Aircraft Cargo Compartments Classification

Aircraft Cargo Compartments Classification


In this article, you will read about the subject related to the aircraft airworthiness certification, it is about aircraft air cargo compartment classification. If you don't work on the cargo section, for sure you do not have any idea about it.

The major risk is fire and fire class, regulators required many standards to protect cargo compartment from fire risk. This can be achieved by fire protection and suppression systems.

According to ICAO ANNEX 8 [ also FAA Part 25 of EASA CS-25], the requirements of Cargo compartment protection :

Types of Fires 

There are several different classifications for fires [Not all fires are the same], and fire classification has not linked with the cargo compartment classification.

Fire may be classified into one or more fire classes. By knowing the fire class we respond to fire risks by using fire extinguisher which is rated for the types of fires to effectively putting it out. You need to understand what each fire class means before we go to the aircraft cargo compartment classification.  And by reading this article you will be prepared for the next article which is relating to using passenger aircraft to load cargo in both passenger cabin and cargo holds.

  1. Each cargo compartment accessible to a crew member in a passenger-carrying aircraft shall be equipped with a fire suppression system.
  2. Each cargo compartment not accessible to a crew member shall be equipped with a built-in fire detection system and a built-in fire suppression system; and
  3. Cargo compartment fire suppression systems, including their extinguishing agents, shall be designed to take into account a sudden and extensive fire such as could be caused by an explosive or incendiary device or dangerous goods.

Before we talk about the aircraft cargo compartment classification, I will give you short details about the type of fires.

Class A 

Class A fires are fires in ordinary combustibles such as wood, paper, cloth, rubber, and many plastics. Trash fires are one such example. Class A fires are commonly put out with water or any suitable extinguishing agents.

Class B 

Class B fires are fires in flammable liquids such as gasoline, petroleum greases, tars, oils, oil-based paints, solvents, alcohols.  Class B fires also include flammable gases such as propane and butane. Extinguishing these types of fires to remove oxygen is a common solution as are chemical reactions that produce similar effects.

Class C 

Class C fires are fires involving energized electrical equipment such as computers, servers, motors, transformers, and appliances. To extinguish such fires you cut the power off and use non-conductive chemicals to extinguish the fire, by Removing the power the Class C fire becomes one of the other classes of fire.

Class D 

Class D fires are fires in combustible metals such as magnesium, titanium, zirconium, sodium, lithium, and potassium. Class D fires are a danger in laboratory environments. Common extinguishing agents such as water are ineffective and can be hazardous. To extinguish a Class D fire, use a dry powder agent. This absorbs the heat the fire requires to burn and smothers it as well.

Class K 

Class K fires are fires in cooking oils and greases such as animal and vegetable fats. Wet chemical fire extinguishers have become popular in putting out these types of fires.

Now, we understand all types of fires and the correct extinguishing agent which is used to fight each type of fire, some types of fire extinguishing agents can be used on more than one class of fire. Others have warnings where it would be dangerous for the operator to use on a particular fire extinguishing agent.

Before we start listing the Aircraft Cargo Compartments classes, let us have a view about how cargo compartment fire protection work.

Aircraft Cargo Compartment Fire Protection 

There are many fire protection methods which are used to protect air cargo loads inside the aircraft cargo compartments, such as:

  1. by regulating the load and condition of transport.
  2. Protecting the outside of compartment from internal hazards created by fire. e.g. heat and fumes/smoke.
  3. Controlling the fire e.g no Oxygen.

Aircraft Cargo Compartments Classification 

Aircraft Cargo compartments are classified [ in most national airworthiness requirements ] as follows:

Class A Aircraft Cargo Compartment 

A Class A cargo or baggage compartment is one in which:

  1. the presence of a fire would be easily discovered by a crew member while at his or her station; and
  2. each part of the compartment is easily accessible in flight.

Class B Aircraft Cargo Compartment 

A Class B cargo or baggage compartment is one in which:

  1. there is sufficient access in flight to enable a crew member to effectively reach any part of the compartment with the contents of a hand fire extinguisher.
  2. when the access provisions are being used, no hazardous quantity of smoke, flames or the extinguishing agent will enter any compartment occupied by the crew or passengers; and
  3. there is a separately approved smoke detector or fire detector system to give warning at the pilot or flight engineer station.

