Two ways to put freight on an aircraft
Freight flies in two main ways. The first is belly cargo, which is carried in the lower hold of a passenger aircraft, beneath the cabin, alongside passenger baggage. The second is a freighter, an aircraft built or converted to carry cargo only, often with a main deck that can hold large pallets. Many airlines operate both, and the same parcel might use one or the other depending on route, timing and the carrier’s plans.
How belly cargo works
On a passenger flight, the hold’s space is shared. Baggage has priority, and the airline sells what is left to freight customers. That has several consequences.
- Capacity depends on the passenger operation. The amount of space varies with aircraft type, passenger numbers and baggage volumes. Wide-body aircraft on long routes typically offer much more freight space than small narrow-body aircraft.
- Schedules follow passenger demand. Flights run where and when passengers want to travel, which often means frequent departures on busy city pairs and few on thin routes.
- Shape limits apply. Hold doors and compartment heights restrict the size of packages and the pallets that can be used. Unusually tall or heavy items may not fit.
- Dangerous goods are more restricted. Some items allowed on a freighter are not accepted in a passenger aircraft, or only in limited quantities. Batteries and liquids are the usual examples.
- Cost is shared. Because the aircraft flies mainly for passengers, belly freight can sometimes be sold at attractive rates, especially on routes with plenty of capacity.
If a flight is cancelled or an aircraft is swapped for a smaller one, belly freight may be offloaded or delayed. Cargo that is loaded late may also be bumped if baggage or fuel needs take priority.
How freighters work
A freighter is operated for cargo. Freighters can be run by major airlines, by specialist cargo airlines or by express integrators that use them for their own networks.
- Higher capacity per flight. Large freighters can carry many tonnes on the main deck and lower hold.
- Larger items. A nose or side cargo door allows tall, long or heavy items that could not go through a passenger hold door.
- Flexible schedules. Freighter flights are planned around cargo demand, often at night or at times that suit a network, and may connect hubs rather than tourist destinations.
- Wider dangerous goods acceptance. Freighters can often accept items that are prohibited on passenger aircraft, subject to the regulations and the airline’s own rules.
- Higher fixed cost. The aircraft must be paid for by cargo alone, so it is sensitive to load factors and to the balance of freight in each direction.
Express carriers use freighters heavily for overnight services, using a hub and spoke design. Freighter flights typically run on a fixed timetable that matches the sorting windows at the hubs.
Side-by-side comparison
| Factor | Belly cargo | Freighter |
|---|---|---|
| Capacity per flight | Varies with aircraft and baggage | Generally larger and more predictable |
| Route network | Wide, follows passenger routes | More selective, follows cargo demand |
| Frequency | Often high on busy routes | Depends on the operator |
| Package size | Limited by hold doors | Larger items can be accepted |
| Dangerous goods | More restricted | Often wider acceptance |
| Schedule certainty | Affected by passenger operations | Planned around cargo |
This is a general picture. Individual airlines and aircraft types differ, so treat the table as a starting point.
Why the balance changes
The mix between belly and freighter capacity shifts over time. When passenger flying expands, belly space increases and can put downward pressure on rates. When passenger flights are reduced, as during major disruptions, belly capacity falls and freight may move to freighters or wait. The effect on prices feeds into air freight rates, though it is only one factor among several.
What it means for a parcel shipper
Most small shippers do not choose between belly and freighter directly. A forwarder or carrier makes the choice. But the difference can affect you in several ways:
- Service reliability. A parcel moving on a thinly flown route with only a few flights a week depends on the capacity of those flights.
- Product limits. If you ship batteries, aerosols or oversize goods, ask which aircraft types the service uses.
- Transit time. A route with several daily passenger flights may offer faster rebooking if one is missed, while a weekly freighter may not.
- Price. Rates may reflect which type of capacity is used, though a quote rarely says so.
When requesting a quote, ask whether freight is booked on a specific flight, whether there are restrictions on item size, and what happens if the first flight is full. Where goods are time-critical, a service with guaranteed space may be worth the extra cost; where they are not, a deferred service on whatever capacity is available can be cheaper. Comparing options by service levels is a useful habit for any shipper.