OBSTACLE LIMITATION SURFACES AND ASSESSMENT CRITERIA FOR PERMISSIBLE HEIGHTS FOR THE STRUCTURE AROUND THE AERODROMES

AIRPORTS AUTHORITY OF INDIA

OBJECTIVE

To control construction of buildings in area that may affect the safety or efficiency in aircraft operation as per guidelines of International Civil Aviation Organization The objective is to ensure obstacle free airspace around aerodrome to permit safe aircraft operations and to prevent aerodromes from becoming unusable by the unrestricted growth of obstaclesA series of obstacle limitation surfaces are defined which help in assessing the limits to which objects may project into the airspace

OBSTACLE LIMITATION SURFACES ( OLS )

Surfaces in the airspace above and adjacent to the aerodrome.

Extend beyond the boundary of the airport and therefore require protection by the enactment of Zoning Regulations for aircraft operation.

Provided by Instruments which regulates the erection of structures .

Applies to all the lands, including public road / structures adjacent to or in the vicinity of an airport.

Requirement of OLS

These obstacle limitation surfaces are necessary to enable aircraft to maintain a satisfactory level of safety while maneuvering at low altitude in the vicinity of the aerodrome specially in case of an emergency landing.

Consequence of not protecting the obstacle limitation surfaces.Limiting the distance for take-off and landings.

Raising the aerodrome Met. minima.

Reduction in the payload of aircraft

Methods of controlEnactment of height zoning protection by the local government authority

Establishing an effective obstacle removal procedures.

OTHER SALIENT POINTSGOVERNING DOCUMENT- SO 84E of January,2010

TAKE-OFF CLIMB SURFACE CONSIDERED FOR TAKE-OFF RWYs.OFZ i.e INNER APPROACH,INNER TRANSITIONAL APPROACH & BALKED LANDING FOR CAT II & ABOVE.PROVISION OF SHIELDING BENEFIT

NO OBJECT IS PERMITTED IN THE BASIC STRIP/OFZ EXCEPT THOSE WHICH ARE ESSENTIAL FOR NAVIGATION OF THE AIRCRAFT AND SUCH OBJECTS MUST BE FRANGIBLE.

AT ALL THE AIRPORTS THE APRONS, TERMINAL BUILDINGS, CONTROL TOWER, FLOOD LIGHT MASTS, NAV-AID INSTALLATIONS FALL IN TRANSITIONAL SURFACE.

GOI ORDERS (1)No building or structure shall be constructed or erected, or no tree shall be planted on any land within the limits specified as below in respect of Civil and Military Aerodromes as listed( annexure 1), aerodromes to be constructed or developed and notified by the Competent authority in future where there is any building, structure or tree on such land, the owner or the person having control of such building, structure or tree shall demolish such building or structure

Annexure 1.The land enclosed in approach funnels of the runway with a maximum distance of 300 meters , measured from each runway end along extended centre line of the runway,60 meters on either side of it.The land comprising within the runway strip of uniform width of 150 meters on either side of the centre line which extend to 60 meters beyond each extremity of the runway end along extended center line of the runway.

GOI ORDERS (2)

No building or structure higher than the height specified in annexure 2 shall be constructed or erected or no tree which is likely to grow higher than the height specified in annexure 2 shall be planted on any land within a radius of twenty kilometers from the aerodrome reference point ( ARP) of the aerodromes listed in Annexure 3).

AGA SURFACESTransitional surface

Departure / Approach surface

Inner horizontal surface

Conical surface

Outer Horizontal surface

DIMENSIONS OF BASIC STRIP

RUNWAYINSTRUMENT RUNWAYNON-INSTRUMENT RUNWAYCode LengthNo. (Metre)Width extending laterally on either side of the rwy C/L(Metre)Length beyond Runway end/stopwayWidth extending laterally on either side of the rwy C/L(Metre)Length beyond Runway end/stopway(Metre)1

Runway and Basic StripRUNWAYBasic StripBasic Strip150M60M150M60M

OBSTACLE CONTROL IN APPROACH SURFACEObjects which penetrate the approach surface are critical since they represent an erosion of the clearance between the final approach path, usually 3 degrees, and fixed or mobile obstacles on the ground.On an approach where the approach surface is significantly obstructed, the safe operation of aircraft requires raising the aerodrome approach meteorological minima thereby reducing the usability of the airport.If the object penetrates into the approach surface, the threshold is displaced, thereby reducing the available landing distance considerably putting restrictions in aircraft operation. This can have an adverse effect on the regularity of aircraft operations and could impose payload penalties on landing / take off of the aircraft.