Class C Aircraft Cargo Compartment 

A Class C cargo or baggage compartment is one not meeting the requirements for either  - Class A or B compartment but in which:

  1. there is a separate approved smoke detector or fire detector system to give warning at the pilot or flight engineer station;
  2. there is an approved built-in fire-extinguishing system controllable from the pilot or flight engineer station;
  3. there are means of excluding hazardous quantities of smoke, flames, or extinguishing agent from any compartment occupied by the crew or passengers; and
  4. there are means of controlling ventilation and draughts within the compartment so that the extinguishing agent used can control any fire that may start within the compartment.

Class D Aircraft Cargo Compartment 

A Class D cargo or baggage compartment is one in which:

  1. a fire occurring in it will be completely confined without endangering the safety of the aircraft or the occupants;
  2. there are means of excluding hazardous quantities of smoke, flames, or other noxious gases from any compartment occupied by the crew or passengers;
  3. ventilation and draughts are controlled within each compartment so that any fire likely to occur in the compartment will not progress beyond safe limits; and
  4. consideration is given to the effect of heat within the compartment on adjacent critical parts of the aircraft.

Class E Aircraft Cargo Compartment 

>A Class E cargo compartment is one on aircraft used only for the carriage of cargo and in which:

  1. there is a separate approved smoke or fire detector system to give warning at the pilot or flight engineer station;
  2. there are means of shutting off the ventilating airflow to or within the compartment, and the controls for these means are accessible to the flight crew in the crew compartment;
  3. there are means of excluding hazardous quantities of smoke, flames, or noxious gases, from the flight crew compartment; and
  4. the required crew emergency exits are accessible under any cargo loading conditions

Now, I am sure you understood each cargo compartment class. But you don't know where are the locations of them on the aircraft body.

Aircraft Cargo Compartment Locations 

Class A Cargo Compartment 

Class A cargo compartments are small cargo compartments that may be located between the flight deck and the passenger cabin or adjacent to the galley area or at the back of the aircraft.

Class B Cargo Compartment 

A Class B cargo compartment is usually much larger than a Class A cargo compartment and can be located in an area remote from the flight deck. Class B cargo compartments are found on “combi” aircraft between the flight deck and the passenger cabin or behind the passenger cabin at the rear of the aircraft.

Note.— A “combi” aircraft is one in which both cargo and passengers are carried on the main deck.

Class C Cargo Compartment 

It's large in volume, the volume of a Class C cargo compartment is usually larger than Class A or B and such cargo compartments are generally found under the floor in wide-bodied aircraft. A Class C cargo compartment may have two fire extinguishing systems, enabling a second charge of extinguishant to be fired into the cargo compartment sometime after the fire has initially been controlled by the first charge.

Class D Cargo Compartment 

Instead of being equipped with fire detection and extinguishing systems, Class D cargo compartments are designed to control a fire by severely restricting the supply of oxygen.  Class D cargo compartments are to be found under the passenger cabin floor on most jet transport aircraft. However, it must be appreciated that certain dangerous goods are themselves, oxygen producers. Therefore, it cannot be assumed that a fire in a Class D cargo compartment will necessarily self-extinguish.

Class E Cargo Compartment 

A Class E cargo compartment normally comprises the entire main deck compartment of a cargo aircraft.


For certification, cargo compartments must comply with different performance standards. Which are mentioned above

During COVID-19 period, airlines had used passenger caboin to load cargo. my question is, what kind of materials are permitted to be loaded in the passenger cabin?

Of course, the second choice is combustible materials such as wood, cloth, paper. You know why !! because passenger cabin not certified to carry dangerous goods, it is classified as Class A Cargo Compartment. dangerous goods on class A is not permitted.

Maged Saeed AL-Hadabi

I’m Instructor / Maged Saeed Al-Hadabi. ​ Air Cargo / IATA Dangerous Goods Regulations / Safety Management System Senior Instructor, Auditor [ Yemen Airways] . Approved IATA DGR/ SMS Instructor by Yemen Civil Aviation Authority. We hope you find Aviation Professional website not only informative, but interesting and helpful as well. Leave your comment , thank you.

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