Cargo & Air Freight Basics

Why Cargo Flies at All

Moving a shipping container by ocean freighter costs a fraction of what the same weight costs by air. Given that, it might seem strange that any cargo flies at all. The answer is speed, not price. Air freight gets chosen when time matters more than the extra cost — a document that has to reach another continent overnight, a machine part that is holding up a factory line, fresh flowers that will wilt in a ship's hold, or a vaccine that spoils outside a narrow temperature range.

The trade-off is straightforward. Ocean freight might take three to six weeks at very little cost per kilogram; road and rail cover regional distances at moderate speed and cost. Air freight moves the same shipment in a day or two, but at many times the price. Shippers pick air only for the slice of goods where that speed premium is worth paying — commonly estimated at well under one percent of world trade by weight, but a much larger share by value, since the goods that fly tend to be light, urgent, or expensive.

Belly Cargo vs. Dedicated Freighters

Most air cargo does not travel on a plane built only to carry boxes. It rides in the belly hold of an ordinary passenger aircraft, beneath the cabin, in the same space where checked bags go. A long-haul widebody flying a route like Istanbul to New York might carry a full load of passengers upstairs and, at the same time, several tons of cargo below — flowers, electronics, spare parts, mail — sharing the hold with the passengers' suitcases. This belly capacity is why passenger airlines often run a cargo division most travelers never think about.

Freighter aircraft are different: cabin fittings are stripped out, or the aircraft was built without them, so the entire fuselage becomes cargo space, loaded through a large door in the nose or side. Freighters exist because belly space alone cannot handle everything that needs to fly — oversized items, very heavy shipments, or routes and time slots where passenger flights don't go. Airlines that operate scheduled freighter fleets, and forwarders that charter freighter aircraft, fill that gap.

ULDs: Standardizing the Load

Loading loose boxes into an aircraft one at a time would be slow and would waste space. Instead, cargo is built up on the ground into unit load devices, or ULDs — containers or pallets shaped to fit an aircraft's hold and secured with nets or latches. A container is a rigid box, sized to match the curve of a particular fuselage; a pallet is a flat metal sheet with a cargo net clipped over the load. Ground crews build up a ULD at a warehouse, weigh and document it, then move the whole unit onto the aircraft using a loader that slides it into place — far faster than handling each parcel individually, and it lets the same standardized units move between different aircraft and airlines.

The Air Waybill: Cargo's Paperwork

Every air cargo shipment travels with an air waybill, or AWB — the cargo equivalent of a passenger's ticket and boarding pass combined with a contract. It names the shipper and the consignee (the receiver), describes the goods and their weight, states the agreed carriage terms, and gives the shipment a tracking number that follows it to destination. A "house" air waybill is issued by a freight forwarder to its own customer, while a "master" air waybill is issued by the airline to whoever booked the space — often that same forwarder, consolidating many customers' shipments into a single ULD.

Freight Forwarders: The Middlemen

Very few individual shippers deal directly with an airline's cargo department. Instead, most cargo moves through freight forwarders — companies that sit between the shipper and the airline. A forwarder collects shipments from many customers, consolidates them into ULDs, books space on one or more airlines, arranges customs paperwork, and handles pickup and delivery on each end. For a shipper, this means dealing with one company instead of negotiating separately with airlines, customs brokers, and truckers. For an airline, it means selling large blocks of capacity to a smaller number of forwarder customers rather than many individual shippers.

What Actually Flies

A wide range of goods move by air, but they share a common trait: something about them makes the extra cost worth paying.

Integrators vs. Traditional Cargo Airlines

Two different business models move air cargo. Traditional cargo airlines, and passenger airlines' cargo divisions, sell hold space to freight forwarders, who handle the customer relationship and door-to-door logistics. Integrators, by contrast, operate the entire chain themselves: they own the aircraft, the sorting hubs, and the delivery trucks, moving a parcel from the sender's door to the recipient's door under one brand and one tracking number, with no forwarder in between.

Because they control every link, integrators can guarantee delivery times in a way a traditional forwarder-airline chain, with several separate companies involved, finds harder to match. Both models coexist because they serve different needs: a company shipping one urgent envelope wants an integrator's door-to-door guarantee, while a company shipping tons of freight on a recurring lane often works through a forwarder instead.