An airplane’s cargo compartment is something people are very curious about. The image movies project is that of a huge and open-plan space, which can be easily accessed during the flight, and it is full of hiding places where any persecution is possible. Well, nothing could be further from the truth. This space, which occupies practically the same area as the passenger cabin, is intended for luggage and goods placement. In short, the airplane’s cargo hold function is to house passengers’ suitcases and transport different items that, due to their characteristics, it is advisable to transport by air.
This compartment is usually divided into different parts separated by sizes. Their number varies according to the airplane model, ranging from one to six. For example, the A320, A321, A330 and A350 have holds 1,2,3,4 and 5, while the A319 only have holds 1,4 and 5. Most airplanes have a slightly smaller cargo hold where late connections luggage or removed from the passenger cabin, such as baby carts, is placed.
These air cargo holds have special panels on walls and ceiling that, besides allowing their depressurization without causing structure damage, serve to hide and protect all cables and pipes that run through the area and are at risk breaking due to possible load impacts, so they are under constant supervision. Likewise, at least one (usually the front one) will be pressurized and heated to transport live animals and/or merchandise that requires a temperature control such as vaccines, flowers or perishable foods. Normally, the temperature can be regulated between zero and 20/25 degrees Celsius.
In addition, these compartments have several safety systems such as smoke/heat detectors and fire extinguishing. Also, the airplane air conditioning system is designed in such a way that the air moves from the passenger cabin to the holds, and from there either to the outside or to the compressors, where it mixes with new air and returns, after passing through the HEPA filters, to the passenger cabin. This circuit prevents odors, gases or fumes that may appear in the hold from reaching passengers.
On the other hand, in some airplanes, under the cockpit is the so-called avionics compartment where most computers of the different airplane’s systems are located, and which can be accessed through a hatch on the floor.
Checked baggage is that which, due to its size and/or weight, is not allowed in the passenger cabin so it must be checked in at the departure airport to pick it up on the belt at destination. This luggage must have certain measures and weight. These will depend on the company and the class we travel in. As a rule, airlines accept luggage up to 23kg although some extend it to 32kg with an additional charge. In contrast, the so-called low-cost airlines reduce it to 20kg.
Checked baggage is subject to certain restrictions and, although it is possible to carry practically all type of objects for personal use, there is a list of items considered dangerous to travel in the baggage compartment and of which the passenger is informed when buying the ticket. Among them are:
The carrying capacity of an airplane will depend on its own design. There are airplanes aimed to transport only goods, while others may be used for both, cargo and passengers. These are called mixed airplanes as can be adapted to transport cargo and passengers or only cargo.
Among the models most used for mixed transport we find the Airbus 319/320/321 family used interchangeably for cargo and passenger transport, with a maximum capacity of 1.5 tons. Also, within Airbus, we find as mixed models two large airplanes with important services for goods freight. The A-340 has a wide operational range of 12000 to 15000 km and a design that allows an easy pallet loading and unloading, with a maximum capacity of 16 tons. On the other hand, the A330 may carry 5 pallets plus loose load, with a maximum load of 10.3 tons.
Talking of Airbus models converted into just cargo airplanes, we find:
On the other hand, Airbus also has the Beluga family, which is specially designed to carry bulky and heavy loads. The Beluga ST, for example, has a cargo capacity of around 47 tons and a distinctive “whale” shape that allows it to accommodate large airplane components.
A curiosity about Airbus in its wide-body models for mixed transport, is the design of a resting area for cabin crew, which is located at the rear hold. It is basically a cargo container with beds. This area cannot be occupied in takeoffs and landings, it is accessed through a staircase in the passenger cabin and has an escape hatch to the same cabin.
Changing to Boeing brand, we also find different models of both, mixed and converted. Among the first ones we can find:
If we talk about models designed exclusively as cargo airplanes, the Boeing 747 F Freighter, with a capacity of up to 107 tonnes, and the Boeing 747-400 ERF, with a capacity of up to 112 should be noted. In fact, 99.5% of freight could be carried on one of these models. However, Boeing offers versions of its mixed models converted into freighters:
Lastly, we cannot overlook the legendary Antonov An-225 Mriya, which held the world record as the heaviest cargo aircraft with the largest wingspan.
The Antonov An-225 was an aviation icon and the greatest creation of the Ukrainian company Antonov, also known for the Antonov An-124 Ruslan. The Mriya, originally designed to transport the Soviet space shuttle, had the capacity to carry up to 250 tons of cargo. Unfortunately, it was destroyed during the Russian invasion of Ukraine in 2022, but its legacy remains a symbol of technological advancement in cargo aviation.
Depending on the airplane, baggage and cargo may go loose inside the hold, held by a net so that they do not move, or in some type of container or pallet. The former compartments are called bulk warehouses and the second palletized.
In the first case, the most basic way to be loaded/unloaded is with one or two workers inside the hold who place/remove packages. In the palletized holds, the floor has motorized rollers that move the containers. Once in position, the stops are set so that the container or pallet does not move from its position during the flight.
Some airplanes have sliding surfaces to facilitate work. Once placed on these, suitcases or cargo slide towards the back, leaving the second section visible and, thus, filling the room until reaching its maximum capacity.
The correct placement and stowage of freight is crucial for the success of the flight operation. Therefore, it is very important to consider weight and its distribution. The pilot must know all airplane’s weights (empty, take-off, landing, maximum with zero fuel…) as well as the load placement since it will affect the plane’s center of gravity and, therefore, its maneuverability. If the center of gravity is towards the front, the flight will be more stable, but maneuvering will be more difficult as more force must be applied on controls. On the other hand, the closer freight is to the nose, the more fuel consumption will be generated, and the airplane’s stall speed will increase. On the contrary, if the center of gravity is further to the rear, the flight will be more unstable, but maneuvering will be easier and fuel consumption and stall speed will be reduced.
Air shipment is one of the most widely used means of transport. Although expensive, speed is its most outstanding advantage. There are goods that due to their nature, can only be transported by this mean. Let’s see some of them:
Air cargo shipments must comply with the customs provisions of the country of origin and the country of destination. For this reason, air cargo can only be shipped to and from airports with the necessary customs clearance.
As we have seen, an airplane’s holds are not simply spaces to fill up with luggage or goods as if they were a car’s trunk. The complexity of the flight operation requires that everything on board travels in a controlled manner and both nature and weight, must be reflected in the so-called load sheet for the maximum optimization of the airplane’s resources and the success of the operation.
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