Towards More Sustainable Planning Decisions Around Airports: Investigating Global Airport Classifications and Proposing a Four-Tiered System for Australia

Abstract

Airports differ vastly in purpose, scale, land use and activities. Although several criteria and definitions have been used to classify airports worldwide, no universally accepted classification currently exists. The lack of standardisation means an airport could fall under multiple overlapping categories, creating confusion and obscuring its actual role. Australia also lacks an official system that reflects the diverse nature of its airports. This paper addresses that gap by proposing a holistic and integrated four-tiered classification framework for Australian airports. Drawing on an international literature review and comparative policy analysis, the classification is based on four criteria: airport location, governance, network function and passenger profile. To illustrate its practical application, the system is applied to case studies of selected airports representing each tier, as well as airports that overlap between tiers. The proposed classification has the potential to enable more strategic, coordinated and sustainable infrastructure investment and land use decision-making around airports.

1. Introduction

Airports vary in purpose, scale, land use, activities and relationships with their surrounding regions. Given such complexity, national governments and international agencies employ airport classification for several purposes, including slot allocation (designated time intervals for an aircraft to land or depart at an airport), network management, public allocation funding, competition assessment, security regulations or setting use charges [1]. However, no universally accepted classification of airports currently exists [2]. There are many ways to categorise an airport, using a variety of factors and circumstances, including the airport’s historical context, functions, political power and other geographical factors. Todd et al. [2] (p. 143) observe that relying on these broad factors has led to “a simplification of the true role of any airport, trading sophistication for clarity”. They argue, however, that airport classification is useful as it allows some degree of categorising airport infrastructure, thus allowing generalisation. Additionally, due to the lack of standardised classification, an airport could fall under several categories from various authorities worldwide, all of which employ different terms and criteria.

There is no official Australian airport classification that comprehensively captures the characteristics and context of airports despite the critical role of airports in connecting cities and towns across a geographically vast country. The only official Australian classification currently applies to its international airports. While the Australian Airports Association (AAA) offers a tiered classification system, it lacks detailed explanations for how each application of each tier. This can lead to inconsistent interpretations and limits its usefulness for decision-making. For example, Gold Coast Airport and Cairns Airport are categorised as ‘regional’ despite having higher passenger volumes than some capital city airports. Similarly, the existing paradigm of grouping all privatised airports as ‘major airports’ can misrepresent their actual activity levels. These gaps highlight the need for a clearer, more consistent classification that holistically considers airport characteristics and contexts.

To address these issues, the aim of this paper is to develop a conceptual classification for civil airports in Australia that holistically considers their key characteristics. Three objectives underpin this aim: (1) to explore how airports are classified in the literature and globally, (2) to review classifications currently in use for airports in Australia and (3) to develop a classification for Australian airports using the findings from the two prior objectives. To achieve the aim and objectives, the paper first details the methodology of the study. It then reviews the literature on how airports are classified. Subsequently, the paper analyses relevant policy documents, including official and unofficial classifications and categories for airports worldwide and in Australia. The literature review and policy analysis findings are then synthesised into a four-tiered classification system for Australian airports. The classification is also applied to selected airports to demonstrate its practical use. The paper then explores various ways in which the system can support government decision-making, ultimately promoting economic, environmental and social sustainability. The paper concludes with a discussion of the potential applicability of the conceptual classification to other countries, as well as an outline of the limitations and future research directions for the proposed system.

2. Methodology

To develop the conceptual classification for Australian airports, this study employed a qualitative research design comprising four scaffolded steps: (1) a literature review, (2) a comparative policy analysis, (3) development of the proposed framework and (4) application of the proposed framework. This approach enabled a comprehensive exploration of airport classification frameworks across jurisdictions and facilitated the development of a context-specific classification for Australia.

Firstly, the literature review examined peer-reviewed publications on airport classifications, with an emphasis on identifying commonly used classification criteria. Secondly, the comparative policy analysis examined airport classification systems in the United States, the United Kingdom, Europe and China. These jurisdictions were selected due to the maturity, diversity and policy innovation of their airport networks. Existing airport classifications in Australia were also evaluated to determine their application and limitations, as well as to explore the diverse nature of Australian airports. Thirdly, key criteria for an Australian airport classification system were established, based on the international review of airport classification systems and the characteristics of Australian airports. This led to the development of a four-tiered framework for classifying Australian airports based on geographical and operational characteristics. Lastly, to illustrate the practical applicability of the proposed framework, it was applied to a set of airport case studies representing each tier. These case studies were chosen to portray the diversity of airport types captured across the four proposed tiers, including examples from capital cities, major regional centres, regional towns and remote communities. The case studies showcase the classification system’s ability to distinguish airport characteristics in a manner that is both consistent and policy-relevant. This application highlights the classification framework’s utility in supporting planning, regulatory and investment decisions. Figure 1 provides a visual summary of the four steps employed in the study’s methodology.

3. Literature Review: Diverse Perspectives in Airport Classification

3.1. Airport Classification Studies

Past studies have employed different definitions of airport types [3]. According to Chen et al. [4], airport classification studies are highly varied—an unsurprising trend given their diverse geographical and geopolitical factors. They propose that airport classification studies have fallen into three categories. The first category involves using single or single-type indicators—such as the airport’s function as a hub [5]. The second type of study utilises multiple indicators, capturing airport properties and geographical factors. The third approach involves developing a ‘synthetic cross-network indicator system’, combining aspects of the first two techniques and including other modes of non-air transport [4]. Chen et al. [4] highlight that basic airport classification studies employing single or single-type indicators tend to rely on passenger volumes or types of airport services and produce results that are broad but limited in nuance. Nevertheless, more recent studies have increasingly employed the second approach, combining simple indicators with various geographical factors and regional economic influence.

Table 1. Airport classification criteria employed in the literature.

