Cargo and Baggage Loading: Floor Loads, Restraint and Distribution
Floor and running load limits
Each cargo hold has a floor load limit in kg/m² (or kg/ft²) and often a running load limit in kg per metre of floor length. A concentrated load must be spread over enough contact area and enough floor length to stay inside both. Point loads and the limits of ULDs or pallets apply on top of these figures. Load spreading uses spreader boards, pallets or double-deck loading; the contact area, not the outer size of the crate, is what counts.
Distribution and restraint
Load heavy items near the aircraft CG and spread mass between forward and aft holds to keep the CG inside the envelope throughout the flight, including after fuel burn. Cargo and baggage must be restrained to approved tie-down points or by an approved container/restraint system, designed for the certification loads (typically 9 g forward and 1.5 g aft and lateral for items in the fuselage). ULDs must be locked in place and their contours respected.
Dangerous goods
Dangerous goods must be checked against the loading chart for compatibility, segregation and quantity limits, loaded in the permitted position, and reported on the NOTOC to the commander. Some items require ventilation, separation from other goods, or are forbidden on passenger flights.
Worked example
Floor limit 732 kg/m², running limit 900 kg/m. A crate of 1 000 kg has a contact area of 0.72 m² and a length of 1.50 m. Area load = 1 000 / 0.72 = 1 389 kg/m², well above 732. Running load = 1 000 / 1.50 = 667 kg/m, below 900. The crate needs spreading to at least 1 000 / 732 = 1.37 m² of contact area, for example a spreader board of 1.5 m × 1.0 m, before it may be loaded.
Traps that cost marks
Using the pallet's outside dimensions as contact area; checking area load but not running load; ignoring the cumulative load where two heavy items sit close together; loading a heavy item in the aft hold without rechecking CG; and sending dangerous goods without a NOTOC or with incompatible goods adjacent.