Key Enablers for the Evolution of Aerospace Ecosystems

The aerospace industry is experiencing an unprecedented scenario. The air travel drifted from years of constant growth and positive expectations to a place where the uncertainty is the most predominant distinctive. Consequently, the aerospace ecosystem needs to adapt to cope with challenges never faced before. Understanding the evolution of the aerospace ecosystem is thus essential to foster its progression. This research aims at the identification and categorisation of key enablers that have been linked to the growth of aerospace ecosystems. To this extent, key enablers are first identified and then categorised using interpretive structural modelling (ISM) and cross-impact matrix multiplication applied to classification (MICMAC) methodologies. An analysis is elaborated for a developed aerospace ecosystem, the United Kingdom, and an emergent aerospace ecosystem, Mexico. Results evidence a contrasting categorisation of key enablers among both ecosystems. On the other hand, the automotive ecosystem and geopolitical factors are considered as underpinning enablers for both aerospace ecosystems evolution.


INTRODUCTION
Since February 2020, the world has been facing an unprecedented public health emergency driven by the coronavirus (COVID-19), causing long-lasting consequences among industrial ecosystems of different nature. Particularly, the aerospace industry is experiencing an unprecedented scenario. The air travel drifted from years of constant growth and positive expectations to a place where the uncertainty is the most predominant distinctive. Abrupt reduction on passenger travels and deferred customers deliveries are among the primary short-term consequences. For instance, in April 2020, airlines around the world reported a drop in air travel of around 96% (Wallace 2020). Furthermore, the International Air Transport Association (IATA) forecasts for 2020 a drop in global airline passenger revenues by around 55% (equivalent to more than US$ 300 billion), compared to 2019 (IATA 2020). The mid and long-term consequences are still unmeasurable. According to Lineberger (2020), the production demand over the next two years is not expected to change because the budgets were already allocated. However, the main long-term impact will be a shortage in cash-flow, increased risk on critical program failure and a weakened supply chain driven by increased production challenges.

Supplier development programs
This factor refers to the creation and implementation of policies from either the government or the private sector, aiming at suppliers development. The UK government, in conjunction with the civil sector, has historically implemented strategies to enhance the supply chain of the aerospace sector. As a consequence, as in 2019, the supplier base of the UK aerospace ecosystem has grown to a level where around 90% of the + 3,000 aerospace companies located in the UK are micro-sized (less than 10 employees) suppliers (United Kingdom 2019b). The latest strategy was launched at the beginning of 2019, a new supply chain competitiveness programme aiming to help small and medium enterprises to become more productive and competitive (United Kingdom 2018).
Another example of supplier development programs is the creation of the AGP. Since its creation in 2010, the AGP has enabled the evolution of the aerospace sector by generating 45% turnover growth of its members and has helped more than 300 companies to achieve world-class levels through supply chain programmes (ADS Group 2019). In particular, as part of the AGP, the UK has developed policies mainly aimed at technology innovation on small and medium-sized enterprises (SMEs), through the National Aerospace Technology Exploitation Programme (NATEP).

Supporting organisations
Development of supporting organisations between private industries, academia and the government is another key enabler for evolution. The ADS Group, the AGP and the ATI are examples of such organisations.
The ADS Group, created in 2009, is a trading organisation aiming to represent and promote the UK aerospace, defence, security and resilience, and space sectors. As in 2019, the ADS Group represents more than 1,000 companies, in which around 950 are SMEs. Such companies provide more than 100,000 direct employees and nearly 4,000 apprentices to the aerospace sector (ADS Group 2019). The AGP, facilitated by the ADS Group, was formed in 2010, focused on creating a vision and strategies to secure the growth of the aerospace sector for the following decades. Reach for the Skies (AGP 2012), Lifting Off (HM Government 2013), Flying High (AGP 2014), and Means of Ascent (AGP 2016)  at Cranfield University aimed at collaboration between the industry and the academia; and the funding of aerospace-related scholarships (Rhodes and Brien 2017). The AGP enables the evolution of the UK aerospace ecosystem mainly by the identification of the growth inhibitors caused by the UK market failure. It encourages the companies, part of the UK aerospace ecosystem, to coexist and increase collaboration to tackle together growth inhibitors, increase exports and high-value jobs. Another way in which the AGP has enabled the aerospace ecosystem development is by helping with productivity improvement. According to AGP (2016), from 2010 to 2016, the UK aerospace manufacturing productivity increased by 39%. The increment has been driven mainly by generating new skills, the introduction of radical technologies and improved processes.
The ATI was established in 2013 to help the AGP technology strategy to boost the UK aerospace ecosystem as a world leader in technology and innovation by developing strategies and targeting investment (ATI 2018b). This institute has enabled the UK aerospace ecosystem by ensuring an annual investment from the civil and public sectors up to £ 300 million per year in technology until 2026 (ATI 2018a). In 2018, ATI portfolio embraced 214 projects, involving more than 200 companies, reaching a value of £ 2 billion. Besides, it supported the installation of the first Boeing manufacturing facility outside the USA and the Airbus wing integration centre in Filton. Within its main programmes are aircraft of the future, propulsion of the future, aerostructures of the future and smart, connected and more electric aircraft. Previous programmes are aiming to enable the aerospace ecosystem by focusing mainly on fuel efficiency, increased use of electricity and innovative manufacturing processes, such as additive manufacturing (ATI 2018a).

Investment in human capital development
There is robust historical evidence to claim that the development and success of industries based on science in a country is connected to the success of its scientific research (Broadberry and Leunig 2013). Evidence suggests that the leading position of the UK in the aerospace sector has been predominantly a result of the historical institutional expertise and extensive scientific research that has led to the human capital development (House of Commons 2017a). Creation of research centres to link academia and industry, like the ARC and the AIRC, and support of aerospace-related scholarships are examples of actions that have helped the human capital development in the UK.
Examples of activities that the AGP has implemented to enable the aerospace ecosystem are the funding of 500 Aerospace Engineering Master of Science (MSc) bursaries, helping to develop high-quality apprenticeships, the creation of an aerospace employer ownership pilot to cover opportunity areas in skills and the Aerospace Industrial Cadets Programme (AGP 2016).