Source	Scope	Classification Criterion/Criteria
[6]	Worldwide	Portion of passenger traffic in the same ‘multiairport system’
[7]	The United Kingdom and the United States	(1) Geographical scale of the airport (e.g., national, regional or international airport) (2) The airport’s role (e.g., origin and destination or hub airport)
[8]	United States	Three categories of airports in the same metropolitan area (i.e., a ‘primary’ airport, other ‘core’ airports and ‘fringe’ airports), based on the following attributes: (1) Portion of passenger traffic in the metropolitan area (2) Distance to the primary airport, which determines the ‘core’ or ‘fringe’ status
[1]	United States	Three-tier hierarchy based on the airport’s hubbing activity indicators, including traffic generation and connectivity
[9]	Worldwide	Freight activity indicators, including the following: (1) Annual freight volume (2) The proportion of freight volume compared to all airport activities (3) The proportion of freight aircraft compared to all commercial aircraft (4) The proportion of international freight compared to all freight
[10]	Worldwide	Identification of multiple airport regions (MARs) based on the following factors: (1) Airport passenger traffic (2) Temporal distance between airports
[3]	Worldwide	Five-tier hierarchy, with each tier containing up to two types of airports, based on the following characteristics: (1) Continental aircraft traffic shares (2) Proximity to other airports in the same network (3) Hubbing potential based on connectivity level
[4]	China	(1) Interaction between air and high-speed rail (2) Airport’s properties, including the number of seats, number of carriers, airport competitors, routes and destinations

summarises the principal criteria employed in selected airport classifications.

As illustrated in Table 1, multiple studies have employed various criteria in their airport classifications, with passenger traffic as a commonly used criterion. Several studies have also utilised the relationship between nearby airports—grouped into one ‘region’, ‘system’ or ‘area’—as an essential consideration in their classification approach.

3.2. International Classification Systems

Internationally, two agencies play a significant role in governing commercial aviation operations: the International Civil Aviation Organisation (ICAO) and the International Air Transport Association (IATA). The ICAO’s Aerodrome Reference Code, included in the organisation’s Annex 14—a document establishing Standards and Recommended Practices (SARPs) for airport design and operations—can be used to categorise airports [11] (The Aerodrome Reference Code specifies the maximum size of aircraft for which an airport is designed based on three criteria: runway length, wingspan and outer main gear wingspan). In the same document, the International Civil Aviation Organization [12] also employs peak-hour aircraft traffic volume to classify airport traffic density into light, medium and heavy categories. Meanwhile, the IATA employs the Worldwide Airport Slot Guidelines to allocate airport slots by designating airports as Level 1, Level 2 or Level 3 depending on their potential congestion level [13].

Having explored how airports have been classified in past studies, the paper next discusses airport classifications currently employed in different regions, including the United States, the United Kingdom (UK), Europe and China.

3.3. Airport Classifications: Policy Examples from the United States, the United Kingdom, Europe and China

3.3.1. United States

In the United States, airports are classified by the Federal Aviation Administration (FAA), which publishes and annually updates the National Plan of Integrated Airport Systems (NPIAS). The NPIAS assists the FAA in coordinating and funding the system of 3287 public-use airports nationwide under the federally run Airport Capital Improvement Program over a five-year timeframe. The document groups these airports into two major categories: primary and nonprimary [14]. Most (2904 or 88.3%) of the public-use airports covered by the NPIAS are nonprimary airports. The document also employs statute categories, defined in Title 49 of the United States Code and outlined in

Table 2. Statute categories of public-use airports in the United States [15].

Category	Description
Primary Airports
Commercial Service Airports	Publicly owned airports that facilitate more than 10,000 passenger boardings annually and receive scheduled passenger service Further classified into four ‘hub’ categories (large hub, medium hub, small hub and nonhub primary) based on their percentage of national passenger boardings
Nonprimary Airports
Commercial Service Airports	Publicly owned airports that facilitate between 2500 and 10,000 passenger boardings annually and receive scheduled passenger service Also referred to as ‘nonhub nonprimary’
Reliever Airports	Help relieve congestion at a commercial service airport and facilitate general aviation access for the community
General Aviation Airports	Airports with no scheduled passenger service or with scheduled service that facilitates less than 2500 passenger boardings yearly

, to categorise the airports.

In addition to those listed in Table 2, the Federal Aviation Administration [16] also specifies another category, ‘Cargo Service Airports’, comprising airports served by cargo aircraft carrying no passengers, with a total landed weight exceeding 100 million pounds. An airport can be concurrently categorised as both a Commercial Service Airport and a Cargo Service Airport. Following cooperation with aviation stakeholders and a national review of General Aviation Airports, the FAA published General Aviation Airports: A National Asset in 2012. The document provides a further policy-based categorisation of nonprimary airports, classifying them as ‘national’, ‘regional’, ‘local’, ‘basic’ and ‘unclassified’ based on their existing activity, geographic factors and public interest functions [14]. Notably, ownership is a common criterion determining the applicable category for an airport across both the statute and policy-based airport categories employed by the FAA.

3.3.2. United Kingdom

The UK Government’s White Paper on Airports Policy specifies four airport categories: ‘gateway international airports’, ‘regional airports’, ‘local airports’ and ‘general aviation airports’ [17]. All the Gateway International Airports, except Manchester Airport and Glasgow Prestwick Airport, were in London [18]. Unlike the other three airport categories, Gateway International Airports served international flights. Following the White Paper publication, the UK Government encouraged additional investment in major regional airports to meet local demand and “shift the burden away from the London area airports” [19]. The government also promoted the further development of Manchester Airport as the principal Gateway International Airport outside the London area [19]. However, in the 1980s, the UK Government abolished this official classification, shifting towards market-driven approaches and believing strict categorisation would hinder airports from developing efficiently in response to passenger demand [20].

More recently, Butcher [21] employs the term ‘regional airport’ to refer to a UK airport outside South East England, a commonly employed approach in airport-related publications in the UK. Likewise, the Environment, Transport and Regional Affairs Committee [22] refers to all UK airports other than the five ‘London airports’—including Heathrow, Gatwick, Stansted, Luton and London City airports—as ‘regional airports’. Similarly, the Civil Aviation Authority [23] uses the term ‘regional airport’ in its Aviation Trends report for the third quarter of 2018 to refer to all airports that do not fall under its ‘London airports’ category.

The six ‘London airports’, as of January 2023 [24], are not the six busiest airports in the UK in terms of terminal passenger volume—although four of them, namely Heathrow, Gatwick, Stansted and Luton, are in the top five. All six airports, however, are located in the London metropolitan area and are the only international airports in the region. The ‘London airports’ comprise the ‘London Airport System’, the busiest network of nearby airports worldwide by passenger volume [25]. London City and Southend airports service a significantly smaller number of passengers than the other ‘London airports’—3.2 million and 89,000, respectively, in comparison to Heathrow and Gatwick airports, which served 64.5 and 34.2 million passengers, respectively, in January 2023 [24]. As such, passenger volume at individual airports is a less important criterion in the UK’s classification of ‘London airports’ and ‘regional airports’. Instead, the cumulative number of passengers of the larger airport ‘system’ or ‘network’ that an airport is part of could be seen as a more relevant criterion for the country’s airport classification.

