Flight information region (FIR) refers to a specific area within airspace wherein information regarding air traffic flow is provided depending on the type of airspace [1]. Since 1947, FIR zoning has been determined based on international agreements through the International Civil Aviation Organization (ICAO), which bases its judgements on aspects of flight safety. Thus far, global airspace has been divided into more than 290 FIRs. The airspaces of several small countries are merged into a single FIR; for instance, the FIR ROBERTS comprises the airspaces of Guinea, Liberia, and Sierra Leone. In the case of countries with vast airspaces, the airspace is divided into several FIRs, such as Indonesia, which has two FIRs: Jakarta and Makasar (Fig. 1) [2].

This study addresses the alignment of the Singapore FIR, focusing on the problems of the control of Indonesian airspace by foreign FIRs, particularly those above Batam, Riau Islands, and Natuna. Although Indonesia currently has demonstrated considerable capability in the field of technology, particularly information and communication technology, the speed and accuracy of the delivery of information technology and its alternatives, as well as a variety of practical solutions, need to be considered. In the past 1–2 decades, many developed countries and even developing countries have begun to devote considerable attention to the use of information and communication technologies (ICTs) and human resources in the fields of navigation, aviation safety technology, and others. Related to this, Indonesia is considered a sovereign nation. As such, any sovereign country is justified to take any action under the principles of international law and the United Nations Charter to maintain its sovereignty, including maintaining territorial integrity against all threats at any risk [3]. In addition, the Aviation Law allows the transfer of control of the FIR from Singapore, including the confrontation of possible obstacles that may be presented in realizing that will.

Fig. (1). FIR controlled by Indonesia Government. The AirNav office is shown as red, blue, and grey point. Also, the Singapore FIR is shown in red dash line (source: AirNav, 2018).

The initial transfer of the control of the FIR over the Natuna Islands airspace to Singapore was discussed at the ICAO meeting in March 1946, in Dublin, Ireland, where the distribution and management of the FIR were addressed. As traffic in Malacca was increasing rapidly, the ICAO stressed the creation of an air traffic system (ATS); however, at that time, Indonesia had just become an independent country, and no Indonesian delegation was present at the meeting. Ultimately, the FIR above the Natuna Islands airspace was established under the name FIR Singapore, with sectors A, B, and C (Fig. 2) given to Singapore, which was still a British colony.

In 1996, the FIR agreement between Indonesia and Singapore became a legal product (contractual treaty) binding the two countries. The main points listed in the Indonesia–Singapore FIR Agreement [4] are as follows:

(1) Limits in the agreement are set based on the United Nations Convention on the Law of the Sea 1982 treaty.

(2) Indonesian airspace above the Natuna Islands region is divided into sectors A, B, and C

(3) Indonesia delegates responsibility for providing flight navigation services within sector A to Singapore, from sea level to an altitude of 37,000 feet.

(4) Indonesia delegates responsibility for providing flight navigation services within sector B to Singapore, from sea level to an infinite altitude.

(5) Sector C is not included in the FIR agreement between Indonesia and Singapore. However, aviation traffic management in sector C must be coordinated between Indonesia, Singapore, and Malaysia.

On behalf of Indonesia, Singapore imposes a flight or route air navigation service charge in the Indonesian jurisdictional airspace, specifically sector A. As an area in the northern part of Singapore, whereas sector C covers the northern part of sector B, which is connected to the South China Sea. Over time, the FIR, which is controlled by Singapore, has become a strategic area and is busy with international flights. In 1973, joint management of the ABC sector by Singapore and Malaysia began, with Singapore controlling altitudes above 24,500 feet and Malaysia below 24,500 feet.

Indonesia once officially raised the issue in the Regional Air Navigation (RAN) Meeting held in May 1993 in Bangkok, which was attended by countries in the Asia and Pacific region. In the RAN meeting, the FIR alignment over Natuna was resolved bilaterally by Indonesia and Singapore; however, an agreement was not reached. This occurred not because Singapore intends to create complications for Indonesia. Nevertheless, the Natuna region has entered into an agreement with Malaysia that was agreed upon through the formulation of the Nusantara State Regime Law (Malaysian Rights in the Territorial Sea, Archipelago Waters, and Airspace Above the Waters and Territories of the Republic of Indonesia) signed in February 1982 and ratified through Law No. 1 of 1983 [5]. Therefore, Malaysia needs to be involved as well in discussions regarding the dispute of the FIR over Natuna. Consequently, the FIR issue above Natuna has become even more tangled with the increasing number of parties involved.

