Obstacle Control Surfaces - The main requirements at an Aerodrome



Obstacle Control Surfaces of an Aerodrome

 

  

 

 

 

3.4 Obstacle Control

 

Every aerodrome operator should establish Obstacle Limitation Surfaces (OLS) in accordance with

ICAO SARPs for safe take-off and landing of aircraft. Objects other than approved visual and navigational aids should not be located within the obstacle restriction area or the aerodrome without specific approval of each state’s CAA. If there are any objects penetrating these surfaces, the aerodrome operator should remove or mark and/or light them.

 

3.4.1 Establishment of OLS (Obstacle Limitation Surface)

 

 

Establishment of obstacle limitation surfaces at each aerodrome depends on types of instrument

runways, either non-precision approach or precision approach runways. Established obstacle control

surfaces must be prevented from becoming unusable by the growth of obstacles. Obstacles range

from fixed - (temporary or permanent), to mobile objects, or parts thereof which penetrate the obstacle limitation surfaces.

 

The following OLS should be established for anon-instrument runway and non-precision instrument

runway:

 

Conical Surface;

 

• Inner Horizontal Surface;

 

• Approach Surface;

 

• Transitional Surface; and

 

• Take-off Climb Surface.

 

 

The following OLS should be established for a precision instrument runway:

 

• Outer Horizontal Surface (as may be defined by the state);

 

 

• Conical Surface;

 

• Inner Horizontal Surface;

 

• Approach Surface;

 

• Inner Approach Surface;

 

• Transitional Surface;

 

• Inner Transitional Surface;

 

• Balked Landing Surface; and

 

• Take-off Climb Surface.

 

 

Where two OLS surfaces overlap, the lower surface must be used as the controlling OLS. Detailed information about ‘Dimensions and slopes of obstacle limitation surfaces’ can be found in ICAO Annex 14,

 Height of the obstacle in relation to the aerodrome elevation and   

The period for which it will remain an obstacle (if it is temporary obstacle)

 

Temporary obstacles and transient (mobile) obstacles, such as road vehicles, rail carriages or ships, in close proximity to the aerodrome and which penetrate the OLS for a short duration should be referred to the CAA to determine whether they will be a hazard to aircraft operation. Fences and levee banks that penetrate the OLS should be treated as obstacles. Obstacle surveys of areas underlying the obstacle control surfaces at both proposed and existing airports are performed to identify the location and height of objects that may constitute infringements of these surfaces. Survey specifications are used to obtain the obstacle data necessary to comply with the ICAO SARPs contained in the relevant Annexes and the requirements of each State’s regulations. Obstacles must be designated: for example, tree, hill, pole, tower, spire, vent, chimney, mast, post, antenna, building, house, etc.

 

3.4.2 Procedures for Aerodrome Operators to Control OLS

Aerodrome operators must establish procedures to monitor the OLS and the critical obstacles associated with aircraft operation and have them included in the aerodrome manual. Each aerodrome operator should monitor the OLS applicable to the aerodrome and report to its civil aviation authority any infringement or potential infringement of the OLS. When a new obstacle is detected, the aerodrome operator should disseminate the information to pilots through a NOTAM, in accordance with aerodrome reporting procedures set out in Chapter 3.2. Information on any new obstacle should include:

• The nature of the obstacle – for instance, structure or machinery;

 

• Distance and bearing of the obstacle from the start of the take-off of the runway, if the obstacle is within the take-off area, or the approach area; 

 

3.4.3 Type A Charts

A Type A chart is a chart which identifies information on all significant obstacles within the take-off area of an aerodrome up to 10km from the end of the runway. A Type A chart should be prepared for each runway that is used in international operations. Obstacle data to be collected and the manner of presentation of the Type A chart should be in accordance with the standards and procedures set out in ICAO Annex 4. An electronic chart may replace a paper chart. Where a Type A chart has been prepared and issued the take-off flight area should be monitored and any changes to the Type A chart information must immediately be communicated to all users of the Type A chart. Obstacles may be recorded in an electronic Terrain and Obstacle database (e-TOD).

 

 

 Source - ACI