The cluster of ‘London airports’ resides within the expansive metropolitan vicinity of London and collectively handled 60.7% of the nation’s air passenger traffic between February 2022 and January 2023 [24]. Consequently, these pivotal airports play a momentous role within the UK aviation sector, reflecting the metropolitan primacy structure wherein London substantially surpasses all other cities, including Birmingham, in terms of population. Thus, the six ‘London airports’ are classified based on three primary criteria, namely: (1) the spatial location of the airport, i.e., whether it falls within or outside the London metropolitan area, (2) the airport’s function as an international airport and (3) the magnitude of passenger traffic cumulatively managed by the airport system that the airport is part of.

Nevertheless, one major downside of the UK’s unofficial airport classification system is the large degree of simplification applied to ‘regional airports’, referring to all other airports in the country that are not ‘London Airports’. Several regional airports manage a large passenger volume, e.g., Manchester, Edinburgh and Birmingham airports, which serviced 24.2 million, 11.8 million and 10 million passengers, respectively, between February 2022 and January 2023 [24]. In contrast, other regional airports handle a significantly smaller number of passengers, e.g., Southampton and Tiree airports, which serviced 658,000 and 11,000 passengers, respectively, over the same period. Furthermore, many regional airports also handle a larger passenger volume than two of the six London airports: London City and Southend airports.

3.3.3. Europe

No integrated and complete airport classification uniformly applies to European airports [26,27]. The European Parliament, European Council, European Commission and Committee of the Regions each employ their own classification systems. However, these classifications consider only passenger volume as the sole criterion for airport categorisation [26]. Interestingly, European airport classification has received considerable attention from scholars in recent years (e.g., [26,27,28,29]), possibly attributable to the lack of an integrated classification for the whole continent.

3.3.4. China

The Civil Aviation Administration of China (CAAC) classifies four types of airports in the Civil Aviation [2018] No. 18 document as a basis for setting airport charges [30]:

• Primary Airport, class 1—including three airports (Beijing, Shanghai Pudong and Guangzhou);
• Primary Airport, class 2—including three airports (Shenzhen, Chengdu and Shanghai Hongqiao);
• Secondary Airport—including 20 airports (e.g., Kunming, Hangzhou, Wuhan and Qingdao);
• Tertiary Airport—including all other airports.

Similarly to Europe’s airport classifications, the primary criterion for the CAAC’s airport classification appears to be passenger volume. This observation is grounded in the fact that all six Primary Airports are amongst the country’s top ten busiest airports by departing seats as of May 2025 [31].

4. Australian Airport Classifications and Their Limitations

Australia’s official airport classification is limited to international airports only and considers border facilities and services at these airports. Although a new airport categorisation was recently introduced, its scope is only intended for determining each airport’s requirements for security screening measures [32]. The international airport classification system is specified under Section 9 of the Air Navigation Act 1920. Depending on the range of border facilities and onsite services, an airport is designated as an ‘international airport’ with one of the categories outlined in

Table 3. Categories of international airports in Australia under the Air Navigation Act 1920 [33].

Category	Description
Major International Airport	An airport of entry and departure, open to both scheduled and non-scheduled flights, where all procedures related to customs, immigration and quarantine are available
Restricted Use International Airport	An airport of entry and departure where all procedures related to customs, immigration and quarantine are available on a restricted basis only to flights with prior approval
Alternate Airport	An airport specified in the flight plan at which a flight may land if it is inadvisable to land at the originally designated airport
International Non-Scheduled Flight Airport	An airport where international non-scheduled flights may be granted with approval and no other form of international operation is permitted
External Territory International Airport	An airport located in an Australian External Territory where international flights can enter and depart, and all procedures related to customs, immigration and quarantine are available

.

To enhance the country’s aviation security, the Federal Government recently introduced a risk categorisation framework for Australian airports through the Aviation Transport Security Amendment (Security Controlled Airports) Regulations 2019, which was in effect from December 2019 to December 2020. The seven-tiered classification considers the overall risk profile of airports, evaluating their regional attributes, operating context and existing threat and security environments [32].

Australia’s airport sector is represented by the AAA, a peak national body with more than 340 airports and aerodromes as member organisations. According to Merkert [34], the AAA categorises its member airports and aerodromes into the following seven tiers:

• Tier 1 Capital City Airports;
• Tier 2 Non-Capital International Gateway Airports;
• Tier 3 Major Regional Airports with direct interstate services;
• Tier 4 Major Regional RPT airports without direct interstate services, servicing more than 20,000 passengers (RPT denotes Regular Public Transport, referring to scheduled commercial flights “on which seats and/or cargo space is available to the general public” [35]);
• Tier 5 Regional Airports without direct interstate services, servicing less than 20,000 passengers;
• Tier 6 Regional Airports without Regular Passenger Transport (RPT) services;
• Tier 7 Remote Community Aerodromes (used for medical emergencies).

The AAA [36] also suggests that Australia’s airport industry comprises four broad categories, outlined in

Table 4. The Australian Airports Association’s categories of airports in Australia [36].

Category	Description
Capital city and major privatised airports	Airports located in the capital city of a state/territory, e.g., Sydney and Melbourne, all of which have been privatised under the Airports Act 1996
Regional airports	Airports located in a regional area, the majority of which were owned and operated by the Federal Government, primarily for the military before being transferred to the management and ownership of their respective local governments
Department of Defence airports	Airports owned and operated by the Department of Defence
Completely privately owned airports and air strips	Airports and air strips that are privately owned

.

Most airports in Australia are ‘regional airports’, which play a significant role in the Australian aviation industry due to the beneficial outcomes they facilitate for regional communities such as connecting regional and rural areas with major cities, emergency medical services, aerial firefighting, agricultural activities, pilot training and aerial photography [36] (p. 7). These diverse activities position regional airports as important economic and social assets for regional Australia. Regional airports are estimated to account for 45% of Australia’s tourism industry and facilitate 12% of annual domestic trips [37].

