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Attachment A Guidance Materials Supplementary to TP 312E, Aerodrome Standards and Recommended Pratices

5.  Strips

5.1  Shoulders

5.1.1  The shoulder of a runway or stopway should be prepared or constructed so as to minimize any hazard to an aeroplane running off the runway or stopway. Some guidance is given in the following paragraphs on certain special problems which may arise, and on the further question of measure to avoid the ingestion of loose stones or other objects by turbine engines.

5.1.2  In some cases, the bearing strength of the natural ground in the strip may be sufficient, without special preparation, to meet the requirements for shoulders. Where special preparation is necessary, the method used will depend on local soil conditions and the mass of the aeroplanes the runway is intended to serve. Soil tests will help in determining the best method of improvement (e.g. drainage, stabilization, surfacing, light paving).

5.1.3  Attention should also be paid when designing shoulders to prevent the ingestion of stones or other objects by turbine engines. Similar considerations apply here to those which are discussed for the margins of taxiways in the ICAO Aerodrome Design Manual, Part 2, both as to the special measures which may be necessary and as to the distance over which such special measures, if required, should be taken.

5.1.4  Where shoulders have been treated specially, either to provide the required bearing strength or to prevent the presence of stones or debris, difficulties may arise because of a lack of visual contrast between the runway surface and that of the adjacent strip. This difficulty can be overcome either by providing a good visual contrast in the surfacing of the runway or strip, or by providing a runway side stripe marking.

5.2  Objects on strips

Within the general area of the strip adjacent to the runway, measures should be taken to prevent an aeroplane's wheel, when sinking into the ground, from striking a hard vertical face. Special problems may arise for runway light fittings or other objects mounted in the strip or at the intersection with a taxiway or another runway. In the case of construction, such as runways or taxiways, where the surface must also be flush with the strip surface, a vertical face can be eliminated by chamfering from the top of the construction to not less than 30 cm below the strip surface level. Other objects, the functions of which do not require them to be at surface level, should be buried to a depth of not less than 30 cm.

5.3  Temporary hazards on runway strips

It is the responsibility of the aerodrome operator to ensure that the existence of all temporary obstructions or hazards within strips be made known as appropriate to pilots, either directly by Air Traffic Control or by NOTAM.

The following paragraphs give guidance on the operational implications and dealing with temporary hazards on runways strips.

5.3.1  Three zones alongside runways can be identified as follows:

ZONE I - This zone lies within 23 m of the runway edge where the runway code number is 2, 3, or 4; and, 21 m of the runway edge where the runway code number is 1.

ZONE II - This zone extends from the outer edge of Zone I to the edge of the graded strip. Refer to Chapter 3 for dimension of graded areas.

ZONE III - This zone applies only to nonprecision approach runways used in conditions of poor visibility or low cloud base. It extends outwards from the edge of the graded strip to the edge of the strip required for missed approaches, i.e. 150 m from the runway centre line.

5.3.2  Procedures for Zone 1.  No work should be permitted on a precision approach runway when the runway is in use. For a non-instrument or non-precision approach runway, work may take place in this zone on only one side of the runway at a time. The area of the obstacle should not exceed 9 m2, but narrow trenches may exceptionally be allowed up to 28 m2. Any obstacle permitted should be limited in height to provide propeller or pod clearance for the type of aircraft using the aerodrome, and in no case should the height exceed 1 m above the ground. Any piles of earth or debris which could damage aircraft or engines must be removed. Trenches and other excavations should be backfilled and compacted as soon as possible.

No plant or vehicles should operate in this zone when the runway is in use.

An aircraft immobilized in this zone would automatically require the closure of the runway.

5.3.3  Procedures for Zone 2.  No work should be permitted on a precision approach runway when the runway is in use. For a non-instrument or non-precision approach runway, the restrictions to be applied depend on the type of operation taking place and the weather conditions.

With a dry runway and not more than 15 Kt crosswind component for runways of code number 4, and 10 Kt cross-wind component for runways of code number 2 or 3, the following work may be permitted:

  1. Visual flight conditions:
     
    1. Unrestricted areas of construction, with the length of excavation or excavated material parallel to the runway being kept to a minimum. The overall height of excavated material should be limited to 2 m above the ground.
    2. All construction equipment should be mobile and kept within normal height limits.
    3. The runway may continue in use when an aircraft is immobilized in this zone.
  1. Instrument flight conditions:
     
    1. Unrestricted areas of construction, with the length of excavation or excavated material parallel to the runway being kept to a minimum. The overall height of excavated material should be limited to 2 m above the ground.
    2. All construction equipment should be mobile and kept within normal height limits.
    3. When an aircraft becomes immobilized in this zone, the runway should be closed.