Geopolitical factors
The aerospace industry is highly globalised and export-oriented and, therefore, so is the UK aerospace ecosystem. Indeed, this sector is unavoidably tied and benefits from geopolitical factors (House of Commons 2017a). In this study, geopolitical factors are considered as those influenced by the relationships with other countries, particularly in terms of trading.
As of 2019, 95% of the UK aerospace production is exported (ADS Group 2019). The UK, as a member of the World Trade Organisation (WTO), signed the Agreement on Trade in Civil Aircraft (ATCA). This trade agreement permits that all exports and imports of civil aerospace parts are exchanged duty-free within the EU and other 20 nations, such as the USA and China (WTO 2019).
In addition to the duty-free agreements, there are the bilateral safety agreements (BASA), which allow mutual airworthiness certification. The main benefit is that traded products require airworthiness certification only by one of the signatory countries (generally from the exporter/manufacturer). The UK, as a member of the European Aviation Safety Agency (EASA), has BASAs with Canada and the USA since 2011, and with Brazil since 2013 (EASA 2019).
Airworthiness certification agreements between the European Union Aviation Safety Agency (EASA) and the Federal Aviation Administration (FAA) have been slightly affected due to the Boeing 737 MAX accidents. This aircraft was grounded worldwide after two crashes caused multiple fatalities, the first one in October 2018 from Lion Air of Indonesia and the second one in March 2019 from Ethiopian Airlines. Evidence of the changes is that the EASA has stated that Boeing 737 MAX aircraft will not fly again European skies until this organism certificates all Boeing design changes, independently from the FAA certification (Konert 2019). However, although airworthiness certification agreements have not been drastically changed yet, a recent study suggests that they must be innovated after the Boeing 737 MAX crashes evidenced their obsoleteness. For instance, Sgobba (2019) indicated that airworthiness authorities should migrate from a rule-based to a risk-based certification process. The first one refers to rules based on the design standards, while the latter refer to rules based on the performance and outcome required.
As in April 2021, the fact that the UK has left the EU on January 31, 2020 (Brexit), geopolitical concerns are still present. However, according to McGuire (2017), the application of tariffs due to Brexit does not represent a potential risk to the UK manufacturing ecosystem, thanks to the fact that the UK, as a member of the WTO, has individually signed the ATCA. The biggest concern is the BASAs and the potential delays that could be caused by the new paperwork and bureaucracy requirements when crossing the border. It is still uncertain if the UK, as a member of the EASA, will still be beneficiated from the current BASAs (House of Commons 2018b). Conversely, international air services do represent potential risk because their governance depends on the Air Service Agreements (ASAs), which are independent of the WTO. Although the UK has ASAs individually with 111 countries, it also depends on ASAs signed between the EU and individual countries. Examples of the latter scenario include some of the UK major partners, such as the USA and Canada (House of Commons 2017b).

Research and development (R&D) public funding
Economic success in the UK is driven by R&D. Innovation is considered as the key enabler for booming the UK economic growth and productivity, and particularly in aerospace has evidenced substantial returns (ATI 2018b).
The UK aerospace ecosystem is highly dependent on R&D government expenditure. This sector receives around 12% of the manufacturing R&D budget (House of Commons 2018b). In the UK, public funding is generally granted to aerospace companies via ATI. Since 2014, this institution has targeted more than £ 1.95billion in funds of over 200 companies (ADS Group 2019).
Aircraft of the future, aerostructures of the future, propulsion of the future, smart, connected and more electric aircraft (ATI 2018a), and accelerating ambition (ATI 2019) are the latest strategies to promote technological development. Another example of public funding is the aerospace sector deal, launched in 2018. In this strategy, the UK government has designated £ 125 million for aerospace research and development (House of Commons 2017a).
The UK aerospace ecosystem has also been beneficiated from public funding coming from the EU (Butcher 2018; ADS Group 2017; House of Commons 2018b). For instance, the programme Horizon 2020 was developed to spread R&D grants over EU members through diverse industrial sectors. The UK is the second-largest beneficiary from this program, receiving annually 13.5% of the funding (House of Commons 2019). The UK aerospace ecosystem receives annually nearly £ 100 million from the Horizon 2020 programme (House of Commons 2018b). It is relevant to highlight that this particular funding coming from the EU is at risk due to Brexit. As in February 2020, the future of this funding is still uncertain.

Privatisation of aerospace companies
Although the government funding has been a determinant for the evolution of the UK aerospace sector, the privatisation of public companies has historically been also a key enabler (Broadberry and Leunig 2013;Garside 1998). During the last halfcentury, firms from the aerospace sector in the UK have fluctuated from being private to public and vice versa. In the 1970s, the nationalisation of aerospace manufacturing firms boomed mainly as a strategy to rescue them from collapsing (Broadberry and Leunig 2013). For instance, Rolls-Royce was nationalised in 1971, and British Aerospace (BAe) surged in 1977 from merging and nationalising British Aircraft Corporation (BAC) and Hawker Siddeley Aviation (HSA). A decade later, once both companies regain strength, they were privatised. Nowadays, the aerospace industry and airlines belong to the private sector.

Strategic alliances of manufacturing firms
Another key factor for the evolution and success of the UK aerospace ecosystem is the association and collaboration of firms not only at national level, but also with European manufacturers (Broadberry and Leunig 2013). Airbus is arguably the best example. It is now the second-largest aerospace company in the world, formed in 1970 by merging European manufacturers aiming at competing with Boeing. Examples of successful strategic alliances at a national level are the creation of BAE Systems in 1999 from merging BAe, and Marconi Electronic Systems; and the BAe, which surged in 1977 from merging BAC and HAS. Previously, BAC was originated from merging Vickers-Armstrongs, English Electric Aviation, Bristol Aircraft Limited and Hunting Aircraft Limited (Broadberry and Leunig 2013).

