Seongnam City Submits Revised Altitude-Restriction Easing Plan to Defense Ministry...Height Limits Expected to Rise by Up to 135m

Revised and resubmitted with supplements to the three previously rejected options
Seeking a reasonable application of aviation safety standards

Seongnam-si in Gyeonggi Province (Mayor Shin Sangjin) announced on the 10th that it had prepared a revised plan supplementing the proposal to ease altitude restrictions in Flight Safety Zones 5 and 6, which the Ministry of National Defense had not accepted, and resubmitted it to the ministry.

Map of altitude-restricted flight safety zones in Seongnam-si. Provided by Seongnam-si.

The revised plan consists of three options to ease altitude restrictions over an area of approximately 45 square kilometers in Flight Safety Zones 5 and 6, covering 24 neighborhoods including Taepyeong, Sinheung, Sujin, Seongnam, Yatap, and Imae. In Seongnam-si, about 80 square kilometers out of a total area of 141.8 square kilometers are designated as altitude-restricted zones, and flight safety zones are classified from Zone 1 to Zone 6 based on the runway of Seoul Air Base.

To resolve the altitude restriction issue, Seongnam-si launched a research study in September 2023, collected residents' opinions, formulated five options for easing altitude restrictions, and officially requested their adoption from the Ministry of National Defense in June 2025.

Subsequently, the Ministry of National Defense accepted two of the options: (1) revising the Enforcement Decree of the Military Bases Act to use ground surface as the reference point (August 26, 2025) and (2) issuing a notice changing the flight safety zones in Seongnam-si (September 27, 2025). In contrast, the ministry indicated that it would be difficult to accept three other options: (1) changing the turning approach route of aircraft at Seoul Air Base from the east side of the runway to the west side (toward Cheonggyesan Mountain), (2) establishing special turning approach procedures, and (3) easing altitude restrictions by the margin corresponding to the conservatively set minimum obstacle clearance altitude.

Believing that the three unaccepted options are in fact crucial to achieving meaningful relaxation of altitude regulations, Seongnam-si reexamined the ministry's reasons for non-acceptance from an aeronautical perspective, incorporated residents' opinions, and prepared a supplemented revised plan, which it has now submitted again.

The main elements of the revised plan are: (1) easing altitude restrictions within the turning approach area, (2) easing altitude limits in areas where turning approach procedures are not operated, and (3) easing altitude limits through the establishment of special turning approach procedures. Depending on whether the Ministry of National Defense accepts the plan and on local conditions, the affected areas are expected to see altitude restrictions eased by at least 15.96 meters and up to 135.75 meters.

In addition, Seongnam-si requested an amendment to the standards so that, when calculating the shielding surface defined in Article 2, Subparagraph 6 of the "Directive on the Management of Military Bases, Military Facility Protection Zones, etc."—that is, the area that obscures the flight path—the height of trees is included rather than excluded as is currently the case.

Seongnam-si also cited cases within Seoul Air Base where construction was permitted even when military facilities exceeded the altitude-restriction surface, after undergoing a flight safety impact assessment (one case in 2020 and one case in 2021). At the same time, the city requested that altitude restrictions be applied flexibly to civilian buildings outside the shielding zone if assessment results confirm that they have no impact on aviation safety.

Mayor Shin Sangjin of Seongnam-si said, "The altitude restriction issue is a task that must be resolved, even if it requires multiple rounds of supplementation and consultation," adding, "We will persistently consult with the Ministry of National Defense so that the protection of citizens' property rights and aviation safety can be harmonized."

This content was produced with the assistance of AI translation services.