Two jobs on one airfield
Most airports were designed primarily for passengers, yet many also move a meaningful amount of freight. Cargo shares the same runways, taxiways and air traffic control as passenger flights, but it usually has its own buildings, trucks and staff. Understanding the split helps explain why some airports are known as freight centers and others handle cargo only as a side activity.
Two ways cargo flies
Air cargo travels in two main ways.
- Belly cargo rides in the lower hold of passenger aircraft, alongside baggage. It is a by-product of the passenger schedule, so it follows the routes and times passengers want.
- Freighter aircraft carry only cargo. Operators can choose routes and timing around freight demand, and the aircraft can usually carry larger or bulkier items through large doors or nose openings.
Which one is used for a given shipment depends on the size of the item, the destination and the schedule. A small box between two big passenger cities may go in a belly hold, while heavy machinery parts or a large consignment may need a freighter. Air freight as a whole is a broad topic, so the focus here stays on the airport side.
What a cargo terminal does
Freight does not go from truck to aircraft directly. It passes through a cargo terminal, usually located on the airport grounds or just outside it. The usual steps are:
- Freight arrives by truck and is checked in against its paperwork.
- It is weighed and measured, since both weight and volume affect how a shipment fits on an aircraft.
- Security screening takes place according to local rules.
- Pieces are consolidated onto pallets or into containers made to fit the aircraft’s hold, known as unit load devices.
- Built-up loads are moved to the aircraft by tugs and dollies.
Arriving cargo reverses the process: unloading, breaking down pallets, customs checks, and release to the receiver, or to one of the freight forwarders involved, for onward trucking. Customs clearance can happen inside the terminal or at a nearby facility, depending on the country and the type of goods.
Ground handling
Ground handlers are the companies or teams who load and unload aircraft, operate the ramp equipment and manage the movement between the terminal and the plane. Their work is tightly timed. An aircraft that sits idle on the ground is not earning revenue, so turnaround times are short, and a delay in the cargo terminal can mean freight misses its flight and waits for the next one.
Weight and balance planning is a particular concern. The position and weight of every pallet affect how the aircraft flies, so loading is planned and checked rather than done on the fly.
Hubs and spokes
A cargo hub is an airport where many flights converge so that freight can be sorted and sent onward. Rather than flying every origin directly to every destination, operators route shipments into a central point, sort them, and send them out on connecting flights. This is the hub-and-spoke model, and it works because it reduces the number of routes needed to connect many places.
Integrated express carriers often run sorting operations at night, so that parcels collected during the day can be flown to the hub, sorted and flown out before morning. Sorting centers at such hubs can be very large and highly automated, although the degree of automation varies. The aircraft are only one leg of the parcel networks that feed these hubs, which also rely on local vans and depots.
Hubs tend to develop where several things come together: a good geographic position, enough runway and apron space, reliable weather, available labor, and access to highways. Airports with restrictions on night flights may struggle to serve as express hubs, because night operations are so central to that business model.
What limits airport freight
Several practical constraints shape how much an airport can handle:
- Runway and apron space. Parking spots for large aircraft are limited, and cargo aircraft compete with passenger flights for slots at busy airports.
- Terminal capacity. Cargo buildings can become congested when volumes spike, for example during peak season.
- Curfews and noise rules. Many airports near residential areas limit operations at night.
- Road access. If trucks cannot reach the cargo area easily, freight can wait outside the terminal.
- Dangerous goods. Items such as batteries or chemicals require careful handling and documentation, and some are restricted on passenger flights. Hazardous materials rules apply to air freight just as to other modes.
Why freight goes by air
Air freight is typically used for goods where speed matters more than cost: urgent spare parts, high-value items, and goods that spoil quickly. Pharmaceutical logistics frequently uses air cargo for temperature-sensitive products, as do some producers of fresh flowers or seafood. Because it is usually more expensive per kilogram than other options, choosing it is often a trade-off, and the usual approach to mode selection weighs cost against speed and reliability.
The airport as part of a chain
An air cargo hub is rarely the start or end of a shipment. A package typically moves by truck to the airport, by air to another airport, and by truck again to its destination. Delays at any of those points can add up, and the airport sits in the middle where a lot of coordination has to happen. That is why the quality of road links, terminal procedures and customs processes often matters as much as the aircraft itself.