Other industrial ecosystems
The aim of this part of the research is the identification of other ecosystems that have endorsed the evolution of the UK aerospace ecosystem. Such industrial ecosystems, considered in this part of the research as key enablers, are part of the results from the quantitative analysis presented in the following chapters. From the evolution of the networks of developed aerospace ecosystems, popular products are identified. Popular products are those commodity codes (using the Standard International Trade Classification, SITC, revision 3), apart from the aerospace products, in which the UK has continuously demonstrated a revealed comparative advantage (RCA > 1) from 1992 to 2016. The full list of products is presented in Table 2. Here, codes are grouped in the following industrial ecosystems: automotive ecosystem (code 78), chemical ecosystem (codes 51, 52, 53, 55, 58, 59), machinery ecosystem (codes 71, 72 and 74), pharmaceutical and medicinal ecosystem (code 54), agricultural products ecosystem (codes 00 and 11) and nonagricultural products ecosystem (codes 87 and 89). The products classified by industrial ecosystems are presented and discussed with experts on the UK aerospace ecosystem. After a discussion about the influence of each industrial ecosystem on the growth of the UK aerospace ecosystem, it is decided to consider such industrial ecosystems as following: • Automotive ecosystem refers to the supply chain developed for the automotive manufacturing sector. The UK automotive ecosystem is considered as a key enabler for the UK exports of industrial goods (SMMT 2019) and a British success story (House of Commons 2019). As in 2018, the automotive industry accounted for 14.4% of all exported goods in the UK, positioning this sector as the UK largest exporter of goods (SMMT 2019).

•
Chemical ecosystem includes products such as dyeing, tanning and colouring materials, inorganic chemicals, perfume and cleaning preparations, and plastics in non-primary forms. The UK chemical ecosystem is one of the most successful in the world, and it is a key player in the supply chain of industries, such as the aerospace and automotive industry (House of Commons 2019).

•
Machinery ecosystem denotes to the manufacture of general industry machinery, machinery for specialised industries and power generating machinery.

•
Pharmaceutical and medicinal ecosystem comprise the capabilities to manufacture all pharmaceutical and medicinal products. The pharmaceutical ecosystem has been considered as one of the most successful manufacturing sectors in the UK, in conjunction with the aerospace sector (Kitson and Michie 2014).

•
Agricultural products ecosystem embraces the production of all animals and edible products.
• Nonagricultural products ecosystem refers mainly to the ecosystem required for the production of other goods not included within previous classifications (others apart from the automotive, chemical, machinery, pharmaceutical and medicinal and agricultural products ecosystems presented previously).
In this research, it is assumed that previous ecosystems have endorsed, to a certain extent, the evolution of the aerospace ecosystem in the UK. In particular, it is assumed that elements inherent to those industrial ecosystems, like the required infrastructure, manufacturing capabilities and the supplier base, have fostered the evolution of the aerospace ecosystem.

Key enablers for the development of the Mexican aerospace ecosystem
In this part of the research, the Mexican aerospace ecosystem is used as a case example of an emergent ecosystem.
The beginning of the aerospace industry in Mexico dates back to the early 1900s when, in 1915, an innovative propeller named Anahuac was designed and manufactured in this country (Navarrete 2011). However, along most of the last century, its aerospace ecosystem did not experience significant development. It was until the end of the 1900s and the beginning of 2000s when the government implemented policies to start attracting investment from foreign companies motivating them to relocate their facilities in Mexico. As in 2018, the Mexican aerospace ecosystem embraces more than 300 aerospace-related firms dedicated to production, maintenance, repair and operation (MRO) and research and development (R&D) activities (INEGI 2018;ProMexico 2017).
In Fig. 1, the evolution of the number of companies from 2006 to 2016 is presented by type: manufacturers, MRO and R&D.
In the eleven years, the number of companies triplicated. As evidenced, most of the companies belong to the manufacturing sector. The companies are concentrated predominantly close to the USA border, and are grouped in the following five clusters: • Baja California: it is dedicated to manufacturing processes outsourcing, precision machinery, electric and power systems, and hydraulic and interior systems. This cluster produces the most significant number of exports within the country. More than 70 international companies are represented, such as Honeywell Aerospace, UTC Aerospace Systems, Gulfstream, GKN Aerospace, Triumph Group, LMI Aerospace and Rockwell Collins (ProMexico 2017).
• Queretaro: within the main capabilities of this region are the assembly and manufacture of aeroplanes and helicopter parts, turbines, landing gear and MRO. It has been the region that has grown the most in the last decade, and currently holds the most significant number of R&D entities. It has Bombardier Aerospace and Airbus Helicopters as prime manufacturers; Safran Aircraft Engines, Safran Landing Systems, TechOps and ITP as MRO; Safran Aircraft Engines, Safran Landing Systems, Meggitt Aircraft Braking Systems and Aernnova as tier-1 firms and has more than 15 > tier-1 companies. It also has Horizontec, the only Mexican company that is currently developing, manufacturing and assembling light-sport and experimental aircraft (Torres et al. 2019). As in 2019, the Mexican aerospace ecosystem is considered as the 12th largest aerospace manufacturer in the world (FEMIA 2019). Since 2009, its aerospace ecosystem has experienced a 14% annual average growth (Muñoz-Sanchez et al. 2019). The development has been achieved to some extent by the enablers identified in this research, which are listed in Table 3. As elaborated for the UK aerospace ecosystem, key enablers for the Mexican aerospace ecosystem are identified through a quantitative analysis and a literature review nurtured and validated with experts. In regards to the literature review, key enablers comprise a summary of the ones suggested by recognised organisations and experts in the Mexican aerospace ecosystem. Since the Mexican manufacturing ecosystem is characterised for hosting foreign companies, the Mexican government has continuously promoted the Mexican aerospace ecosystem to attract investments. As part of the effort, recognised organisations have published official reports containing characteristics of the ecosystem and key enablers that have thrived its evolution. Examples of such organisations include ProMexico, a subdivision of the Ministry of Economy, the Mexican Federation of the Aerospace Industry (FEMIA), the National Centre for Aerospace Technologies (CENTA) and the National Council of Science and Technology (CONACYT). Hence, a summary of key enablers suggested by such recognised organisations is included in this research.
Similarly to the UK aerospace ecosystem analysis, the list of key enablers is divided into two categories: five key enablers from a literature review and three from quantitative analysis. A description of each key enabler is presented next.