Donehue and Baker [38] employ the acronym RRR to refer to remote, rural and regional airports in their investigation of challenges faced by airports in non-metropolitan Australia. They utilised the Australian Standard Geographical Classification (ASGC) Remoteness Structure, illustrated in Figure 2, to categorise RRR airports, most of which are owned and managed by local governments, into the following three sub-categories:

• Regional airports, located in ‘Inner Regional Australia’ and providing RPT to capital cities, ‘Outer Regional Area’ and ‘Remote Australia’;
• Rural airports, located in ‘Outer Regional Australia’ and facilitating both RPT services and general aviation activities; and
• Remote airports, located in ‘Remote Australia’ and ‘Very Remote Australia’ and facilitating RPT, general aviation and charters.

Australia’s aviation industry lacks an official classification system that encapsulates both domestic and international airports. The AAA’s airport categories, which are not officially implemented in the country’s aviation sector, do not clearly define the roles, functions and characteristics of airports. This gap signals the need for a classification system that comprehensively considers a range of airport attributes and the unique context of Australia’s aviation sector. The following section develops such a classification system based on an analytical discussion of the airport classifications outlined above.

5. Developing a Classification System for Australian Airports

Australia’s international airport classification only considers facilities and services related to overseas passengers at these airports. Meanwhile, the recently introduced (and now repealed) security classification employs risk-based criteria to evaluate the risk level in the operational environment of airports. The latter system is more comprehensive in classification criteria and applies to both domestic and international airports. The AAA utilises three criteria in categorising their member airports, namely airport location (in a capital city or a regional area), airport governance (managed and operated by a private organisation, a local government or the Federal Government) and airport ownership (private or public).

Notably, unlike the rest of the world, Australian airport classifications—including official ones and the unofficial system employed by the AAA—do not incorporate passenger-related measurements. However, passenger volume is arguably an essential criterion for classifying airports in Australia, given that several airports normally categorised as ‘regional airports’ by the AAA still service a relatively large volume of passengers, thus playing a significant role in the Australian aviation industry. In 2018–19, Gold Coast Airport and Cairns Airport were Australia’s sixth and seventh busiest airports, servicing more passengers than three out of the eight airports categorised by the AAA as ‘Tier 1 Capital City Airports’ [41]. Yet, under the AAA’s categorisation system, these airports would be considered ‘regional airports’ due to their location outside their state’s capital city, Brisbane. However, this category would inaccurately reflect the role and function of these airports as the sixth and seventh busiest airports in Australia.

Privatised airports in Australia are often collectively referred to ‘major airports’ (e.g., [42,43]) (21 of the federally owned airports in Australia are ‘privatised’ under the Airports Act 1996 [44]). Through this arrangement, these airports are managed and operated by private organisations). However, not all of these ‘major airports’ serve a large number of passengers [41], with privatised airports comprising only 11 of the country’s 20 busiest airports in 2023–24 [45]; as such, simply referring to privatised airports as ‘major airports’ is not an accurate reflection of the actual passenger volume of these airports. This approach could create a public misconception that all privatised airports play a significant role in the country’s aviation sector regarding passenger volume.

The AAA’s seven-tiered system categorises its member airports by the following five factors related to airport characteristics:

• Geographical location (e.g., capital city, non-capital city, regional area or remote community);
• Operational scope (i.e., whether the airport primarily serves domestic or international flights);
• Passenger volume;
• Availability of direct interstate flights;
• Facilitation of RPT services.

Although this classification framework appears comprehensive concerning the criteria considered, the AAA has not provided an exhaustive exposition for each airport category. Consequently, the lack of detailed elaboration may result in diverse interpretations of the seven-tiered categorisation among industry stakeholders.

The proposed definition of RRR airports by Donehue and Baker [38] offers a valuable framework for categorising the diverse range of airports in non-metropolitan Australia. Such a classification is necessary given the significant variations in their roles, functions, and attributes. They utilised the ASGC Remoteness Structure to categorise airports outside major urban centres into regional, rural, and remote airports. This approach adeptly incorporates the contextual nuances of these airports, acknowledging that their characteristics can markedly differ based on the level of remoteness. Moreover, the ASGC Remoteness Structure also delineates the ‘Major Cities of Australia’ category, encompassing capital cities and significant regional centres. This classification is particularly pertinent for major airports outside capital cities, as it enables their placement based on their location within a major urban centre.

6. Airport Tiers: A Proposed Airport Classification System for Australia

The authors have developed a conceptual classification encompassing four distinct categories for Australian airports, drawing on the above discussion on airport classification practices worldwide and a comprehensive understanding of Australian airport attributes. The classification, which employs the approach of combining multiple indicators related to airport properties and geographical factors [4], defines the role, function and characteristics of all Australian airports using four criteria: (1) location, (2) governance, (3) network function and (4) passenger profile.

While existing airport classification systems provide useful foundations, they vary in their focus on operational, spatial and institutional characteristics. The criterion related to passenger numbers, such as those in the United States, Europe and China, offers quantifiable thresholds but may prioritise volume over context. This approach can obscure the unique roles of regional or remote airports, which may be critical to network connectivity and regional sustainability despite relatively low traffic. Therefore, other relevant criteria are required. The governance criterion reflects the regulatory and ownership structures shaping airport management. Australia’s privatisation of airports, which resembles models in the United States and the United Kingdom, has shaped several airports and, as such, should be reflected in the classification. Meanwhile, the network function of airports, including hub-versus-spoke models or role-based typologies, allows the nuanced nature of airports’ activities and operations to be captured. In Australia, many regional airports serve diverse roles—from emergency services to pilot training to FIFO operations—that form the broader ‘general aviation’ activities.

The proposed airport classification combines structural attributes (governance and passenger profile) with contextual factors (location and network function), aiming to reflect not only what an airport is but also what it does, and for whom. This integrated approach recognises the differentiated nature of airports across Australia’s vast and varied landscape.

The classification is based on a ‘tier’ system with four tiers. The notion of ‘tier’ within the proposed airport classification model finds its foundation in the definition of “one of several layers or levels” [46]. Considering the wide-ranging variations in airports’ nature, location, function and operation, it is desirable to categorise them into distinct ‘tiers’ based on shared criteria, enabling their differentiation across various levels. The term ‘tier’ has also been widely used in the aviation industry and the literature. For instance, the AAA’s classification system for its member airports is based on seven tiers.

