AERODROME TRAINING COURSE – MODULE 4Control of Obstacles

CONTROL OF OBSTACLES

Learning Outcome

On completion of this module students will be able to explain the requirements for controlling obstacles to facilitate an airport operation.

• With access to reference material detail the specific dimensions of an Airports Obstacle Limitation Surfaces

Obstacle Limitation - Obstacle Assessment - Obstacle Protection Surfaces

• Explain the basic requirements and inter-relationship between :-

They will be able to:

Obstacle Limitation Surfaces (ANNEX 14)

Obstacle Assessment Surfaces (PANS OPS Doc 8168)

• ANNEX 14 Obstacle Limitation Surfaces

The broad purpose of these surfaces is to define the volume of airspace around aerodromes to be maintained free from obstacles so as to permit the intended aeroplane operations at the aerodrome to be conducted safely and to prevent the aerodromes from becoming unusable by the growth of obstacles. This is achieved by establishing a series of OLS that define the limits to which objects may project into the airspace

• PANS OPS Obstacle Assessment SurfacesThese surfaces are intended for use by procedure designers for the

construction of instrument flight procedures and for specifying minimum safe altitudes/heights for each segment of the procedure

• ANNEX 14

• PANS OPS DOC 8168

• Instrument Approach Surfaces • Circling • Departure Surfaces

Annex 14 Obstacle Limitation Surfaces

Obstacle Assessment Surfaces

Annex 14 Obstacle Protection Surface

• for VASIS/PAPI

•Transitional Surfaces•Inner Horizontal•Conical•Outer Horizontal•Approach•Take-off climb •Balked Landing (Precision)•Obstacle Free Zone (Precision Cat 2 & 3)

ANNEX 14 OLS

Obstacle LimitationObstacle Limitation

SurfacesSurfaces

Purple –Inner Horizontal, conical, Outer horizontal

Green Approach

Red Take-off climb

OBSTACLE LIMITATION SURFACES

OLS DIMENSIONS

Annex 14 Transition OLS

Transition OLS

Annex 14 Approach Surface

Annex 14 Approach Surface

Annex 14 Transition and Approach Surfaces

Inner Horizontal and Conical

Inner Horizontal surface 4000m radius from Reference Point 45m above a runway elevation datum

Conical surface from Horizontal surface 45m at slope of 5% to 100m

Refer AerodromeServices Manual Part 6

Where surfaces overlap the lower surface should be regarded as dominant

Annex 14 Take-off Surfaces Code 3 & 4

Annex 14 Take-off 1.6%

60m from Runway End*

6480m

*The take-off climb surface starts at the end of the clearway if the clearway length exceeds the specified distance. Refer Annex 14 Table 4-2

Annex 14 Take-off 2.0%

*The take-off climb surface starts at the end of the clearway if the clearway length exceeds the specified distance. Refer Annex 14 Table 4-2

ANNEX 14 Obstacle Free Zone

Obstacle Free Zone

• Obstacle Free Zone is established for Precision Category I (recommended), II, III operations

• Inner approach, Inner Transitional and Balked Landing surfaces create the Obstacle Free Zone for precision approach operationsReference: Description of ANNEX 14 4-3

Doc 9137 Part 6

Obstacle Free Zone

ANNEX 14 Obstacle Protection

Surface

ANNEX 14 Figure 5 -20

Obstacle protection surface for visual approach slope indicator system

ANNEX 14 Figure 5 -20

Dimensions and slopes of the obstacle protection surfaces

PANS OPSSURFACES

OCA/H for Visual manoeuvring (Circling)

Aircraft Radius from Thres Obstacle clearance Lowest OCH above Aerodrome Category (R) m

A 3.12 90 120(394ft)B 4.90 90 150(492ft)C 7.85 120 180(591ft)D 9.79 120 210(689ft)E 12.82 150 240(787ft)

PANS OPS 8168Circling Area

PANS OPS 8168VOR Approach surfaces

Relationship between different surfaces1 in 7 Side Transition, Inner Horizontal and Conical, Annex 14 Approach, VOR Approach

PANS OPS 8168Basic ILS obstacle assessment surfaces

ILS Collision Risk Model

Visual Segment Surface•All new straight-in instrument approach procedures published on or after 15 March 2007 shall be protected for obstacles in the visual segment. Straight-in instrument approach procedures published before 15 March 2007 shall be protected in the visual segment by means of the VSS after the periodical review of the procedure, but not later than 15 March 2012.

Dimensionsa base width of 300 m (150 m either side of the extended runway centreline) for a Code 3 and 4 runway and 150 m (75 m either side of the extended runway centreline) for Code 1 and 2, originating 60 m prior to the runway threshold, splaying 15 per cent on either side of the extended runway centreline, and terminating at the point where the height of the surface reaches the OCH

where the final approach course is offset and intersects the extended runway centreline, the splay on the side closest to the final approach course is increased by the offset angle. Vertically, the VSS originates at the runway threshold height and has a slope of 1.12 degrees less than the promulgated approach procedure angle

PANS OPS 8168Departure Surface

Departure 2.5% Obstacle assessment surfaceto protect aircraft climbing at 3.3%

Annex 14 Take-off surfaces with PANS OPS 8168 Departure Surface

3D view of Take-off OLS Annex 14 surface showing penetration of terrain

OLS Existing with structures included

3D modelling used to highlite proposed structures (RED) are below proposed raised OLS (yellow) but existing structures (BLUE) penetrate this surface

VOR/DME approach surface showing Nil penetration of obstacles

Initial Approach surfaces

Intermediate Approach surfaces

PRACTICAL EXERCISES

1. Calculate the height that an obstacle can be erected above an instrument runway precision Code 4 given: on extended centreline distance from threshold 4000m?

2. What OLS will control the height of an obstacle to be erected adjacent to midpoint of a Code 4 instrument runway at 320m for runway centreline?