Geopolitical factors
Mexico geographical location as a USA neighbour and trade agreements with this country are key enablers that have propelled its attractiveness to foreign manufacturing firms (Meraz-Rodríguez et al. 2019;Morsi et al. 2018;Padilla and Suarez 2018;Quesada et al. 2015). It is positioned as the 9th largest exporter and the 13th largest importer in the world. Thanks to duty-free trading agreements with 45 countries, 93% of imports to this country enter without tariffs (Geiger et al. 2016). It is part of the North American Free Trade Agreement (NAFTA) between Canada and the USA. The leading destinations of its exports are the USA (73%), Canada (5.2%) and Germany (2.1%). Most of its imports come from the USA (51%), China (15%) and Germany (4.2%). Mexico is the first destination of the USA exports (15%) and second in imports (14%), after China (22%) (OEC 2019). Regarding the aerospace ecosystem, around 80% of exports from this sector are sent to the USA, taking advantage of the BASA signed since 2007 (INEGI 2018). It is positioned as the 7th largest aerospace supplier of the USA (Padilla and Suarez 2018).

Labour: low cost and highly-qualified
Mexico economic condition, particularly the relatively low-cost wages compared to the USA, gives this country a comparative advantage to foreign companies when trying to access the USA market (Coffin 2013;Martínez-Romero 2013;Morsi et al. 2018;Trimble 2016). As in 2020, the minimum wage in Mexico per hour is US$ 0.82 (Mex$ 15.4) for most of the country, and US$1.23 (Mex$ 23.2) for regions bordering with the USA. Whereas in the USA, the federal minimum wage per hour is US$ 7.25. This economic condition promotes foreign companies to manufacture their products in Mexico and send such products to the USA.
In addition to the wages, nowadays, Mexican labour force is considered as highly-qualified (Coffin 2013;Padilla and Suarez 2018;ProMexico 2017). It is particularly strong in manufacturing capabilities, such as metal-mechanic processes needed for the automotive and aerospace sector (Padilla and Suarez 2018).

Investment in human capital development
In the last decades, the Mexican government has implemented public policies to improve labour skills aiming at enabling the aerospace ecosystem development (Padilla and Suarez 2018;ProMexico 2017). In the recent years, in regards to the number of engineers, Mexico has been considered the country with the highest number in Latin America, and it is positioned within the top ten in the world (Padilla and Suarez 2018).
The CONACYT, founded in 1970, is an example of a public organisation that has enabled human capital development. Since 1971, this organisation has provided more than 450 thousand science and technology-related scholarships (CONACYT 2018).
The motivation of the government catapulted in 2005 when Bombardier officialised its investment to start a manufacturing facility in Queretaro dedicated to the installation of sub-assembly systems, electrical harnesses and carbon fibre structures. To attend Bombardier requirements, the government opened a public university, Aeronautical University of Queretaro (UNAQ), located next to Bombardier facilities. The Mexican government claims that this educational institution promoted the attraction of new foreign investments and enabled the evolution of the aerospace ecosystem (Luna et al. 2018b;Luna-Ochoa et al. 2016;Meraz-Rodríguez et al. 2019;Muñoz-Sanchez et al. 2019). Nowadays, more than twenty educational institutions are offering specialised courses in this sector (ProMexico 2017).

Supporting organisations
Organisations part of the Mexican triple helix, as first proposed in the framework developed by Etzkowitz and Leydesdorff (1995), holding synergy from the academia, private and public sector have been considered as key enablers for the growth of the Mexican manufacturing ecosystem (Guerrero and Urbano 2017), and particularly for the emergence of the aerospace ecosystem (Coffin 2013;Morsi et al. 2018;ProMexico 2017). The CONACYT is an example of a public organisation aiming at developing enhancement policies and promoting technological innovation in this country. Thanks to this organisation, in 2018, the national budget for R&D has increased by 70% compared to the 2001-2006 period (figures for particular sectors are not available) (CONACYT 2018).
Another example is FEMIA. It is a nonprofit organisation established in 2007 between private industries and government aiming at the development of the aerospace ecosystem. This organisation represents more than 110 aerospace companies, including Airbus, Bombardier, General Electric and Safran group (FEMIA 2019). The FEMIA enables the aerospace ecosystem mainly by providing consulting services, such as support with the aerospace certification and the supplier base development.
The CENTA, founded in 2016, is the latest supporting organisation proposed by the FEMIA and developed by the CONACYT and the Ministry of Economy. Nowadays, it is the only R&D institution entirely devoted to the aerospace sector in Mexico (Muñoz-Sanchez et al. 2019). The CENTA enables the aerospace ecosystem in Mexico mainly by providing to the industry aerospace testing laboratories and support for product development. The development of an SME called Horizontec is an example of the efforts of the CENTA to enable the Mexican aerospace ecosystem. Horizontec is a Mexican company, developed in a joint venture with CENTA, capable of designing, manufacturing and testing light-sport aircraft (Torres et al. 2019).
ProMexico is an example of a public organisation developed in 2007 dedicated to attracting foreign investments for a wide range of business sectors (Ortiz et al. 2014). ProMexico promotes the strengths of the Mexican ecosystem and mainly aims to enable the aerospace ecosystem by attracting foreign direct investment. This organisation analyses the aerospace ecosystem, promotes its strengths, identifies opportunity areas and develops investment road maps (Padilla and Suarez 2018)

