STUDY ON THE DESIGN OF THE VFR (VISUAL FLIGHT RULES) CORRIDOR CONNECTING AIRPORTS IN NORTH SUMATRA PROVINCE

This research aims to design a VFR Corridor that can connect airports located in the province of North Sumatra, especially those airports that do not yet have a VFR Corridor. The research method used is Research and Development (R&D). Data was collected using observation, literature study, interviews, and documentation. The results showed that the current condition of the VFR Corridor has not connected the eight airports in the North Sumatra region. However, the eight airports can be connected with the new VFR Corridor design consisting of three segments. This design allows VFR aircraft to follow the VFR Corridor path rather than flying direct. In addition, the VFR Corridor design also ensures that the movement of VFR aircraft will not interfere with IFR aircraft following STAR at Kualanamu Airport in Medan and Sisingamangaraja Airport. This study has implications for improving the safety and efficiency of flight operations in the North Sumatra region. With a structured and connected VFR Corridor, VFR aircraft pilots have clearer guidance in air navigation, so the risk of collisions with IFR aircraft can be minimized. In addition, this design also supports the development of aviation infrastructure in North Sumatra, especially in facilitating connectivity between airports that do not yet have a VFR Corridor.


INTRODUCTION
AirNav Indonesia manages and serves flight navigation in Indonesia's 7,539,693 km2 of airspace following the signing of a bilateral boundary realignment agreement between FIR Jakarta and FIR Singapore on January 25, 2022.It was agreed that flight navigation services in the Riau Islands and Natuna that the Singapore FIR previously carried out would be transferred to the Jakarta FIR.The agreement was then ratified by Presidential Regulation No. 109 of 2022 on the Ratification of the Agreement between the Government of the Republic of Indonesia and the Government of the Republic of Singapore on the Boundary Adjustment between the Jakarta Flight Information Region and the Singapore Flight Information Region (Mithalina & Risnain, 2023).The Indonesian FIR is divided into two, namely: 1.The Jakarta FIR, which covers the western airspace of Indonesia, is managed by the Jakarta Air Traffic Services Center (JATSC) and its subordinate units and 2. The Ujung Pandang FIR, covering the eastern part of Indonesia, is managed by the Makassar Air Traffic Services Center (MATSC) and its subordinate units.
Indonesia's airspace is directly adjacent to several other countries airspace, including Australia (Melbourbe FIR & Brisbane FIR), Sri Lanka (Colombo FIR), Singapore (Singapore FIR), Malaysia (Kuala et al.FIR), Philippines (Manila FIR), United States (Oakland Oceanic FIR), Papua New Guinea (Port Moresby FIR) and India (Chennai FIR) (Azari, 2024).During 2022, every day, AirNav Indonesia served an average of 4,210 aircraft movements, both take-off or landing and overflying flights between countries in Indonesian airspace.The number of flight routes managed by AirNav Indonesia is 181, consisting of 117 domestic and 64 international routes.
Based on the scope of operations, flight navigation services are divided into Aerodrome Control Tower (TWR), Approach Control Unit (APP), Area Control Center (ACC), Aerodrome Flight Information Service (AFIS), and Flight Information Center (FIC).Meanwhile, based on the procedure, the types of services can be divided into Aerodrome Control Tower (TWR), Approach and Area Control Procedural (APP et al.), Approach Control Surveillance (APS), Area Control Surveillance (ACS), and a combination of TWR and APP procedural (combined).A simple profile of the services provided, the location, and the typical airspace served by AirNav Indonesia is illustrated in the following figure (A. Indonesia, 2022); (ERGA, 2023).3. Airnav Kualanamu Medan is an International Airport.International Airports are airports that are designated as airports serving domestic flight routes and flight routes to and from abroad (R. Indonesia, 2009).Since 2022?Kualanamu International Airport is also a Hub Airport.Hub Airports have a wide service coverage of airports that serve large numbers of passengers and cargo and affect economic development nationally or in various provinces (R. Indonesia, 2009).
The type of flight is based on the way of flight, namely instrument flight or instrument flight rules and visual flight or visual flight rules (RI, 2014).Visual Flight Rules (VFR) flight is a method of flight in which the pilot relies on visual sight for navigation rather than relying on flight instruments (Bupu, 2021); (Li et al., 2023).VFR Corridor is a flight path designed to support VFR operations, enabling more efficient and safer flights (Retno & Muchaddats, 2024); (Ahmadi et al., 2022).North Sumatra, as one of the main provinces in Indonesia, has several airports that play an important role in regional connectivity.
Current conditions in the North Sumatra region based on AIRAC AMDT 86 have 5 Segments.Not all airspace areas in North Sumatra have VFR Corridors, such as the Airport area in Sibolga and the Airport Area in Padang Sidemuan.This study aims to design a VFR Corridor connecting the main airports in North Sumatra, which will pass through several cities as a visual reference and is also equipped with latitude and longitude coordinates.The focus is on mapping the optimal path and potential for aviation development in the region.
Several airports in North Sumatra Province still lack VFR corridors, so the authors are interested in making the title Research Study Design of VFR Corridor Connecting Airports in North Sumatra Province.Based on the background description above, this study aims to design a VFR Corridor that can connect airports located in the province of North Sumatra, especially those airports that do not yet have a VFR Corridor.The benefits of this research are expected to provide a significant contribution to the aviation sector in North Sumatra Province.Firstly, by designing a VFR Corridor, this study will help enhance the safety and efficiency of flight operations, especially for general aviation and small aircraft that rely on visual navigation.Secondly, the implementation of a well-designed VFR Corridor can improve connectivity between airports, which in turn supports regional economic development by facilitating smoother and more reliable transportation of goods and passengers.Lastly, this research could serve as a reference for future studies and the development of aviation infrastructure in other regions of Indonesia, contributing to a more comprehensive and integrated national airspace system.

