Aeronautical Information Management

Obstacle Evaluations

ATNS is responsible for conducting Annexure 14 Obstacle Assessments in line with Part 139 of the Civil Aviation Act 13, of 2009 (Civil Aviation Regulations 2011).


The construction of new buildings and infrastructure like masts and power lines, in and around the vicinity of airports could potentially effect flight safety, and therefore require assessments to be conducted to determine if these new buildings and infrastructure infringes on the obstacle limitation surfaces established around each airport

The purpose of the Annex 14 Obstacle Limitation Surfaces (OLS) is to define the volume of airspace that should be ideally kept free or safeguarded from obstacles, and to take the necessary measures to ensure the safety of aircraft, and thereby the passengers and crews aboard them, while taking-off or landing, or while flying in the vicinity of an airport.


The Aeronautical Information Department at ATNS oversees all Obstacle Assessments.

Designated Obstacle evaluators, in the Aeronautical Information section are responsible for all Obstacle Assessments.


ATNS accepts applications for Obstacle Assessments directly from clients. Applications may be forwarded electronically, via the ATNS website, by email or post.

Please note there’s a charge attached to this service.

The applicant must outline the details of the obstacle their desire to be evaluated. The following information is pertinent for the completion of any Obstacle Assessments:

    • The structural characteristics of the obstacle.
    • The coordinates for the location of the obstacle (presented in WGS84 format – Degrees, Minutes, Seconds to at least 4 decimal places).
    • The heights and elevations of the obstacle.
    • Site plans and relevant documents that may be deemed crucial.
    • Any other additional information that may assist in the assessment

Applicants will be informed on receipt of the application.

Applications may take up to 14 working days to process.

Any delay in the processing of the applications will be duly communicated to the applicant.