Weight and Balance
HB-IWF (the occurrence aircraft) was to be operated within the following weight limits:
Table: HB-IWF Weight Limits
The C of G limits given in the load index below are valid up to the maximum TOW with landing gear extended.
(See chart of "Actual loaded index ZFW - loaded index TOW.")
Lateral loading is restricted by a maximum unsymmetrical fuel load of 1 800 kg.
The MD-11 has five cargo compartments. The configuration used for SR 111 is Swissair unit load version 260, depicted below.
(See illustration of "MD-11 cargo compartments.")
Table: Cargo Compartments and Unit Load Version 260
Swissair defines the structure weight as the weight of the aircraft including furnishings and loose equipment.
Swissair defines the basic empty weight as the combined structure weight and standard fluid weights.
The basic empty weight for HB-IWF (the occurrence aircraft) was as follows:
Table: HB-IWF Empty Weight
Swissair's weight control system uses average basic weights for groups of the same aircraft type and configuration. HB-IWF was in the 131 925 kg basic weight group.
Swissair defines the dry operating weight as the basic weight plus operational items, including crew members, their baggage, and pantry items (e.g., galley, bar, food, and beverages). Swissair uses standard weights for crew members (90 kg each); the pantry weight is based on the style of pantry. SR 111 had 14 crew members and pantry code M.
The dry operating weight for HB-IWF was as follows:
Table: HB-IWF Dry Operating Weight
The following cargo weights and allocations for SR 111 were provided by Swissair and verified during the investigation based on collected waybills.
Table: SR 111 Cargo Weights and Allocations
(See illustration of "Passenger sections.")
The tables below detail the number of passengers assigned seats in each section, the distribution of passengers by gender and age, and standard passenger weights used in load calculations.
Table: Passenger Summary from Passenger Manifest
Table: Passenger Summary from Post-accident Review
Table: Swissair Standard Passenger Weights
Allied Fuels fuelled the aircraft with Jet-A fuel while it was parked at the gate at 2340. The total fuel weight was as follows:
Table: SR 111 Total Fuel Weight
The flight plan indicated that SR 111 would use 1 000 kg of fuel for taxi and 49 600 kg for the trip. The actual taxi fuel used, as recorded on the FDR, was 720 kg. The take-off fuel was estimated at 64 300 kg. The aircraft taxied with a total fuel load of 65 300 kg. A fuel density of 0.812 kg/L was used for SR 111 weight and balance calculations.
The information provided by Swissair indicated that the actual dry operating weight was 137 713 kg. The cargo weight was calculated by Swissair as 21 125 kg. Calculations performed during the investigation indicated that the total weight of the cargo, including passenger baggage as determined by waybills and standard weights, was 20 927 kg. While the 198 kg difference in cargo weight could not be resolved using the waybills provided, this difference represents less than 0.1% of the TOW. From an aircraft loading standpoint, this difference is negligible. Swissair calculated the passenger weight by multiplying the standard weight of 84 kg by the total number of passengers, excluding infants. Calculations performed during the investigation determined the following weights:
The load control computer calculated the estimated TOW of SR 111 to be 241 147 kg. A detailed calculation performed after the occurrence revealed that the actual TOW was 241 112 kg. The 35 kg difference is negligible. Both weights are within the maximum structural limits.
The load control computer calculated the C of G to be 19.8% MAC. Using the balance table, the C of G was manually calculated to be 20.0% MAC. Both of these figures are well within the balance limits.
(See copy of "Final load sheet.")
 Limitation to prevent flaps from being overstressed when selecting landing flaps in flight at weights in excess of normal landing weights.
 There is a difference between the Passenger Manifest and the Post-accident Review of the passengers by gender. This is attributed to the ticketing information. The passenger names were correct, but the gender was incorrect on the manifest. Gender information is used for weight calculations. Swissair used the same standard weight for males and females; therefore, the difference in the gender was inconsequential.
 There were two infants who were not ticketed or assigned a seat, but who were included in the load control.