GM1 ADR.OPS.C.015(b);(f) Maintenance of visual aids and electrical systems

LIGHTING SYSTEMS

GROUND CHECKS — GENERAL

The ground checks of the lighting system includes a set of different actions that would need to be undertaken at different intervals. These checks include but are not limited to the following:

(a) broken lights or parts of the unit;

(b) condition of filters;

(c) corrosion;

(d) cleanness;

(e) tightening of fasteners of units;

(f) alignment of lights;

(g) presence of moisture/water;

(h) electrical connections of lights; and

(i) condition of structure and the foundation of each unit.

GROUND CHECKS —VASIS

VASIS are used in order to provide correct visual glide slope indication to the flight crews in all variable weather conditions, by day and by night. It is therefore imperative that the maintenance programme ensures the correct alignment of the system, as well as its serviceability at all times. In order to achieve this, a suitable maintenance programme, including the correct frequency of ground checks, needs to be developed and implemented.

During daily checks, the general condition of each unit is checked to determine the following:

(a) all lights are lighted and illuminated evenly;

(b) there is no evidence of apparent damages;

(c) the change from red to white is coincident for all elements in a unit; and

(d) the lenses are not contaminated.

Regarding the alignment of VASIS, the individual unit setting angles are checked by means of angular measurement, in accordance with the manufacturer’s instructions. A visual comparison between all the units in the system set at the same angle may be used to identify a unit in which there is a misalignment between the optical system and the datum plate. The cause of any misalignment of this nature needs to be ascertained and corrected before any adjustment is made to the setting angles.

Where the ground where the VASIS are installed is less stable, or intense weather phenomena such as frost, heavy rain or drought take place, or variations in weather occur, the aerodrome operator needs to adjust the ground checks of the VASIS, as such phenomena may lead to misalignment of the VASIS. In this way, gross alignment errors may be prevented.

FLIGHT CHECKS

Flight checks for precision approach runways aremore frequent and detailed than other runway types.

Lights are checked for failures and alignment, while the VASIS are also be checked for correct approach slope, and compatibility with the non-visual aids, if available. Moreover, the balance of light intensity, at all intensity settings, needs to be checked.

During daylight flight checks, an assessment of the markings needs also to take place.

Flight checks may be arranged to be conducted with the planned calibration flights of the no-visual aids. The opportunity is also be taken to identify any confusing or misleading lights in the aerodrome surroundings.

Further guidance on how to conduct a flight check and the items that need to be checked during the flight check may be found in Chapter 5 of Part 8 ‘Airport Operational Services’ of ICAO Doc 9137 ‘Airport Services Manual’, and in Chapter 8 of Part 4 ‘Visual Aids’ of ICAO Doc 9157 ‘Aerodrome Design Manual’.