Foreign investment
The main economic activity of Mexico is the manufacturing industry, derived predominantly from foreign investments. The manufacturing sector represents around 18% of its gross domestic product (GDP) (Padilla and Suarez 2018). In 2019, Mexico was considered within the top ten in the world in terms of industry capabilities (such as industry size, growth, maturity, profit margin and labour cost). Particularly for the aerospace industry, it has been ranked as the number 35 in the world and second most attractive country for aerospace manufacturing investments in Latin America, just after Chile (PwC 2019). From 2007 until 2016, the Mexican aerospace ecosystem received US$ 3,285 million from foreign investment, where 47% came from the USA, 36% from Canada, 12% from France, 4% from Spain and the rest from other countries (INEGI 2018). According to ProMexico (2018), Mexico is the 3rd largest receiver of aerospace direct foreign investment in the world. As in 2016, it was the 12th largest exporter of aerospace products in the world, holding nearly 2% of world exports (INEGI 2018).

Other industrial ecosystems
Similarly to the UK aerospace ecosystem analysis presented previously, this part of the research aims at the identification of other ecosystems that have endorsed the evolution of the Mexican aerospace ecosystem. The full list of products is presented in Table 4.
Here, codes are grouped in the following industrial ecosystems: automotive ecosystem (code 78), machinery ecosystem (codes 71, 76 and 77), agricultural products ecosystem (codes 00, 05 and 11) and nonagricultural products ecosystem (codes 81 and 82). As elaborated during the UK aerospace ecosystem analysis, the products classified by industrial ecosystems are then presented and discussed with experts on the Mexican aerospace ecosystem. After a discussion about the influence of each industrial ecosystem on the growth of the aerospace ecosystem in Mexico, experts decided to exclude the machinery ecosystem as an enabler. Most of the experts suggested that the machinery ecosystem has not considerably influenced the growth of the aerospace ecosystem in this country. Among the main reasons expressed during the discussion is the fact that experts believe that the machinery ecosystem is more a consequence rather than a cause. Experts suggested that the evolution of other industrial ecosystems, such as the automotive ecosystem, have enabled the growth of the machinery ecosystem. Consequently, the discussion concluded that it should be included under the nonagricultural products ecosystem.
Thus, the industrial ecosystems considered as enablers in this part of the research are as follows: In this research, it is assumed that previous ecosystems have endorsed to a certain extent, the evolution of the aerospace ecosystem in Mexico. In particular, it is assumed that elements inherent to those industrial ecosystems, like the required infrastructure, manufacturing capabilities and the supplier base, have fostered the evolution of the aerospace ecosystem.
The next step is the categorisation of the key enablers using the ISM and MICMAC methodologies.

CATEGORISATION OF THE KEY ENABLERS USING ISM AND MICMAC METHODOLOGIES
The process for the categorisation of the key enablers using ISM and MICMAC is described in Fig. 2. Once the key enablers are identified and validated, the first step is the interaction with experts. In this step, the experts are asked to establish contextual relationships via a structural self-interaction matrix (SSIM). The next step is the elaboration of the initial reachability matrix (IRM). In this matrix, experts' opinions are converted into a binary matrix. Then, transitivity is checked, and a Final reachability matrix (FRM) is elaborated.
From the FRM, the driving and dependence power is calculated as part of the MICMAC analysis, and the cause-effect interactions are computed through the levels partition step. The next step is to portray the key enablers in a structural model.
To this aim, first a directed graph is developed. In this graph, each key factor is portrayed at a different level according to the levels partition from the previous step. Once the directed graph is developed, all the transitivity links are removed.
Finally, the ISM and MICMAC models are generated and validated. A detailed description of each step is presented next.

The categorisation of key enablers for the evolution of the UK aerospace ecosystem
The group of experts is selected based on their adherence to the UK aerospace ecosystem and their professional background. The selection criteria aimed to choose experts from both private and public sectors, with vast experience working in the UK aerospace ecosystem. Therefore, the selected group of participants consisted of four experts with more than ten years of working experience in the UK aerospace industry; three of them working in the private sector and one expert working for a public R&D institute (Table 5). Experts' opinions are gathered in a workshop developed during the UK National Manufacturing Debate 2019 hosted by Cranfield University. This is an annual event aiming at enabling continued and long-term growth for the manufacturing industry, by promoting networking and collaboration across manufacturing professionals from different sectors (more information can be found at https://www.cranfield.ac.uk/events/national-manufacturing-debate/national-manufacturing-debate). In the workshop, an explanation of the methodology and a description of each key factor is described to the experts. After a discussion, experts are asked to eliminate the proposed key enablers and to suggest any additional one. Finally, the list of key enablers is updated according to experts' suggestion.

Structural self-interaction matrix (SSIM)
The experts' opinion for the establishment of the cause-effect relationships via SSIM can be gathered mainly by consensus or individual opinion approaches. The main advantage of using the first approach is the collaboration across participants for the achievement of a mutual agreement by sharing diverse perspectives (particularly sharing different points of view that may not be evident for all participants). The main weakness of this approach is that as individuals' expertise, judgement and power to express its arguments can dominate others, it is impossible to assure the correctness of a consensus reached in a group discussion, as suggested by Schuman (2002). On the other hand, the main advantage of using individual opinions approach is the minimisation of the bias in a group discussion caused by an individual's power to express their arguments.
In this research, the individual opinion approach is selected, aiming at trying to reduce the bias that could be generated during a group discussion. To that end, each participant is requested to, using the symbols described in Table 6, individually fill in Table 7. For instance, considering that factor 2, supporting organisations, influences factor 10, machinery ecosystem, the symbol ▲ is used (in this case, factor x is factor 2 and factor y is factor 10). By using this symbol, it is assumed that factor 2 does not get affected by factor 10. A total of four SSIMs are generated.

