OLS Surfaces - Pager Power
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OLS Surfaces

OLS Surfaces
March 10, 2019 Mike Watson

Obstacle Limitation Surfaces (OLS) are used for protecting aircraft from obstacles around airports and military bases. The surfaces are:

  1. Take Off Climb Surface (TOCS)
  2. Approach Surface
  3. Inner Horizontal Surface
  4. Transitional Surface
  5. Conical Surface
  6. Outer Horizontal Surface

Further details regarding the individual surfaces can be found here


OLS surfaces extend to a distance of 15 kilometres beyond the airport. The figure below shows that OLS surface altitude is determined by the ground elevation of the airfield rather than the ground elevation at the development location.


obstacle limitation surfaces

Figure 1 OLS Surface Principles

ICAO Annex 14

Dimensions of surfaces are specified by the International Civil Aviation Organisation (ICAO) in Annex 14 to the International Convention on Civil Aviation. Individual countries tend to specify their own surfaces for civil and military airfields – however these specifications are invariably based on the ICAO Annex 14 rules.

Surface Breaches

There are situations where obstacles higher than the surfaces are permitted and have been built. In some cases surfaces may be viewed as a trigger for consultation and further assessment. Where a new development is set to breach a surface a separate Safety Assessment may be required.

How Can Pager Power help?

We can:

  • Assess whether a development will breach obstacle limitation surfaces
  • Advise on maximum height of a development so that surfaces are not breached
  • Undertake Aviation Safety Assessments so that surfaces can be breached
  • Liaise with airport operators to assist in gaining planning permission
  • Advise on obstacle lighting
  • Advise on managing demolition orders

For more information contact Mike Watson on +44 1787 319001.


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