Referring to the FIR provisions determined under Article 28 of the Chicago Convention 1944 [6], which was further elaborated in Annex 11 concerning air traffic services [1], Indonesia is required to provide flight navigation facilities and services following the provisions of the Convention. However, in Annex 11 [1], Indonesia can delegate such supervision to another country (Singapore) if it deems itself unable to supervise air traffic over the sovereignty of the Republic of Indonesia, following Article 262 paragraph 1 letter a of the Aviation Law No. 1 of 2009 [7]. The FIR limit does not necessarily have to be aligned with the administrative or territorial boundary of a country. The definition of territory can be adjusted to the development of international provisions, following the provisions of the territorial states of the archipelago, while the airspace of sovereignty is located above the area. From the perspective of geopolitics, space is the core because it is a vehicle for political and military dynamics. De facto and de jure control of space is the legitimacy of political power. Increased or reduced state space can be caused by various aspects that are always associated with the honor and sovereignty of a state and nation [8].

Fig. (2). Singapore FIR over the Indonesia Airspace area (Source: http://masyarakathukumudara.or.id/wp-content/uploads/2016/02/FIR.png).

According to international law, Indonesia has sovereignty over the airspace above the land and sea area to a height where the air reaches outer space. Until now, there has been no international agreement regarding the high airspace in the sky. However, there is an agreement that airspace does not cover outer space. Some countries claim airspace to an altitude of 100 km into the air; however, some theories state that the height of airspace depends on where fixed-wing aircraft can fly using aerodynamics. The national air space of a country is used either to support national interests or accommodate international aspirations, including flight security and safety regulated by international law and ratified into the national law of the country of concern [9]. The sovereignty of the air space gives each state exclusive right to its own air territory and aircraft within that territory without permission are seen and treated as intruders [10]. International airspace arrangements were established based on the 1944 Chicago Convention [11]. The violation of Indonesia sovereignty is shown in the influence of the Singapore Civil Authority on defense and security in Indonesian airspace, where the Singapore Civil Authority sets the Danger Area in MTA 1 (Military Training Area) and MTA 2 and the Flight Information Region, which is above the Indonesian territory as a military training area that makes the area an area a prohibited zone unilaterally without agreement with Indonesia [12, 13].

Several publications have discussed the hot issue of Indonesia – Singapore FIR alignment [12-18]. Novika Maharani examined the legal basis of FIR control in Singapore in the context of Singapore’s FIR realignment in Indonesia and explained that Indonesia, as a sovereign island nation, had the right to manage its air space under Article 28 and Annex 11 [16, 17]. Thus, Singapore only had a legal basis in controlling the FIR from the 1946 RAN Meeting. The next step in the realignment effort was to form an inter-department working group consisting of the Ministry of Transportation, Ministry of Foreign Affairs, Indonesian Air Force Headquarters, Ministry of Defense, BNPP (Badan Nasional Pengelola Perbatasan - National Border Management Agency), and other agencies in an effort to prepare the FIR realignment, especially the establishment of a roadmap and working papers [17]. This roadmap details the steps to prepare for realignment. Furthermore, the working paper is a proposal for a realignment to be submitted to the ICAO in the Asia Pacific Air Navigation Planning and Implementation Regional Group (APANPIRG) session. However, Bakhtiar et al. described that limitation of the Indonesian government is the defense tools capacity owned by the Air Force, who has not reached the minimum limit of the defense forces [18]. This fact shows the weakness of the Indonesian government in the alignment process.

Indonesia has the means to be able to take back the delegation of the FIR [13]. In addition to delegating the FIR to Singapore, Indonesia also gave Malaysia rights to sea and air communication connecting West Malaysia and East Malaysia, through areas that are a part of Singapore's FIR. Indonesia has a sound legal basis for taking over the FIR area above Natuna Island. Zone A is under the supervision of Singapore in return for services; however, it can still be returned if Indonesia can demonstrate its territorial control. Malaysia has given indications of continuing to support Singapore's control of the FIR for Natuna Island, which, in principle, contains parts in which Malaysia, Singapore, and Indonesia maintain sovereignty. The management of the FIR, which is part of the sovereignty of the Indonesian airspace above the Riau and Natuna islands, by Singapore, has a legal basis.