Initial reachability matrix (IRM)
Subsequently, the IRM summarising independent opinions is elaborated. To this aim, each SSIM is converted into an IRM.
Thus, four IRM matrices are generated. Each IRM is produced by converting each SSIM into a binary matrix, according to the rules from Table 8. For instance, if factor 2 affects factor 10, but factor 10 does not affect factor 2, described by using ▲ in the cell (2,10), the value of cell (2,10) in the IRM is 1 and 0 for cell (10,2). As they are four participants, a value of 1 is assumed when two or more individual IRMs have a value of 1 and a value of 0 for all the others.
The final IRM is presented in Table 9. This table summarises the expert's opinion expressing pairwise relationships using binary language. A value of 1 indicates a causality relation, while a value 0 indicates no relationship between factors. For instance, cell (3,1) has a value of 0, while cell (1,3) has a value of 1. The former value indicates that factor 3 does not affect factor 1. The latter indicates that factor 1 causes factor 3. The next step is the elaboration of the FRM.

Final reachability matrix (FRM)
The FRM adds more cause-effect relations by adding transitivity to the final IRM (Table 9). In mathematics, transitivity between three elements exists when a mutual relationship is derived from one indirect connection. For instance, if x is related to y, and y is related to z; consequently x and z have a transitive relationship. Thus, the FRM for the UK aerospace ecosystem, presented in Table 10, is elaborated indicating transitivity relations with a 1*.

Levels partition
The next step is the partition of the FRM into different levels. A summary of the level partitions is presented in Table 11.

Interpretative structural modelling for the UK aerospace ecosystem
The next step is the development of the directed graphs by using the levels partitions from the previous step. The outcome of the level partition from the previous step resulted in a 6-level model. Each level contains all the factors indicated in Table 11. For instance, factors 5, 10 and 12 are categorised as level one. Thus, such factors are positioned at the top of the model. This level is characterised by having the factors that do not help to achieve any others. The next level has only one factor, number 6. Thus, it is positioned just below the top level. The process continues until the last level. The links between the factors are generated from all the 1 and 1* from the FRM. Finally, the ISM model, Fig. 3, is generated after removing the transitivity links and replacing numbers by statements.

A MICMAC analysis for the UK aerospace ecosystem
Within the MICMAC analysis, each factor is classified as autonomous, linkage, dependent or driver. Autonomous are those factors that are more disconnected, as they are considered to have the least influence to and from others. Factors are classified as linkage when any action related to them drives an effect on them and others. Dependent factors got the most influence from others, and driver factors are considered as the key enablers to other factors (Raj et al. 2008). Results are presented in Fig. 4.

Interpretation of results of the categorisation of the key enablers that have fostered the UK aerospace ecosystem evolution
The analysis resulted in a six level ISM model, where each level represents the hierarchy of the key enablers. The bottom level, level 6, according to Table 11, is considered as the base of the model. This level is characterised for having the key enablers that trigger all the others. Thus, according to the analysis elaborated in this research, geopolitical factors, the automotive ecosystem and nonagricultural products ecosystem are considered as the key triggers for the evolution of the UK aerospace ecosystem. Evidence suggests that the UK aerospace ecosystem is tied-up to the geopolitical factors (House of Commons 2017a), driven by free trade agreements with other nations, 95% of the UK aerospace production is exported (ADS Group 2019). The UK automotive ecosystem is considered within the most important in the UK good portfolio, as this sector trades is the one that exports the most (SMMT 2019). The nonagricultural products ecosystem embraces the infrastructure and supplier base developed for other manufactured products (others apart from the automotive, chemical, machinery, pharmaceutical and medicinal, and agricultural products ecosystems).
The next level in the ISM model, level 5, includes pharmaceutical and medicinal ecosystem, considered as one of the most successful manufacturing sectors in the UK (Kitson and Michie 2014), and the development of supporting organisations between private industries, academia and the government. The next level is the chemical ecosystem. The UK chemical ecosystem is regarded as one of the most successful in the world and a key player in the supply chain of industries, such as the aerospace and automotive industry (House of Commons 2019). The fourth level includes the following key enablers: strategic alliances and of manufacturing firms, investment in human capital development and supplier development programs. The fifth level only has privatisation of aerospace companies. Finally, the top level holds R&D public funding, the agricultural products and machinery ecosystems. According to the ISM methodology, this level contains the less influencer enablers as they do not trigger other factors.
The MICMAC methodology is also used in this research to categorise the thirteen key enablers. This methodology suggests that each enabler could be classified as autonomous, linkage, dependent or driver, depending on the level of influence to and from others. Results evidence that most of the factors fall under the linkage classification: supplier development programs, supporting organisations, investment in human capital development, geopolitical factors, R&D public funding, strategic alliances of manufacturing firms and chemical, machinery, pharmaceutical and medicinal, and nonagricultural products ecosystems. This category is characterised for having highly dependent and influent enablers as any action related to them drives an effect on them and others. The other categories embrace one key enabler each. Privatisation of aerospace companies is categorised as the most neutral factor, as is the only one with weak driving and dependence power. Agricultural products ecosystem is classified as the most dependable and less influencer factor. The automotive ecosystem is the enabler considered with the strongest driving power and weakest dependence power, as is the only one laying under driver classification.
The rationality of results on the categorisation of the key enablers, depicted in the ISM and MICMAC models, is validated using experts' judgement. Overall, results are expected to some extent, with some exceptions. For instance, one of the main findings is that the automotive ecosystem is categorised as the enabler with the strongest driving power and as part of the base for enabling all others. This finding is very much expected, as the UK automotive ecosystem is considered within the most important in the UK good portfolio, and its ecosystem, such as the supplier base, has helped the growth of the aerospace ecosystem. Another expected finding is that geopolitical factors, supporting organisations and pharmaceutical and medicinal ecosystem, are considered within the base for enabling all others, as illustrated in the ISM model (Fig. 3). Also, the categorisation of agricultural products ecosystem as the most dependable and among the fewer influencer factors is an expected result. This may be because its development depends on other factors, such as the geographical location of the country. In contrast, there are a couple of key enablers that their categorisation is not as expected. For instance, it is not expected that R&D public funding is within the least influencers, while nonagricultural products ecosystem is considered among the most influencers. Research and development public funding is expected to be among the most influencers, as the aerospace industry is highly dependent on technological developments triggered by R&D investments. One of the reasons behind this result may be because, nowadays, an important R&D investment comes from the private sector. In regards to the categorisation of most of the key enablers as linkage factors, this result is expected as it evidences a balanced ecosystem with interconnected components, which is a characteristic of a country with a developed economy.