Additionally, de Neufville [47] employs the term to describe airports such as Memphis and Louisville as ‘second-tier airports’. Similarly, Grubesic et al. [48] offer a tier-based classification for airports worldwide, considering factors such as traffic flow and dominance over other airports, with Tier 1 airports exerting the highest influence over their counterparts. These different usages of ‘tier’ exemplify the term’s utility in facilitating a coherent approach to comprehending the diverse airport landscape. The four airport categories within the proposed classification are First-Tier Airports, Second-Tier Airports, Third-Tier Airports and Fourth-Tier Airports.

6.1. First-Tier Airports

First-Tier Airports, having been privatised through the Airports Act 1996, currently operate under the management of private entities. Positioned within the confines of a state/territory’s capital city, these airports fall within the ‘Major Cities of Australia’ zone of the ASGC Remoteness Structure (as depicted in Figure 2). Possessing pivotal significance, these airports play a paramount role in facilitating the seamless movement of both passengers and freight, serving as central hubs for multiple airlines. These airports also fulfil the vital function of being the principal international gateways for their respective state/territory. As primary facilitators of air travel domestically and internationally, First-Tier Airports command the highest proportion of passengers served amongst all airports within their respective state/territory.

6.2. Second-Tier Airports

Second-Tier Airports are located in major regional cities within the boundaries of ‘Inner Regional Australia’ in the ASGC Remoteness Structure. These airports, which may fall under the management of private entities or local governments, play a pivotal role in facilitating the movement of passengers and freight. Serving as prominent hubs for some airlines, Second-Tier Airports not only cater to a substantial portion of passengers relative to all airports within their respective state/territory but also may serve international flights. Owing to the array of on-site services, these airports can serve as alternate landing venues for First-Tier Airports in aircraft congestion or adverse weather conditions. The flexibility provided by Second-Tier Airports enhances the overall efficiency and reliability of air travel throughout the country.

6.3. Third-Tier Airports

Third-Tier Airports, located in regional areas within either the ‘Inner Regional Australia’ or ‘Outer Regional Australia’ zone of the ASGC Remoteness Structure, are owned and managed by local councils—with a few exceptions. Functioning as ‘spokes’ for both First-Tier and Second-Tier airports, these airports primarily facilitate domestic flights and cater to a relatively limited number of passengers. Depending on the scope of available facilities, Third-Tier Airports can also act as reliever airports for their higher-tier counterparts and facilitate a wide range of general aviation activities. In the Australian context, these airports play a vital role in connecting regional communities with capital cities and major regional centres, mitigating the challenges posed by ‘the enormous distances that often exist between … towns and cities’ in Australia [38]. Third-Tier Airports contribute significantly to fostering connectivity and accessibility within the country’s regional landscapes.

6.4. Fourth-Tier Airports

Fourth-Tier Airports predominantly comprise airports in communities located within the ‘Remote Australia’ or ‘Very Remote Australia’ classification in the ASGC Remoteness Structure. Similarly to Third-Tier Airports, most of these airports are owned and managed by local governments. Operating primarily to facilitate general aviation activities, Fourth-Tier Airports serve as key facilitators of pilot training, aerial work (e.g., aerial photography and agriculture), emergency medical services, and recreational flying pursuits. Given their remote locations and the corresponding constraints, Fourth-Tier Airports typically offer a relatively limited range of facilities, restricting access primarily to smaller aircraft compared to higher-tier airports. As a result, RPT and chartered flights servicing Fourth-Tier Airports may be available but remain limited in frequency. Nevertheless, Fourth-Tier Airports play an indispensable role in supporting aviation activities within their respective remote communities, fostering crucial services and contributing to the overall connectivity of such isolated regions.

6.5. Exclusion of Freight Dimension

The proposed classification excludes the freight aspect of airport operations, an important activity for many airports. The discussion below outlines the rationale behind this omission, which should be recognised as a potential limitation of the framework’s applicability.

Despite their smaller size, remote location, and limited passenger traffic, certain Australian airports handle substantial volumes of valuable freight. Toowoomba Wellcamp Airport is an exemplary illustration. Situated in the agricultural region of Toowoomba, this Third-Tier Airport serves as more than just a passenger facility; it focuses on fostering robust freight activities for the region. The airport was strategically built as ‘the only regional airport in Australia truly focused on growing a strong freight airline base rather than simply a passenger service facility’ [49]. As the state of Queensland’s sole airport with a dedicated 747-8F international freighter service, it has facilitated weekly international cargo flights since 2016 [50]. These flights transport agricultural products to Hong Kong, a gateway to the broader markets of China.

Meanwhile, certain major Australian airports within capital cities, which service substantial passenger volumes, handle minimal quantities of high-value freight and undertake limited freight operations. According to the Bureau of Infrastructure and Transport Research Economics BITRE [51], in 2018/19, three First-Tier Airports, namely Darwin, Canberra and Hobart airports, processed a relatively limited international freight volume of 475, 83 and 0 tonnes, respectively. However, they each served between two and three million total passengers. In contrast, although Toowoomba Wellcamp Airport, a Third-Tier Airport, serviced 110,000 passengers, its international freight totalled 1213 tonnes in the same period—a notably larger volume than that processed by the three First-Tier Airports mentioned here. These statistics portray the diversity in freight operations amongst Australian airports. Despite serving many passengers, higher-tier airports may not exhibit substantial freight activities. Conversely, lower-tier airports could surpass higher-tier airports in terms of freight handling. These characteristics underscore the impracticality of incorporating freight volume as a criterion for the proposed Australian airport classification. Therefore, future studies could develop a classification based on freight characteristics of Australian airports, expanding on the system proposed by Mayer [9] and reflecting the nuances of freight activities across Australian airports.

In Australia, freight activities are critical to many regional airports, particularly in supporting local industries and enabling remote community access to goods and services [52]. However, this classification framework prioritises indicators that apply consistently across the full range of Australian airports. Freight volumes are highly variable, often airport-specific, and not systematically reported across all airports, making them less suitable as a criterion in the proposed categorisation. Nevertheless, freight activities could form the basis for a future extension of the proposed classification or the development of an alternative categorisation based primarily or entirely on freight activities.

A summary of the proposed classification system is outlined in

Table 5. Proposed classification for Australian airports. Source: Authors.

