Why passenger flights carry freight below the cabin

A second network under the seats

The lower hold carries baggage, mail and freight in the space available on a passenger flight. Dedicated freighters provide another capacity source. The route and frequency of passenger services therefore also affect cargo connectivity.

IATA

Why the space is variable

Aircraft type, baggage demand, fuel load, distance and operating limits determine how much freight can be accepted. Published theoretical volume is not the same as executed capacity; IATA distinguishes available cargo space using flown-flight data.

IATA

What planners compare

Forwarders compare schedule, transfer time, handling requirements and reliable capacity rather than distance alone. Per-shipment emissions estimates also depend on aircraft and load assumptions, including how passenger and cargo activity are allocated.

The passenger timetable sets the cargo clock

Freight travelling below the cabin uses capacity on flights designed primarily around passenger demand. A shipment may need a road transfer, a hub connection and customs processing before it reaches the final airport. A convenient passenger nonstop is not automatically the fastest cargo journey if cut-off times or available hold space are poor.

A shipment’s shape can matter as much as its mass

Two shipments with the same weight can require different hold volume and loading arrangements. Door dimensions, packaging, unit-load-device compatibility and handling limits can prevent an item from using otherwise available capacity. Ask for confirmation for the actual aircraft and shipment, not just the model family. Cargo traffic in tonne-kilometres measures transport work, not whether one oversized piece will fit.