METHOD
The research method used is Research and Development (R&D).Data is collected through observation, literature study, and interviews with air traffic controller personnel Perum LPPNPI Medan Branch and experts in the field of procedure design and documentation.Data sources include laws, regulations, and ICAO documents such as Document 8168-Procedures for Air Navigation Services, Annexes, and relevant journals.

RESULTS AND DISCUSSION Description of Research Object
This research focuses on the airspace area without a VFR Corridor design.Table 4 shows the latitude and longitude coordinates at 8 (eight) airports in North Sumatra Province.Generally, the flight process is departing, climbing, cruising, descending and landing.Of course, this process is from one airport to another.To connect from one airport to another requires an airway or route.This route is divided into 2 (two): the route to fly instrumentally and visually (Arfiansah et al., 2021).Flying instrumentally and visually has a difference.Instrumentally means relying on the aircraft's instruments, while visually means that the pilot relies on landmarks or visual reference points on the ground.Current conditions in the North Sumatra region based on AIRAC AMDT 86 have 5 Segments, namely in the following table 5: Source: AIRAC AMDT 86 In North Sumatra, as in the table Table .5 Geographical Location of Airports above, there are 8 (eight) airports, which means there are still 3 (three) airports that have not been connected.From the data obtained from July -December 2021 to 2023, which can be seen in Table 4.3, aircraft heading to airports that have not been connected to the VFR Corridor, pilots fly directly; this condition disrupts IFR arrival aircraft whose approach follows the predetermined standard arrival (follow profile) to Kualanamu Airport and Raja Sisingamangaraja XII Airport.
Due to VFR aircraft flying directly, IFR aircraft cannot follow the arrival standard and must cancel STAR.Therefore, to anticipate this, it is necessary to design a VFR Corridor to avoid VFR aircraft flying directly or indirectly.Source: KNO Airnav Data   Point D Mursala Waterfall N014130600 E09827065 5.
Point O Aek Godang Airport N012356000 E09925500 Source: Processed Data

Coordinate Conversion to UTM (Universal Transfers Mercator)
Conversion is an activity to change coordinates from latitude/longitude to UTM using the transport tool (Chevy, 2015).This conversion is carried out with the aim of reading the coordinates specified during the drawing using Autocad.As in Figure 8.

Figure 8. Conversion Process Plotting Process
The plotting process uses an application on the Autocad web.In this process, each visual reference point or landmark coordinate obtained is entered so that the VFR Route image will appear, as shown in Figure 9.After the VFR Route is drawn, continue to draw the protection area to the right and left of the VFR Route of 5 NM each.The results of this process will produce a VFR Corridor image (Rachman et al., 2021).After all the design processes, the next step is to name each point.In giving names following the five letter name code (5LNC) rules in the ICAO 8168 document, for example, KODAP.KODAP is a significant point not characterized by the location of radio navigation facilities and is therefore given a pronounceable five-letter name code.(ICAO, 2018)The naming also considers the location or place of the point coordinates of the nearest city/district; the point is to make it easier for pilots to recognize the route.Point naming can be seen in Table 10 below.

CONCLUSION
This research concludes that the existing VFR Corridor in North Sumatra Province does not currently connect the eight airports in the region.However, through this study, a new VFR Corridor design has been proposed, consisting of three segments that effectively link these airports.The new design provides a structured pathway for VFR aircraft, ensuring they can navigate the corridor rather than flying directly between airports.Additionally, the proposed VFR Corridor design is carefully planned to ensure that the movements of VFR aircraft will not interfere with IFR operations, particularly those following the Standard Terminal Arrival Routes (STAR) at Kualanamu Airport in Medan and Sisingamangaraja Airport.This design aligns with the research objectives of enhancing connectivity and ensuring safe and efficient air traffic management in the region..

Figure 1 .
Figure 1.Service Unit Profile Source: Airnav Indonesia Annual Report 2022

Figure 3 .
Figure 3. Domestic flight traffic graph Based on data, Domestic flight traffic in 2023 has not exceeded the existing traffic limit in 2019, but traffic from 2020 to 2023 has increased slowly.In 2020-2021, the impact of COVID-19 is still very much felt, so flights are not maximized.

Figure 4 .
Figure 4. Domestic flight traffic graph International flight traffic in 2023 did not exceed the existing traffic limit in 2019, but traffic from 2020 to 2023 increased slowly, just like domestic flight traffic.Based on data from the Indonesian Ministry of Transportation Directorate General of Civil Aviation, North Sumatra Province has several airports, which we can see in Table3.

Figure 6 .
Figure 6.VFR Corridor Current Conditions in North Sumatra

Figure 7 .
Figure 7. Determination of Coordinates with Google Earth

Figure 9 .
Figure 9. VFR Route Drawing Process Drawing Track and DistanceCalculating track/direction and distance/distance from each coordinate using Compsyss tools.An example image in the picture below

Figure 11 .
Figure 11.VFR Corridor Design of North Sumatra Airport

Table 1 . Domestic Flight Traffic of Kualanamu International Airport
Table 1 shows flight traffic at Perum LPPNPI Kualanamu Branch from 2019 to 2023.
Source: Central Bureau of Statistics

Table 10 . Five Letter Name Code Point Naming
naming of Five LNC is outlined in Table 11, Table 12, and Figure 4.6 of the design results.

Table 13 . Segment C Track and Distance Table Sisinggamaraja Airport to AH Nasution Airport
Source: Processed Data