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UK Civil Aviation Regulations

These are published by the CAA on our UK Regulations pages. EU Regulations and EASA Access Guides published by EASA no longer apply in the UK. Our website and publications are being reviewed to update all references. Any references to EU law and EASA Access guides should be disregarded and where applicable the equivalent UK versions referred to instead.

Please also refer to our webpage giving an overview of the requirements and notification processes for obstacles in UK airspace.

Obstacles 100m or higher above the surface

In accordance with UK legislation and the standards and recommended practices contained in the Annexes to the International Convention on Civil Aviation, there is a Civil Aviation Authority (CAA) requirement for all known structures (land based and off-shore) with a height of 100 metres (m) / 328 feet (ft) or more above the surface in UK airspace to be published within the UK Aeronautical Information Publication (AIP) (available on the NATS Aeronautical Information Service (AIS) website).

Details of those obstacles of which the CAA has been notified are published in an Electronic Data File, which is located in the ENR 5.4 section of the UK AIP and updated every 28 days. To view the current Electronic Data File, select the ENR 5.4 ICAO Area 1 Obstacle Dataset link from the list of digital datasets available on the NATS AIS website. Such obstacles are also charted on the Visual Flight Rules (VFR) charts produced by NATS on behalf of the CAA. This notification / charting is drawn from the UK’s master database, known as the Digital Vertical Obstruction File (DVOF), which is managed by the Defence Geographic Centre (DGC).

For landmark purposes, a small number of obstacles below 100m are shown on the VFR charts. Temporary obstacles (or changes) of less than 90 days duration will be notified by NOTAM only and will not appear in the Electronic Data File or on the VFR charts.

Operators/developers should ensure that details of all existing or proposed structures with a height of 100m / 328ft or more above the surface are notified to the CAA in accordance with the guidance on our Obstacles overview and Obstacle notification webpages.

Obstacles less than 100m above the surface

Aerodrome obstacles

As explained on our overview webpage, an obstacle that is located on an area intended for the surface movement of aircraft or that extends above a defined surface intended to protect aircraft in flight is categorised as an aerodrome obstacle. It should be noted that:

  • this applies regardless of the obstacle’s height.
  • obstacle limitation surfaces can extend to distances greater than 15 kilometres from the runway thresholds.
  • operators/developers must ensure that positive responses are received from all affected aerodromes before erecting an obstacle in a safeguarding area.

Low-level airspace users

To ensure the safety of airspace users operating below 100m / 328 ft above the surface (such as military, police, air ambulance, coastguard/search and rescue low flying activity), the Military Airspace Management Cell – Low Flying (MAMC LF) and DGC have an interest in lower structures. Operators/developers are strongly advised to engage with MAMC LF and DGC to determine if details of a structure below 100m / 328 ft above the surface should be submitted for NOTAM action and subsequent inclusion in DVOF.

Contact us

If you have any questions, please contact Airspace Regulation between the hours of 08:30 and 16:30 Monday to Friday (excluding Public Holidays).  It may not be possible to action messages/notifications submitted after 16:00 until the next working day.

Planned periods of extended closure of the Airspace Regulation section will be notified here:


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