The categorisation of key enablers for the evolution of the Mexican aerospace ecosystem
The categorisation of the key enablers for the evolution of the Mexican aerospace ecosystem is elaborated following nearly the same methodology as for the UK analysis. The only difference is the way in which experts' opinion is gathered. Here, individual meetings were held with each participant in which a description of the key factors was presented. The reason for taking the approach of individual meetings lies behind experts' availability. The group of participants consisted on four experts in the aerospace sector; all of them are Mexican nationals with more than ten years of experience in the aerospace sector and working in top-positions in recognised aerospace organisations (Table 12). A professional working as vice-president of a leading aerospace company and for the national association of aerospace industries. A researcher from the highest-ranked university in Mexico. An individual working as director of an aerospace research centre. A participant working for the government, focusing on developing policies to enhance the aerospace sector. As elaborated for the UK, experts' opinion is collected via SSIM (Table 13).

A MICMAC analysis for the Mexican aerospace ecosystem
In addition to the ISM methodology, the MICMAC approach is elaborated. Here, each factor is classified as autonomous, linkage, dependent or driver. Results, presented in Fig. 6, indicate a contrasting categorisation compared to the UK MICMAC model. Results indicate that, contrary to the UK, there is no factor under the linkage category. On the other hand, the automotive ecosystem (factor 6) is categorised in a similar way: it is considered as a driver for enabling all the others. Results are further discussed.

Interpretation of results of the categorisation of the key enablers that have fostered the Mexican aerospace ecosystem evolution
The analysis of the Mexican aerospace ecosystem resulted in an ISM model with four levels. The bottom level is considered as the base of the model, as it embraces the key enablers that foster all the others. Thus, according to the analysis elaborated in this research, geopolitical factors and the automotive ecosystem are considered as the key triggers for the evolution of the Mexican aerospace ecosystem. The next level in the ISM model, level 3, includes labour: low cost and highly-qualified. The following level holds foreign investment. Finally, the top-level embraces investment in human capital development, supporting organisations, agricultural products ecosystem and nonagricultural products ecosystem. Previous enablers are considered as the fewer influencer enablers as they do not trigger other factors.
The MICMAC methodology is also used in this research to categorise the eight key enablers of the Mexican aerospace ecosystem. Results evidence that most of the factors fall under the driver and dependent classification. Such results evidence an ecosystem characterised for having a lack of interconnected elements. In practical terms, it could reflect an imbalanced ecosystem typified by giving more strength to particular enablers, which is opposite to the findings from the developed aerospace ecosystem.
In addition, geopolitical factors, the automotive ecosystem and low cost and highly-qualified labour are considered as the enablers with the strongest driving power and weakest dependence power. It is relevant to highlight that, from previous enablers, the only one in common with the UK model is the automotive ecosystem. The previous finding reflects that the automotive ecosystem is considered as the most influential key enabler for the growth of both a developed and an emergent aerospace ecosystem.
On the other hand, investment in human capital development, supporting organisations and nonagricultural products ecosystem are the most dependent and fewer influencer factors for the growth of the Mexican aerospace ecosystem.
Finally, foreign investment and the agricultural products ecosystem are the most neutral factors for the development of the Mexican aerospace ecosystem, as they have been categorised with a weak driving and dependence power.
The rationality of results on the categorisation of the key enablers for the growth of the Mexican aerospace ecosystem, depicted in the ISM and MICMAC models, is validated using experts' judgement. Overall, results are expected to some extent. For instance, one of the main findings is that the categorisation of the enablers suggests that geopolitical factors, the automotive ecosystem and low cost and highly-qualified labour are among the base for enabling all others and with the strongest driving power. This result is very much expected as Mexico has been historically beneficiated from having as neighbour one of the most important economies in the world, meaning the USA. Certainly, the inherent conditions of Mexico as a developing economy, in conjunction with its geographical location, have fostered the growth not only of the aerospace ecosystem but of other industrial ecosystems, such as the automotive one. Consequently, it is also expected that foreign investment is influenced by previous enablers. Indeed, foreign companies have invested by opening manufacturing facilities in Mexico aiming at being closer (and with less operational costs) to their most important market, the USA. In regards to investment in human capital development and supporting organisations enablers, experts suggest that their categorisation among the fewer influencers is rational because, although they have fostered the aerospace ecosystem progression, they haven't helped with the required extent. In particular, expert's suggestions emphasise that strengthening of supporting organisations is imperative, as such organisations should be responsible for triggering the strategies that the Mexican aerospace ecosystem needs to grow. Experts claim that the existing supporting organisations promote mainly foreign investments rather than developing long-term strategies founded on R&D progression. On the other hand, the lack of enablers under the linkage category in the Mexican ecosystem may indicate an imbalanced ecosystem, based on the achievement of individual components rather than the interdependence of its components. Experts suggest that such results are coherent as Mexico, as a developing economy, is characterised for having a high level of inequalities.

