New ICAO Obstacle Limitation Surfaces (OLS)

The International Civil Aviation Organization’s (ICAO) Amendment 18 marks the most significant overhaul of aerodrome safeguarding in decades. By moving away from static, one‑size‑fits‑all obstacle limitation surfaces toward a performance‑based model, the new framework reflects advances in aircraft capabilities, satellite navigation, and procedure design. Splitting the legacy OLS into Obstacle Free Surfaces (OFS) and Obstacle Evaluation Surfaces (OES) allows regulators to protect only the airspace truly needed for safe operations, while still providing a clear trigger for risk‑based aeronautical studies when obstacles intrude.

For the United Kingdom, the transition reshapes daily operational planning at every certified aerodrome. The integration of Aeroplane Design Group (ADG) categories—based on wingspan and take‑off speed—means that smaller regional airports may see a reduction in protected volumes, potentially freeing land for development, whereas larger hubs could face expanded safeguarding zones. Operators must overhaul digital airspace models, refresh obstacle databases, and adopt new ADG‑specific surface calculations well before the 2030 compliance date. Failure to align with the new OLS could result in delayed planning approvals, increased mitigation costs, or even restrictions on certain aircraft types.

Recognising the complexity of this shift, the UK Civil Aviation Authority (CAA) has scheduled a series of workshops throughout 2026, targeting aerodrome managers, planners, and developers. These sessions aim to demystify OFS and OES application, outline transition timelines, and share practical case studies that illustrate risk‑based mitigation strategies. By engaging early, stakeholders can embed the new methodology into their long‑term capital projects, avoid costly redesigns, and maintain regulatory compliance, positioning the UK aviation sector to benefit from a more efficient, safety‑focused safeguarding regime.