Referring to Law No. 1 of 2009, flight navigation services are delegated to other countries based on the agreement that must be evaluated and served by the flight navigation service provider no later than 15 years after this law is put into force or before the year 2024 [7]. Indonesia is currently ready (Human Resource and Technology) to take over the FIR above the Riau Islands airspace. However, several issues still need to be resolved. One is the lack of support and trust from the ICAO toward Indonesia. Aviation safety must be the basis of the FIR alignment. Proving to the ICAO that Indonesia is reliable in terms of safety considerations is a priority. In addition to the safety of the paths of aircraft landing or taking off at Changi Airport, this should be considered when determining the new Singapore FIR. The socialization of the ability of Indonesian navigation services has not been optimal. Few countries possess detailed awareness regarding Indonesia's ability to provide in-flight navigation services; thus, the support toward Singapore is currently strong.

Based on the abovementioned description supported by data and facts, this study was conducted with two aims. Firstly, we analyze the readiness of the Indonesian government to convince the ICAO and the international community that Indonesia can control, manage, and secure the Natuna FIR airspace with respect to flight safety in the Natuna FIR region. Secondly, we formulate a grand design and roadmap of the Natuna FIR air control alignment stage as a form of enforcement of national airspace based on safety. Based on the past study review [12-18], the grand design and roadmap of the Natuna FIR air control alignment have rarely, if at all, discussed in Indonesia – Singapore Alignment topics.

In this study, two types of data were classified: quantitative and qualitative. Qualitative data were sourced from in-depth interviews with several key informants, namely the Commander of Tanjung Pinang Airbase, AirNav (Indonesia state-owned corporation that in charge of Aviation Navigation Services), and FIR practitioners. The quantitative data were sourced from primary and secondary data. Fundamental data in the form of interviews with pilots were obtained through previously prepared questions. This study randomly sampled pilots from the Indonesia pilot communities group mailing list. We asked pilots who have experienced communication with the ATC at Tanjung Pinang. Unfortunately, the online system questioner was not very desirable; then only 50 pilots were willing to participate. Secondary data are the data that have been processed or analyzed and stored in the form of writings, opinions, journals, books, and other literature for which the data have been tested and can be held accountable for its truth.

Miles and Huberman (1994) qualitative data analysis techniques consist of three stages: data reduction, data display, and conclusion drawing. Data reduction or data simplification is continuously performed during research, such that the data collected for research analysis and discussion can be clearly and concisely distinguished. Data display is the presence of data that have been previously filtered/simplified, in addition to analyses and explanations, to strengthen the arguments raised in the study. Conclusion drawing refers to summarizing the discussions and investigations conducted during research.

Data were collected from interviews and online media sources, in which verbatim and selected statements relevant to the topic and research needs were processed through the application of data reduction techniques. After the data were selected, the analysis was carried out by comparing the obtained data with the theories and concepts used in the study to reveal the correct direction for the FIR alignment. After analyzing and recognizing the level of readiness of the Indonesian government for FIR alignment based on the ideal concept of the theory used, conclusions were drawn.

To evaluate the validity and reliability of this study, the authors employed the Structural Equation Model (SEM) approach. SEM can also be used to analyze the model and determine the level of conformity of the model, commonly referred to as the suitability index [19]. Bollen stated that SEM can simultaneously analyze all variables to determine the correlation, variance, covariance, index of conformity, and level of confidence of the components of the model obtained [20]. This analysis was used to evaluate air traffic control (ATC) performance. Furthermore, a Geographic Information System (GIS) approach also implements to evaluate the spatial area of Indonesia – Singapore FIR. The GIS technique plays an important role in planning and managing the FIR [21, 22]. As in this study, a recommendation of Indonesia – Singapore FIR area represents in a spatial way using the buffer and dissolve technique.

Although the sovereignty of Singapore's FIR alignment is not an issue, the determination of the FIR is under the control of the ICAO. Aviation safety has become the only important concern in the harmonization of the Singapore FIR with that of Indonesia. Even Indonesia has proven the improvement of flight safety performance. Until now, the Indonesian government has not been able to carry out the alignment process because of diplomacy factors with ICAO and Singapore. The alignment–stage roadmap is composed of operational, tactical, and strategic stages that were provided in this study. Commitment from all stakeholders is needed to demonstrate to the ICAO that Indonesia is worthy of managing the Singapore FIR. Better coordination between agencies included in the Indonesia FIR alignment team is required. To facilitate the alignment process, tactical steps are needed to build a safe affiliate system that meets ICAO safety standards. Lastly, the recommended FIR area that is based on a 40-mile radius from the Standard Instruments Departure became an interesting finding in this study. Based on this approach, the safety factor of the Singapore side and the sovereignty of Indonesia will be accommodated.