KEY FINDINGS AND DISCUSSION
In this research, the key factors that have enabled the aerospace ecosystem evolution were analysed from two different perspectives: from a developed aerospace ecosystem, the UK, and an emergent one, Mexico. The key findings are summarised next: • A developed aerospace ecosystem, the UK, and an emergent aerospace ecosystem, Mexico, both consider similar key enablers for the evolution of their aerospace ecosystems. Most of the enablers found for the UK ecosystem were also found as enablers for the Mexican aerospace ecosystem. On the other hand, there are some differences. For instance, low cost and highly qualified labour and foreign investments are factors found in the emergent ecosystem that are not found in the advanced one. Both are inherent characteristics of a developing economy, so it is congruent that they are not considered as key enablers for a developed aerospace ecosystem with a developed economy. Moreover, pharmaceutical and medicinal ecosystem, strategic alliances of manufacturing firms, privatisation of aerospace companies, R&D public funding and the machinery ecosystem are part of the UK ecosystem that are not part of the Mexican ecosystem. Such results motivate to suggest that, although Mexico is going in the right direction, as evidenced by having similar key enablers as a developed ecosystem, Mexico perhaps is lacking critical enablers. In regards to the pharmaceutical and medicinal ecosystem in Mexico, this sector has been recently considered as an emerging one (Meraz-Rodríguez et al. 2019;Padilla and Suarez 2018). In regards to strategic alliances of manufacturing firms and privatisation of aerospace companies, evidence suggests that the Mexican aerospace ecosystem is at least two steps far from this achievement. This is because, as in 2019, both enablers are not applicable to the Mexican aerospace ecosystem as there is not any Mexican public aerospace company. Thus, the Mexican aerospace ecosystem possible needs to develop as a first step a public aerospace company. Successful examples that the Mexican ecosystem could follow are Embraer, the Brazilian aerospace manufacturer founded in 1969 as a public company but denationalised in 1994, and Bombardier, the Canadian public aerospace manufacturer, also founded in 1969 (Yamashita 2009).

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The automotive ecosystem and geopolitical factors have been considered by both ecosystems as the base for enabling the aerospace ecosystem evolution. In regards to the UK ecosystem, the geopolitical factors refer in particular to the trade agreements of the UK with other countries, such as the ATCA with the EU and other 20 countries, and the BASAs with the USA, Canada and Brazil. In regards to the Mexican ecosystem, Mexican geopolitical condition motivates foreign manufacturing firms to locate production facilities in Mexico and send duty-free products to the USA. Although the Mexican economy is considered as a developing one, it is positioned within the top-ten exporters in the world thanks mostly to its geographical position and free trade agreements with the USA. Mexico is part of the NAFTA and has BASA with the USA. The automotive ecosystem is considered among the most significant industrial sectors for both countries. Evidence suggests that it is considered the most important industrial sector in Mexico (Padilla and Suarez 2018), and it represents the UK largest sector of exported goods (SMMT 2019). Such results inspire to suggest that perhaps Mexico partially has already the infrastructure required to enable its aerospace ecosystem, as the automotive ecosystem infrastructure is considered as a driving force behind the exports of industrial goods in a developed ecosystem (SMMT 2019).

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The categorisation of some of the key enablers differs among developed and emergent aerospace ecosystems. For instance, contrary to the UK aerospace ecosystem, in the Mexican ecosystem, the supporting organisations key enabler is considered among the least influence factors. Evidence suggests that the UK ecosystem has created robust supporting organisations aiming at the development of the aerospace ecosystem. Such organisations have been essential for the elaboration and implementation of enhancement policies. Moreover, another key finding falls out from the validation with experts on the Mexican aerospace ecosystem. Expert's suggestions emphasise that strengthening of supporting organisations is imperative, as such organisations should be responsible for triggering the strategies that the Mexican aerospace ecosystem needs to grow. Expert's claim that most of the existing supporting organisations have the attraction of foreign investments as their main strategy, rather than developing long-term strategies founded on R&D progression.

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Developed aerospace ecosystems denote a more balanced ecosystem than emergent ones. The previous finding is evidenced in the MICMAC analysis: while most of the factors of the developed ecosystem fall under the linkage category, there is not any factor of the emergent ecosystem under this category. The fact that most of the elements of the developed ecosystem fall under the linkage classification denote an ecosystem characterised for having higher interconnected elements. Meaning that any action of these factors has an impact on the entire ecosystem. On the other hand, the lack of enablers under the linkage category in the Mexican ecosystem may indicate an imbalanced ecosystem, which is based on the achievement of individual components rather than the interdependence of its components.
The ISM and MICMAC analysis depict more balanced models for the UK than Mexico. Previous findings could lead to the conclusion that, if a developing aerospace ecosystem wants to improve its aerospace ecosystem, perhaps needs to develop and prioritise more factors as a developed one, like the UK.

LIMITATIONS OF THE STUDY
After a literature review, it is concluded that, although there is extensive information published on the aerospace sector, there is not a unique report containing all the key enablers for the evolution of the UK or the Mexican aerospace ecosystems. Consequently, in this research, this gap is filled to some extent. In this research, a total of 13 key enablers for the development of the UK aerospace ecosystem and 8 for the Mexican one is considered. This study proposes a list of key enablers intending to contain relevant key enablers suggested by recognised organisations and experts. It is assumed that the list of key enablers proposed in this research is not fully comprehensive, but is sufficient to some extent for the elaboration of enhancement proposals.

DATA AVAILABILITY STATEMENT
All data sets were generated or analyzed in the current study.