Location	Governance	Network Function	Passenger Profile
First-Tier Airport
Capital city of a state/territory	Privatised	Main international gateway for the state/territory Key hub for multiple airlines Serve the highest passenger proportion amongst all airports in the state/territory	Domestic and international passengers
Second-Tier Airport
Major regional city or centre	Privatised or owned and managed by a local government agency	Hub for some airlines Spoke and reliever airport for First-Tier Airports Serve a large proportion of passengers in the state/territory	Domestic and international passengers Lower proportion of international passengers than First-Tier Airports
Third-Tier Airport
Regional city or town	Most are owned and managed by a local government agency	Spoke and reliever airport for higher-tier airports Connects regional communities with capital cities Facilitates general aviation activities	Only domestic passengers
Fourth-Tier Airport
Remote communities	Most are owned and managed by a local government agency	Primarily facilitate general aviation activities May occasionally service commercial flights	Only domestic passengers and in limited numbers

.

6.6. Application to Australian Airports

Figure 3 provides a broad yet non-exhaustive list of Australian airports (represented by their International Air Transport Association (IATA) codes) categorised across the four tiers under the proposed classification system. All First-Tier Airports are fully listed, while airports in other tiers are selectively included. The figure also identifies selected airports exhibiting overlaps between adjacent tiers.

Table 6. Full names of the airports listed in Figure 3.

IATA Code	Airport
First Tier
SYD	Sydney Kingsford Smith Airport
MEL	Melbourne Tullamarine Airport
BNE	Brisbane Airport
PER	Perth Airport
ADL	Adelaide Airport
DRW	Darwin International Airport
CBR	Canberra Airport
HBA	Hobart International Airport
First/Second Tier
MCY	Sunshine Coast Airport
NTL	Newcastle Airport
CNS	Cairns Airport
Second Tier
OOL	Gold Coast Airport
AVV	Avalon Airport
MKY	Mackay Airport
ROK	Rockhampton Airport
TSV	Townsville Airport
LST	Launceston Airport
Second/Third Tier
BNK	Ballina Byron Gateway Airport
CFS	Coffs Harbour Airport
PQQ	Port Macquarie Airport
TMW	Tamworth Airport
Third Tier
ABX	Albury Airport
MQL	Mildura Airport
PLO	Port Lincoln Airport
GET	Geraldton Airport
BME	Broome International Airport
KGI	Kalgoorlie-Boulder Airport
ARM	Armidale Airport
Third/Fourth Tier
PUG	Port Augusta Airport
KNX	Kununurra Airport
MOV	Moranbah Airport
NAA	Narrabri Airport
Fourth Tier
ISA	Mount Isa Airport
CPD	Coober Pedy Airport
LRE	Longreach Airport
PBO	Paraburdoo Airport
BCI	Barcaldine Airport
NAA	Narrabri Airport
DRB	Derby Airport
BRK	Bourke Airport

provides the full names of the airports shown in Figure 3.

Table 7. Application of the proposed classification to selected Australian airports.

Airport (IATA Code)	Location, State	Tier Attributes
First-Tier Airport
Sydney Kingsford Smith Airport (SYD)	Sydney, New South Wales	Capital City Location: The airport is located in Sydney, the capital city of the state of New South Wales, and the ‘Major Cities of Australia’ zone [53]. Significant Passenger Volume: The airport is Australia’s busiest airport, servicing a total of 41.5 million passengers in 2024 [45]. The airport handles a substantial share of passengers at both the state and national levels. In comparison, Newcastle Airport—the second busiest in the state—served 1.2 million passengers, while Melbourne Airport—the second busiest in the country—handled 35.5 million, both significantly lower than Sydney Kingsford Smith Airport’s traffic in 2024 [45]. International Gateway: In 2024, 40% of the airport’s passengers are international passengers [45]. It plays a pivotal role as the primary international gateway for both the state and Australia. Privatised: The airport has been operated by Sydney Airport Corporation Limited since its privatisation in 2002. Airline Hub: The airport serves as an operational hub for Qantas Airways and a transit hub between regional New South Wales, other Australian cities and other countries. It is also a strategic hub for major domestic airlines, including Virgin Australia and Jetstar Airways [54].
Second-Tier Airport
Gold Coast Airport (OOL)	Gold Coast, Queensland	Location in a Major City and Mega Region: The airport is located across the City of Gold Coast and Tweed Shire within the ‘Major Cities of Australia’ zone [53]. The City of Gold Coast, which receives the majority of the airport’s passenger traffic [55], is a major regional city located in proximity to Brisbane, the capital city of the state of Queensland. The city is also part of the ‘200 km city’, a mega-region centred around Brisbane [56]. Significant Passenger Volume: In 2024, the airport was Australia’s sixth busiest airport, serving 6.2 million passengers [45]. As the second busiest airport in the state behind Brisbane Airport, which served 23.3 million passengers in 2024 [45], Gold Coast Airport is an important hub connecting regional communities in South East Queensland and Northern New South Wales with major Australian Cities and a few countries, including New Zealand, the United States and Canada [57,58]. The recently completed expansion of the airport’s southern terminal has also increased the airport’s capacity to handle passengers, expected to grow to 13 million by 2044 [58]. Hub for Airlines: Domestically, the airport serves as a key spoke airport for Qantas Airways, Jetstar Airways and Virgin Australia, with daily flights to several First-Tier Airports. Low International Passenger Proportion: While the airport services international passengers, its share of such passengers (10% in 2024) is significantly lower than that of First-Tier Airports. For example, Sydney Kingsford Smith Airport, Melbourne Airport, and Brisbane Airport recorded international passenger proportions of 40%, 32%, and 26%, respectively, in the same year [45]. Nevertheless, international travellers are a notable presence in the airport’s passenger profile. Before the COVID-19 pandemic, the airport operated several direct international flights to other destinations, including Japan, Hong Kong, Singapore and Fiji [59]. In 2018–19, international flights accounted for 15% of the airport’s total passenger volume (6.4 million) [45]. Privatised: In 1998, the airport was privatised and its operating rights were transferred to Queensland Airports Limited. Diversion Destination for First-Tier Airport: While the airport does not officially function as a reliever airport, it has served as a diversion destination for flights bound for Brisbane Airport in events of severe weather or runway closures or aircraft [60,61].
Third-Tier Airports
Albury Airport (ABX)	Albury, New South Wales	Regional City Location: The airport is located in Albury, a city adjacent to the state border of New South Wales and Victoria. Owned and operated by Albury City Council, the airport serves the Albury-Wodonga region, which spans the state border and falls within ‘Inner Regional Australia’ [53]. Spoke Function: The airport connects residents of the region to Sydney, Melbourne and Brisbane. Thus, it serves only domestic flights and operates as a spoke airport for First-Tier Airports, servicing approximately 276,000 passengers in 2023–24 [45]. Facilitates General Aviation: The airport plays an important role in facilitating general aviation activities, servicing 32,700 general aviation aircraft movements in 2016–17. This figure is expected to steadily increase to 41,500 by 2031–32 [62].
Fourth-Tier Airport
Mount Isa Airport (ISA)	Mount Isa, Queensland	Remote City Location: The airport is situated in Mount Isa, a remote city in North West Queensland within ‘Remote Australia’ [53]. Limited Commercial Flights: According to Queensland Airports Limited [63], which has operated the airport since 2005, more than 82% of the airport’s passengers are attributable to chartered flights bringing in fly-in fly-out (FIFO) workers. Nonetheless, the airport facilitates RPT flights to Brisbane and other major cities in the state, recording 232,000 domestic RPT passengers in 2023–24 [45]. Facilitates General Aviation: With dedicated general aviation facilities, the airport enables general aviation activities encompassing helicopter operations, flight training and aerial surveying conducted by several businesses [64].

