Date: 201310
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Aircraft: MD-83
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: Confusion; Training / Qualification; Situational Awareness
Anomaly: Deviation / Discrepancy - Procedural Weight And Balance; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Dispatch; Person Gate Agent / CSR
When detected: Other Post Flight
Result: General None Reported / Taken
Contributing factors: Procedure; Manuals; Human Factors
Primary problem: Ambiguous

Narrative: Dispatcher was transferred a weight and balance call for the departing flight due to Customer Ops not being able to get numbers without exceeding aircraft MZFW. Dispatch spoke with the Captain and ran the same numbers given Customer Ops and reached the same conclusion. After reviewing the charter trip sheets there were 104 checked bags that had not been accounted for that were now present in the aft hold of the plane. Based on wording in the average weight worksheet of the charter trip sheet; it appeared that the checked bag weight was being included in the average passenger weight. After re-confirming the bag count and alleged average checked bag weight with the charter services rep; the Captain advised Dispatch of an average weight of 16 lbs per checked bag and since the weight and balance system counts checked bags at 30 lbs; 16 lbs was removed from the average passenger weight to compensate.   Further review of the numbers after the flight reveled that the 104 checked bags had never been accounted for in the trip sheet and the Captain should not have removed the 16 lbs from the passenger weight. Because of the 104 checked bags and 16 lbs per passenger; the aircraft departed roughly 3000 lbs heavier than the weight and balance numbers showed.   Other contributing factors:  - The release sent to the crew had been planed with standard passenger weights of 190 lbs/passenger which were 37 lbs under the actual average passenger weights.  - The 104 checked bags had never been accounted for on the charter trip sheet   - The Dispatcher conducting the weight and balance was not aware the GOM requires 16 extra pounds be added for charter passenger.   Charter passenger average weight on this flight was 211 lbs plus 16 lbs for a total of 227lbs/person. The charter department needs to prepare better trip sheets that include checked bags and if a charter services rep is traveling with the flight confirm the actual checked bags to dispatch/Customer Ops before weight and balance is computed.  Dispatchers and crew members need to be aware of the requirement for an additional 16 lbs per charter passenger weight and not alter the weight in W&B.  Dispatcher needs to be cognizant and plan releases with the weights from the charter trip sheets for groups that are non-standard weight.




Synopsis: MD-83 Dispatcher describes a charter flight with a passenger load that exceeds the MZFW. Assumptions are made that allow the flight to depart. Post flight research reveals that the weight and balance was not properly calculated.