the way down to the full length departure. This bought us some time; and I told the FO to call load on the radio and see what was up. Before he does that; we get another message from dispatch saying we are 50 pounds over the max zero fuel weight.We told the tower we needed a few minutes; and taxied around the pad into a position opposite the full length position for 28R. We contacted the dispatcher; and he requested a child count. I asked the flight attendants to do so; and they replied that we had one child. It turned out that we had at least two; based on who I saw during deplaning. We arrived at a total weight that had us below the max zero fuel weight; the closeout was sent; and we departed. The difference between the zero fuel weight on the TPS and the actual zero fuel weight was about a 400 pound increase. We did not have that information until we had moved the airplane. Indeed; the first closeout came through with the increased zero fuel weight and no problem associated with it. It was only after the initial closeout arrived that we were advised of the problem.However; my error was in not seeing the potential for that possibility. What I should have done was not move the airplane off the gate until I got a closeout; and then done the math myself. Had I focused on how close we were to the max zero fuel weight with the center tank fuel included; I might have questioned the original closeout; before moving the airplane. However; I was more focused on trying to be sure the fueling had been done correctly.The bottom line is that we probably taxied the airplane between 50 and 100 pounds over the max zero fuel weight. I was advised later by maintenance that no inspection was required for that event.What could improve this? It would be quite helpful if I knew what the alternate fueling procedure was and what requirements were associated with it. l have been doing this for quite a few years and I know something about alternate fueling procedures; but not precisely what needs to be done in this situation; or what is in the AA fueling manual. As I was very involved in the investigation of fuel tank safety; I am aware of the problems with static discharge particularly during cross-tank fueling and de-fueling; so not boarding the pax makes sense; but again; with no idea what maintenance is actually going to do; I was not able to ensure that everyone was communicating.I do not know where the planned fuel load that maintenance used came from; but it did not match the auto generated distribution on the fuel slip. Without the density beforehand; there is no real precise way for the cockpit crew to anticipate that; and main quantities as low as 8700 pounds are acceptable without a zero fuel weight penalty. Had we had a target fuel distribution ahead of time; we might have asked more questions as well. Accurate pax counts and a clear understanding of the concept of souls on board would help as well. We probably see inconsistencies between the closeout and the SOB reported by the agent about 50% of the time.At the end of the day; the dispatcher; FO and myself were trying to get this right; but we stumbled; myself particularly for not grasping the potential problem. It is a pretty small problem in this instance; the potential for larger error seems enormous to me; so it bears consideration.
A MD-80 fuel quantity gauge MEL 28-4B required a complex alternative fueling procedure which the crew; Dispatch; and Maintenance became confused about. The aircraft pushed and taxied from the gate over max zero fuel weight by a small amount.