applies the classification to selected Australian airports, elaborating on one airport per tier.

To highlight the shortcomings of how Australian airports are currently categorised, Sydney Kingsford Smith Airport, Gold Coast Airport and Mount Isa Airport, due to their privatised nature, would all be referred to as ‘major airports’. Such a perspective does not accurately account for the airports’ vastly different attributes, as illustrated in Table 6. Nevertheless, certain airports, due to their distinct characteristics, may overlap between two adjacent tiers, as illustrated in

Table 8. Selected airports exhibiting overlaps between adjacent tiers of the proposed classification system. Source: Authors.

Airport (IATA Code)	Location (City, State)	Higher Tier Attributes	Lower Tier Attributes
First-Tier/Second-Tier Airport
Newcastle Airport (NTL)	Newcastle, New South Wales	Newcastle’s Close Relationship to Sydney: The airport serves Newcastle, a city situated within ‘Major Cities of Australia’ [53] and in the proposed ‘Six Cities Region’ centred around Greater Sydney [65] and its surroundings. Significant Passenger Volume: As the second busiest airport in the state and the fifteenth busiest airport nationally, the airport served 1.2 million domestic passengers in 2024 [45]. Robust Links to Capital Cities, Regional Cities and Remote Towns: The airport provides RPT flights to ten destinations, including capital cities, regional cities and remote towns nationwide. With frequent daily flights to First-Tier Airports and Second-Tier Airports and weekly flights to Third- and Fourth-Tier Airports, Newcastle Airport functions as a key spoke airport in the national flight network. Increasing Focus on International Flights: With frequent daily flights to Brisbane and Melbourne Airports—where passengers can connect to international services—the airport has been actively positioning itself as an alternative to Sydney Kingsford Smith Airport, which offers limited accessibility to regional communities. Its long-term vision includes offering “direct international flights to key trading and tourism destinations” by 2036, supported by ongoing investment in a new international terminal [66] (p. 15).	Non-Capital City Location: The airport is located in ‘Inner Regional Australia’, and Newcastle is not the capital city of New South Wales. Public Ownership: The airport is owned and operated by Newcastle Airport Pty Limited, a joint venture between the City of Newcastle and Port Stephens Council. No International Flights: Despite its emphasis on international connections for passengers, the airport currently facilitates only domestic flights, aligning it with the Third Tier.
Second-Tier/Third-Tier Airport
Ballina Byron Gateway Airport (BNK)	Ballina, New South Wales	Location in Regional City: The airport is situated in Northern New South Wales, within Inner Regional Australia. It serves Ballina, Byron Bay—a major tourism destination—and other surrounding cities and towns. Significant Passenger Volume: With approximately 628,000 domestic passengers served in 2024, the airport is the seventeenth busiest airport in Australia and the third busiest airport in the state (or fourth if counting Gold Coast Airport) [45]. Spoke for First-Tier Airports: The airport offers daily RPT services to First-Tier Airports, including Sydney Kingsford Smith Airport and Melbourne Airport.	Public Ownership: Ballina Byron Gateway Airport is owned and operated by Ballina Shire Council. Serves Only Domestic Flights: The airport facilitates only domestic flights, aligning it with the Third Tier. Facilitates General Aviation: The airport offers facilities for multiple general aviation businesses, including hangars, aircraft maintenance areas, a clubhouse and office spaces, fostering a vibrant aviation community [67].
Third-Tier/Fourth-Tier Airport
Port Augusta Airport (PUG)	Port Augusta, South Australia	Location in Regional Town: The airport is situated in Port Augusta, which lies within ‘Outer Regional Australia’ [53]. Emergency Services Hub: Since 2001, the airport has been a major base for the Royal Flying Doctor Service (RFDS) (The RFDS is Australia’s leading nonprofit aeromedical organisation, delivering emergency and primary healthcare services to rural and remote communities across the country) [68]. Its significance as an emergency services hub effectively positions it at a higher Tier. Facilitates General Aviation: Port Augusta Airport hosts the Port Augusta Aero Club and a range of general aviation facilities. Between 2015 and 2035, the airport’s annual general aviation aircraft movements are expected to grow from 5427 to up to 9802. The robust general aviation activities at the airport suggest placement at a higher Tier.	Proximity to Remote Communities: Port Augusta lies on the edge of the Outer Regional Australia zone and is bordered by ‘Remote Australia’ and ‘Very Remote Australia’ at distances of approximately 12 km and 70 km, respectively, to the north, northeast, east, and southeast [53]. The proximity of the airport to remote communities aligns with the Fourth Tier’s location criterion. No Commercial Flights: The airport currently services no RPT flights. The airport handles around 16,000 passengers via charters. These passengers are FIFO workers for the mining industry across the north of the state [69].

.

Airports in the overlapping areas between the proposed tiers, particularly between the first and second tiers and between the second and third tiers, offer the opportunity to prevent or mitigate the encroachment of incompatible developments around airports—such as tall structures and residential development. Government agencies can employ the proposed classification to identify airports with robust potential for future growth, development and expansion. This identification can assist in proactive land-use planning around these airports, allowing authorities to prohibit incompatible uses or reduce their intensity through mechanisms such as zoning regulations or land protection strategies.