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APPROACH SURFACEThe approach area shall be established from the smaller ends of the runway strip for each runway direction intended to be used for the landing of the aeroplanes. In relation to an instrument runway , means the area in the shape of an isosceles trapezium having the longer parallel side 4800 meters long and smaller side 300 meters long where the smaller and longer parallel sides are placed at a distance of 50 meters and 15060 meters respectively from the end of the runway end at right angles to the extended center line. Has a divergence of 15% on either sideHas a slope of 2% upto 3000M and 2.5% for next 3600M- having a flat section thereafter.

DIMENSIONS AND SLOPES OF APPROACH SURFACES (INSTRUMENT RWY)

RUNWAY Vertical Section(DIVERGENCE 15% ON EITHER SIDE Horizontal sectionCode No. LengthFirst Section Length SlopeSecond Section Length SlopeLength 1

Transitional surface

Means a specified surface sloping upwards and outwards from the side of the strip, and the approach surface to the inner horizontal surface or to a specified height.

Infringement of them by an obstacle results in the reduction in the clearance available whilst carrying out an approach to land or during a missed approach procedure.

Transitional Surface2250M315M315MApproach SurfaceTransitional SurfaceTransitional Surface1:7MAX PE 45MApp/Transitional SurfaceApp/Transitional Surface

ZONING MAP

App/Transitional SurfaceApproach/Transitional Surface Calculation

2250MApproach SurfaceMAX PE 45M1:501:7

Inner horizontal surfaceSpecified portion of a horizontal plane located above an aerodrome and its immediate environment. This surface establishes the height above which it may be necessary to restrict the creation of new obstacles, or remove existing obstacles, to ensure the safety of aircraft maneuvering by visual reference in the aerodrome circuit prior to landing. The inner horizontal surface is more significant for VFR operations. It also provides protection for circuiting aircraft following an instrument approach. It does not usually represent a critically limiting surface around a large aerodrome handling IFR traffic.

DIMENSIONS AND PERMISSIBLE HEIGHTS OF INNER HORIZONTAL SURFACE

RUNWAYINSTRUMENT RUNWAYNON-INSTRUMENT RUNWAYCode No. LengthRADIUS(METRE)HEIGHT(METRE)RADIUS(METRE)HEIGHT(METRE)1

Inner Horizontal SurfaceInner Horizontal Surface4000M4000MFlat at 45M Inner Horizontal Surface

Conical surface

Means a specified surface sloping upwards and outwards from the periphery of the inner horizontal surface.

It establishes the vertical limits above which it may be necessary to restrict the creation of new obstacles, or remove existing obstacles, to ensure the safety of aircraft maneuvering by visual reference in the aerodrome circuit prior to landing.

DIMENSIONS AND PERMISSIBLE HEIGHTS OF CONICAL SURFACE

RUNWAYINSTRUMENT RUNWAYNON-INSTRUMENT RUNWAYCode No. LengthHorizontal distance of Conical Surface beyond I.H.S (Met)Maximum height above I.H.S (Metres)Horizontal distance of Conical Surface beyond I.H.S (Met)Maximum height above I.H.S (Metres)1

OUTER HORIZONTAL SURFACE OHS shall extend from the edge of Conical Surface to 15000m from the ARP

Height of OHS - 300 M Above Aerodrome elevation

Slope 5% slope of Conical surface continues.

Slope from Approach Surface edge is 1:7 from 150M to 300M( Extends upto 1050M from Approach edge)

DATUM FOR AGA CLEARANCEAPPROACH SURFACES: - elevation of the associated runway endI.H.S, CONICAL SURFACE - respective runway end elevation - where significant difference exists betn. rwy end elevation of the order of 6m or more lower end elevation is the datum OHSAerodrome Elevation

Approach Surface

2250 M2% = 1: 502.5% = 1: 404000 MPLAN VIEWPROFILE VIEWApproach Surface45M150 M5.2% = 1: 19Approach Surface5%1:7

AGA Surfaces in Profile ViewGround LevelC/LTransitional Surface45MInner Horizontal SurfaceConical SurfaceOuter Horizontal Surface45M 300M 150M315M4000M2000M

145M

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