Singapore Implements Revised Obstacle Limitation Surfaces Standards and Recommended Practices
5 August 2025
Revisions will allow building heights around airports to be raised in Singapore while ensuring aviation safety
On 5 August 2025 (Singapore time), the Civil Aviation Authority of Singapore (CAAS) revised Singapore’s civil aviation regulations to bring into effect the revised set of Standards and Recommended Practices (SARPs) for Obstacle Limitation Surfaces (OLS) in Annex 14 to the Convention on International Civil Aviation.
2 The revised regulations will enable aircraft operations in Singapore to be safeguarded with more precision according to the specific type of operations at each airport and free up more airspace surrounding airports in Singapore for development. Specifically, this will present opportunities for building height limits and development intensity to be raised in some parts of Singapore.
3 Buildings in some parts of Singapore could potentially be raised by up to 15 storeys higher for residential developments or up to 9 storeys higher for industrial and commercial buildings. The actual allowable building height and development intensity is being studied by relevant agencies, taking into consideration supporting infrastructure capacity as well as the need to maintain a quality urban living environment.
Revised OLS SARPS in Annex 14
4 OLS, which are determined based on Annex 14 to the Convention on International Civil Aviation, define the surfaces or volume of airspace around aerodromes that must be kept free from obstacles to ensure safe aircraft operations and cannot be released for other uses.
5 In 2013, the International Civil Aviation Organization (ICAO) called for a significant review of the ICAO OLS SARPs. In 2015, an OLS Task Force (OLSTF) was established to undertake this review. The objective of ICAO’s review was to ensure the OLS requirements, which were first established in the 1950s, are effective in protecting airspace around an airport against obstacles such as buildings that could potentially affect aviation safety. Singapore was the chair of the OLSTF since 2017.
6 The revised OLS SARPs developed by the OLSTF were accepted by the ICAO Council on 28 March 2025 and became effective internationally on 4 August 2025 (Montreal time). The OLSTF used a data-driven approach, and took into account technological developments in aircraft avionics and air navigation systems. It also sought and incorporated input from States, industry and other ICAO technical panels in its review.
Revised Civil Aviation Regulations in Singapore
7 CAAS has revised its civil aviation regulations under Aviation Specifications 5 – Aerodromes, in an over 200-page document, to bring into effect the revised OLS SARPs. One key revision is the introduction of a new classification of surfaces into either Obstacle Free Surfaces (OFS) or Obstacle Evaluation Surfaces (OES), which collectively ensure that all objects that could affect aviation safety are accounted for. The OFS are surfaces closer to the runway which are critical for aircraft in the final phase of approach to land. The OES, on the other hand, are surfaces intended to protect the specific flight procedures and operations conducted at the runway. This classification allows for the appropriate OLS to be adopted for each aerodrome based on its specific operations instead of the previous one-size-fits-all model that may require more airspace to be safeguarded for aircraft operation, thereby freeing up more airspace for non-aviation purposes. See Annex A for an illustration of airspace freed up arising from the revised surfaces.
8 Mr Han Kok Juan, Director-General, CAAS said, “Singapore is honoured to contribute to this major review including through our chairmanship of the international taskforce. It will support developments and benefit many countries around the world, including for land-scarce Singapore. This effort underscores the value of collaboration through multilateral institutions and the ability of Singapore and Singaporeans to make meaningful contributions.”
9 For more information on the implementation of the revised OLS SARPs, please contact CAAS_ATS_ANSP@caas.gov.sg.
Annex A – Illustration of Airspace Freed Up Arising from the Revised Surfaces
About the Civil Aviation Authority of Singapore
The mission of the Civil Aviation Authority of Singapore (CAAS) is to grow a safe, vibrant air hub and civil aviation system, making a key contribution to Singapore's success. CAAS' roles are to oversee and promote safety in the aviation industry, develop the air hub and aviation industry, provide air navigation services, provide aviation training for human resource development, and contribute to the development of international civil aviation. For more information, visit www.caas.gov.sg.
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