7. Contribution to Sustainability

The proposed airport classification can help government agencies make strategic planning decisions that promote economic, social and environmental sustainability.

Table 9. The potential sustainability contribution of the proposed Australian airport classification to government decision-making.

Contribution	Explanation	Examples
Economic Sustainability
Efficient Resource Allocation	The distinct categorisation of airports enables national and state/territory government agencies to prioritise investments in infrastructure and services based on the specific needs of each tier. For instance, First-Tier and Second-Tier Airports may require more funding towards transport infrastructure to support their large number of passengers, whereas Third- and Fourth-Tier Airports may necessitate subsidies for emergency medical services.	Melbourne Airport, as a First-Tier Airport, is one of the busiest airports in the country. To support the airport’s projected growth, a Melbourne Airport Rail project, expected to be completed in 2030, will connect the airport to the regional and metropolitan train network [72]. Under the 2025–27 Regional Airports Development Scheme, the Western Australian Government is seeking grant applications for projects enhancing the state’s regional air services and safety. A major project supported in a previous round of the program involves upgrading of regional airstrips in Indigenous communities to enable more efficient emergency evacuations by the RFDS [73].
Regional Economic Development	The classification can assist government agencies in identifying potential airports with untapped potential for regional economic development through trade or tourism. For example, Second-Tier and Third-Tier Airports, with their strong linkages with capital cities, could be strategically marketed as gateways to surrounding natural attractions, boosting tourism and retail activities.	In late 2023, Mackay Airport established a partnership with Harrup Park, a local sporting club, to attract major sporting events and tourists to Mackay. This initiative seeks to capitalise on the airport’s recently expanded flight routes and the host region’s rich availability of sporting facilities and nature attractions [74].
Environmental Sustainability
Land Use Efficiency	The classification can be used to identify and preserve key areas for biodiversity protection or productive farmland around Third- and Fourth-Tier Airports or to create business parks within or around First- and Second-Tier Airports.	Leigh Creek Airport is a Fourth-Tier Airport located in the remote town of Leigh Creek, approximately 500 kilometres north of Adelaide, the capital of South Australia. The airport lies near Aroona Sanctuary, a legally protected nature reserve under state legislation [75]. With a resort and a town in its catchment, the airport can also be promoted as a base for chartered flights supporting scientific research and tourism, thus contributing to the conservation efforts linked to the sanctuary. In July 2024, MAB Corporation launched Haystone Business Park, a 38-hectare precinct to house warehouses and manufacturing facilities that benefit from the proximity to Melbourne Airport [76].
Tailored Environmental Initiatives	Lower-tier airports could serve as testing grounds for environmental initiatives with high potential impact, such as trialling new solar technologies at a Fourth-Tier Airport that benefits from year-round solar access.	To capitalise on the local availability of feedstock, Toowoomba Wellcamp Airport is developing a Sustainable Aviation Fuel facility in partnership with Boeing [77]. Gold Coast Airport is trialing autonomous shuttles to reduce the airport’s environmental footprint. It is also transitioning fleets to low- to zero-emission technologies as part of its Net Zero targets [58]. These environmental initiatives represent potential areas for collaborative research and development between the airport operators and external agencies.
Social Sustainability
Development Equity	The classification system can assist in advocating for more equitable resource distribution, where lower-tier airports are not overlooked in favour of higher-tier airports.	The Australian Government’s Regional Airports Program and Remote Airstrip Upgrade Program are national competitive grant initiatives with the intention to support regional and remote airports [78]. As such, the proposed classification’s criteria for Third-Tier and Fourth-Tier Airports can assist the programs in identifying eligible airports.
Essential Services	Lower-tier airports, particularly those in the Fourth Tier, play a critical role in providing healthcare and supplies to remote communities. The classification can be used to highlight these airports’ social functions to ensure ongoing support from government agencies and the private sector.	Mildura Regional Airport, a Third-Tier Airport, receives 10 RFDS flights daily, emphasising the airport’s important role in facilitating healthcare services for residents of Mildura [79].

demonstrates how the classification could enhance government decision-making concerning airports in relation to the three pillars of sustainability: economy, environment and society [70,71].

8. Conclusions

Airports vary significantly in purpose, scale, land use, activities and relationships with their surroundings and host region and country. Agencies worldwide classify airports for decision-making purposes. However, there is no standardised classification of airports globally. Similarly, Australia lacks a comprehensive airport classification that considers domestic and international airports and captures the manifold characteristics and diverse contexts of airports. This paper has developed a conceptual classification for Australian airports to address this gap. Integrating indicators related to airport properties and geographical factors, the tier-based classification defines Australian airport roles, functions and characteristics based on four criteria: location, governance, network function and passenger profile.

The proposed classification has several potential real-world applications and benefits. Allowing an airport’s role and characteristics to be clearly defined can assist national, state and local governments in strategic planning and decision-making for and around airports, including land use planning and infrastructure planning and funding. On the regulatory side, by distinguishing airports by their internal and external characteristics, the Federal Government can employ the classification to determine the applicable standards and regulations for all airports concerning such matters as safety, operation and development controls. Notably, the classification can assist government agencies in their decision-making towards more sustainable outcomes. For instance, recognising the important regional service role of airports in the second and third tiers could support more targeted investment in these airports and their associated infrastructure, while designation in an overlap between two adjacent tiers may imply the need for stricter land use controls to manage potential urban encroachment. Aligning planning and investment decisions with an airport’s tier can help prioritise sustainability goals in a more context-sensitive and efficient manner.

The conceptual classification also has potential applicability to airports in other countries. However, as countries vary in geographical contexts, the specific nature, roles and characteristics of airports outside Australia differ significantly from those of Australian airports. As such, future comparative research could investigate the characteristics of airports in another country, the findings of which can be used to revise the proposed classification by adjusting the specifics of each criterion and adding or reducing the number of tiers. Future studies could also investigate the relationship between the proposed airport tiers and the existing tier-based city classification systems. Since the proposed classification does not account for freight activities, future research on Australian airport classification could focus on developing a system that explicitly categorises airports based on freight volume and characteristics.

This paper has outlined key findings from the initial qualitative phase of the authors’ Australian airport classification study, highlighting limitations associated with the existing classification and proposing a new framework based on a literature review and policy analysis. The future plan for this study involves further development of the proposed four-tiered Australian airport classification, including quantitative validation and application to categorise all Australian airports.