5.3.4  Procedures for Zone 3.  There are no restrictions on the work in this area. However, care must be taken to ensure that the work and the vehicles associated with the work do not interfere with the operation of radio navigational aids.

Note - Contractor’s permanent and semipermanent plant and mobile equipment withdrawn form the strips should not infringe the transitional surfaces described in chapter 4.

5.3.5  Runway Ends.  In the case of work adjacent to the runway ends, the maximum possible use should be made of alternate runways or the displacement of the threshold so that the obstacle does not fall within the effective strip length or penetrate the associated approach surfaces. However, where landing distance may be critical, it may be safer to permit such an infringement near the runway end rather than displace the threshold.

5.3.6  Procedures during Navigation Aid Flight Inspection.  Notwithstanding the foregoing instruction contained in 5.3.2 and 5.3.3, a theodolite and radio equipped flight inspection technician may be permitted in either Zone I or Zone II during precision approach navigation aid flight inspection while a runway is in use. It is recommended that NOTAM and voice advisory be issued during flight inspections.

5.3.7  Pre-Construction Meeting.  It is an excellent practice for the contractor, airport operator and traffic control authority (where traffic control exists) to meet well in advance of the start of construction. This meeting can then consider such matters as discussed above, and agree on:

  1. means of control of construction vehicles so as to minimize interference with aircraft operations;
     
  2. scheduling of construction activities to conform as much as possible to periods of minimum aircraft activity; and
     
  3. disposal of excavated material, storage of construction material and equipment, and conditions of work site at the end of the period of work.

5.3.8  Procedures for Revising Declared Distances.  In the event that an unacceptable obstacle exists within the strip areas or associated clearway, the continued availability of the runway may be authorized at a restricted length, if the reduced distances available would be operationally usable by the type of traffic expected. The declared distances have a statutory application in aircraft operations and it is important that amendments are made when circumstances give a rise to their restrictions. See example in Figure 1, Appendix A.

The changes to the declared distances for a runway restricted in length by the presence of an obstacle are to be made as follows:

  1. Commencement of takeoff runs from the obstructed end. TORA may commence at the beginning of the usable runway.
     
  2. Termination of declared distances towards the obstructed end.

    TORA - terminates at the end of the usable runway.

    ASDA - terminates at the end of the runway or stopway if provided.

    TODA - terminates at the obstruction or at TORA plus 300 m (1,000 ft.), whichever comes first.

    LDA - terminates at the end of the usable runway.

5.3.9  Instrument Approach Procedures.  The presence of temporary obstructions and/or changes to the runway threshold may require an amendment to the instrument approach procedure. Details should be provided to the Certifying Authority.

5.3.10  Taxiway Obstructions.  In considering the acceptability of an obstruction near a taxiway the aerodrome operator will be guided by the type of aircraft using the airport and the availability of an alternative ground routing avoiding the affected length of taxiway. A clearance distance of whichever is the greater of 20% of wing span or 7.5 m (25 ft.) should be preserved between the obstruction and the wing tip of an aircraft on the taxiway centre line, when the aircraft is permitted to use that taxiway. If in doubt a marshaller should be positioned at the point and the pilot warned by radio when approaching the affected area.

5.3.11  Marking of Obstructions.  The marking by day and night of obstructed areas should be in accordance with the marking requirements of unserviceable areas of a runway, taxiway or other areas prescribed in Chapter 7. It will be appropriate by night, and possible by day also, to mark the perimeter of the obstruction itself if it is close to a taxiway, the continued use of which has been authorized. However, it will serve little purpose to a pilot landing or taking off, to mark either by day or night, an obstruction in a position which does not affect the continued use of the runway. Indeed, extraneous red lights may be misleading from the air and the pilot is only interested in seeing a pattern which clearly indicates the part of the runway which can be used.

5.3.12  Tall Obstruction (e.g. Cranes, etc.).  The responsibility for lighting and marking of obstructions rests with the aerodrome operator regardless of the owner of the obstruction. A certificate may be withheld or withdrawn if the requirements for lighting and/or marking are not met. Every attempt should be made to remove or lower the obstruction during the hours of darkness or during periods of idleness, i.e. weekends, etc. If this is not practicable, the obstruction should be marked at the top by one or more obstruction (red) lights. Day marking normally will not be required where the obstruction is painted in bright colours.

Date modified:
2010-05-20