Date: 201606
Local time of day: 0001-0600
Location: ZZZZ.Airport, US
Light: Night
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Dispatcher
Reporter qualification: Dispatch Dispatcher
Human factors: Workload
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Weight And Balance
Detector: Person Ground Personnel
When detected: Aircraft In Service At Gate
Result: General Flight Cancelled / Delayed
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: I have worked this flight many times. It is not deemed by Management a 'critical flight'; but it is very time consuming to plan; communicate; and monitor this flight. This flight often carries heavy loads of tuna in boxes. Many times the pits are staged very close to their limits. Some days there was no tuna caught; so the loads won't be heavy. Today this flight was quite heavy with tuna. There were also 23 through bags. The station communicated very early with me how they would like the tuna loaded; as well as asking for 'max bag' limits for each pit. This is the best practice for this flight to ensure that the pit limits (structural limits) aren't exceeded. I saved their message and would get back to it when it was time to plan the flight.My workload was rather high today. In fact; after XA:00 my tab was nonstop. At all times there was at least one 'locked' flight that needed to be worked. Usually; there were several. I also had flights that were weight restricted; as many as three on my screen at once during this time. I was doing my best to keep up; but it was challenging. Shortly after this flight 'locked'; fuel was added; and I was able to start planning. It took me quite a while to plan the flight; with many interruptions from working other 'locked' flights; following up on weight restrictions; and dealing with a large number of phone calls related to the weight restrictions; issues with live animals; and requests to unlock flights. I was able to pit the tuna and other cargo in a way that would balance the aircraft. Then; I added the bags to each pit. I took pit limit for each pit; subtracted the cargo items; and divided by 36; the [flight] standard bag weight. This would give me a max bag number for each pit. I allowed a little extra to account for heavy bags. In my haste to work my busy screen; I probably didn't allow enough extra weight in each pit for the heavy bags. This flight normally has a few heavy bags; not as many as some other markets in the region. I made the flight ready and returned to my other flights. Shortly after I readied the flight; we had the shift change. The flights being worked tend to shuffle around a bit during this time. As often happens; I ended up with several locked flights during the change; which meant I stayed continuously busy without much chance to review the readied flights I had worked; including this one. I didn't notice any big changes when the flight went to 'closed' status; so I just continued trying to keep up with my tab.At scheduled departure time; I got a call from the station. They were having difficulty closing out the flight; getting a response of being over pit weight. I attempt to review the flight. I get a series of popups advising 'pit weight exceeded'. Once I cleared the popups; I saw a blank screen. If I squinted; at the very bottom of the screen; the available pit weights were dimly visible. I saw pit 3 showed '-17'; so I imagine that pit 3 must be over the pit limit by 17 pounds. I reviewed the bag counts with the ops agent; and determined that pit 3 was indeed overweight by 17 pounds. The flight had already pushed; and I could hear the crew over the Ops radio. I could hear the pilots offer to move passengers; thinking we were out of balance. I explained to the Ops agent that we were over the pit limits; and moving pax would not help. I advised we would have to move 2 bags to pit 2 to correct the problem. The crew wasn't happy as they would have to shut down an engine and miss their departure slot. While all of this was going on; my screen was just as busy as it had been since XA:00. Multiple locked flights; including an overstaged domestic wide body that has a short locked time relative to  most wide bodies; plus a couple of weight restrictions and phone calls mixed in. My error was in not allowing enough extra pit weight to account for heavy bags. This particular flight required high quality work from its Load Planner. I wasn't able to provide enoughattention to this flight given all that was expected of me during this time period.




Synopsis: Air carrier Dispatcher reported making an error in load planning procedures that caused a delay; citing workload issues as contributing.