CAO and PAX

Introduction to aircraft types in air freight

In the air freight industry, two acronyms are frequently used to designate the types of aircraft that carry freight: CAO (Cargo Aircraft Only) and PAX (Passenger Aircraft). These terms not only refer to types of aircraft but also imply significant differences in terms of capacities, operational constraints, regulations, and costs.

The distinction between these two categories is fundamental for air freight professionals, as it directly influences logistical decisions, options available for shipping certain types of goods (especially dangerous goods), and planning and pricing strategies. Understanding the specificities, advantages, and limitations of each type of aircraft is essential to optimize air freight operations.

This section explores in detail the characteristics of cargo aircraft (CAO) and passenger aircraft (PAX) used for freight transport, their operational differences, associated regulatory considerations, and the criteria for choosing between these two options based on specific shipping needs.

CAO - Cargo Aircraft Only

Definition and characteristics of cargo aircraft

Aircraft designated as CAO (Cargo Aircraft Only) are specifically designed or modified for the exclusive transport of goods, without passengers. These aircraft are optimized to maximize cargo space and capacity, with structural features adapted to the particular requirements of air freight.

There are two main categories of cargo aircraft:

• Dedicated cargo aircraft: Designed from the outset as freighters (e.g., the Boeing 747-8F)
• Converted aircraft: Former passenger aircraft converted into cargo aircraft (e.g., Boeing 737-800BCF or Airbus A330P2F)

Structural characteristics

Cargo aircraft have several distinctive features:

• No passenger amenities: No seats, windows, entertainment systems, or passenger cabin pressurization
• Reinforced floor: Designed to support heavy concentrated loads
• Large cargo doors: Often side or front doors (nose-loading on some models like the Boeing 747)
• Integrated handling systems: Rails, rollers, and tie-down points to facilitate loading and securing of cargo
• No pressurization in some areas: Allowing the transport of certain dangerous goods
• Specialized compartments: Dedicated areas for certain types of freight (refrigerated, live animals, etc.)

Main cargo aircraft models

Among the most used cargo aircraft in the industry are:

• Boeing 747 Freighter: The "Jumbo Jet" cargo, with its various versions (747-400F, 747-8F), remains one of the largest cargo aircraft with a capacity exceeding 130 tons
• Boeing 777F: Long-range twin-engine cargo aircraft with a capacity of approximately 100 tons
• Boeing 767F: Medium-range cargo aircraft with a capacity of approximately 50-60 tons
• Airbus A330-200F: Direct competitor of the Boeing 767F with a similar capacity
• McDonnell Douglas MD-11F: Although older, still used by several cargo companies
• Boeing 737F: Used for regional operations with a capacity of approximately 20 tons
• Antonov An-124: Specialized cargo aircraft for oversized loads with a capacity of approximately 150 tons
• Antonov An-225 Mriya: The largest cargo aircraft in the world (single unit, unfortunately destroyed in 2022) with a capacity of 250 tons

Advantages of cargo aircraft (CAO)

Cargo aircraft offer several significant advantages for freight transport:

Capacity and flexibility

• Large available volume: Use of the entire interior space of the aircraft
• High load capacity: Ability to carry heavier loads
• Dimensional flexibility: Acceptance of bulky or oversized packages
• Adaptation to specific needs: Variable configurations according to freight types

Dedicated operations

• Optimized schedules for freight: Planning independent of passenger flight constraints
• Specific routes: Serving destinations with high freight demand, sometimes less served by passenger flights
• Night operations: Ability to fly at night, optimizing delivery times
• Dedicated infrastructure: Use of specialized cargo terminals

Less restrictive regulations

• Transport of dangerous goods: Ability to carry certain dangerous goods prohibited on passenger flights
• Larger authorized quantities: Higher limits for authorized dangerous goods
• Different safety constraints: Procedures adapted to freight rather than passengers

Limitations and constraints of cargo aircraft

Despite their advantages, cargo aircraft also have certain limitations:

Economic aspects

• High operating costs: Amortization over freight alone, without passenger revenue
• Generally higher rates: Costs reflected in freight rates
• Sensitivity to market fluctuations: Vulnerability to changes in freight demand
• Significant initial investment: Cost of acquiring or converting aircraft

Operational constraints

• Generally more limited frequencies: Fewer flights than passenger aircraft on most routes
• Less dense network: More restricted geographical coverage
• Infrastructure constraints: Need for specific facilities for loading/unloading
• Logistical complexity: Organization of flows to optimize filling

Environmental considerations

• Carbon footprint: Potentially higher environmental impact per ton transported
• Average age of the fleet: Frequent use of older, less efficient aircraft
• Increasing regulatory constraints: Stricter environmental standards

PAX - Passenger aircraft carrying freight

Freight transport in passenger aircraft

The term PAX, short for "passengers" in English, refers in the context of air freight to passenger aircraft primarily designed to carry passengers but which also transport goods. This freight transport is mainly carried out in two distinct spaces:

• Holds (belly cargo): Compartments located under the main deck where passenger baggage and freight are transported
• Passenger cabin: In some exceptional cases (such as during the COVID-19 pandemic), the cabin may be partially used to transport freight

Freight transport in passenger aircraft represents a significant portion of global air freight capacity. Before the COVID-19 pandemic, approximately 50% of international air freight was transported in the holds of passenger aircraft, demonstrating the importance of this "secondary" capacity in the global ecosystem of air freight transport.

Hold configuration

The holds of passenger aircraft are generally pressurized and air-conditioned, allowing the transport of a wide variety of goods, including perishable items, pharmaceuticals, and other sensitive cargo. They are equipped with restraint systems and nets to ensure the safety of the load during flight.

Advantages of PAX transport

Global capacity of the air network

• Network density: Passenger aircraft serve a multitude of destinations worldwide, including secondary airports
• High frequency: Many daily flights offering varied options for rapid shipping
• Optimization of deadlines: Easy access to major transit platforms and intercontinental hubs

Pricing flexibility

• Cost sharing: Freight is a complementary source of revenue to passengers, reducing its unit cost
• Competitive offers: Advantageous pricing on certain routes due to excess passenger capacity

Operational responsiveness

• Daily carrying capacity: Ideal for regular flows, small volumes, and urgent shipments
• Flexibility: Ability to ship quickly without waiting for a cargo aircraft to be fully loaded

Limitations of PAX transport

Volume and weight constraints

• Limited capacity: Hold space restricted by passenger baggage
• Maximum dimensions: Restrictions on the size of accepted packages
• Limited weight: Lower capacity than cargo aircraft, especially for heavy loads

Stricter regulations

• Restrictions on dangerous goods: Many products are prohibited on board passenger aircraft
• Enhanced safety procedures: Compliance with passenger standards (screening, documentation, etc.)

Risks of disruption

• Dependence on passenger variables: Delays, cancellations, or aircraft changes impacting hold availability
• Seasonal variability: Hold capacity varies depending on the period and tourist demand