Chapter

21

Aerodrome Lighting

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Lighting Aerodrome 21

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Aerodrome Lights

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21.14 Simple Approach Lighting System. A simple approach lighting system consists of a row of lights on the extended centre line of the runway extending, whenever possible, over a distance of not less than 420 m from the threshold with a row of lights forming a crossbar 18 m or 30 m in length at a distance of 300 m from the threshold. The lights forming the crossbar shall be as nearly as practicable in a horizontal straight line at right angles to, and bisected by, the line of the centre line lights. This type of system is used on a non-instrument runway and may be used on a non-precision instrument runway.

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21.15 Precision Approach CAT I Lighting System. A precision approach category I lighting system consists of a row of lights on the extended centre line of the runway extending, wherever possible, over a distance of 900 m from the runway threshold. If the length is less than 900 m (which on a 3° glide path coincides with CAT I system minima - 200 ft) it is possible that an aircraft may not be over the approach lighting at DH. The 5 crossbars are 150 m apart and form three segments: the inner segment (0 - 300 m); the middle segment (300 - 600 m); and the outer segment (600 - 900 m). Any ILS or MLS azimuth antenna protruding through the plane of the lights will be treated as an obstacle and marked and lit accordingly.

Lighting Aerodrome 21

Figure 21.2 CAT I Calvert 5 bar and centre line system

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21.16 ICAO Precision Approach CAT I Lighting System. In this arrangement, the centre line is in the form of barrettes with only one crossbar at 300 m from the threshold. Again, the centre line should be 900 m in length. The centre line may be augmented with strobe lights that ‘ripple’ towards the threshold from the start of the centre line. The visibility of the threshold may be enhanced by the use of wing strobes (rotating).

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21.17 Precision Approach Category II/III Lighting System. At those aerodromes where Cat II and III approaches are conducted more complex approach lighting system are installed to enhance the possibility of the pilot achieving the visual criteria at DH to complete the landing. The systems used are various but all are based on either the Calvert 5 bar and centre line system, or the ICAO barrette system. Both systems should be 900 m long and provide some element of attitude information. In both the Calvert and the ICAO systems the inner segment (0 - 300 m from the threshold) is augmented by the supplementary approach lighting. This consists of replacing the centre line of the Calvert system with barrettes and adding red wing barrettes to both systems. The effect is to enhance the visibility and conspicuity of the inner segment. DH for Cat II is not lower than 100 ft which equates to 300 m from the threshold (assuming the pilot crosses the threshold at 50 ft).

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Figure 21.4 Approach & runway Cat II/III lighting system

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© L ten Hoopen

Figure 21.6 Calvert Cat II/III system at Cork

21.18 Precision Approach Path Indicators (PAPI). As an additional aid to a precision approach, glide path guidance is provided during the visual phase (after DH) by the PAPI lighting system. This consists of 4 light units showing either red or white light through precision defined angles. Each light unit is set to a different mid angle and below that angle shows red and above shows white. The overall effect is to give a reference to the median angle which is set to the required glide path (e.g. 3°). ICAO define PAPI as “A wing bar of 4 lights uniformally spaced”.

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Installation by: Godfrey Systems International, Inc

Figure 21.7 Precision approach path indicators (PAPI)

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21.19 PAPI Indications. The possible combinations of the 4 light sets give 5 different indications relating to the aircraft position (correctly, the pilot’s eye) with respect to the defined glide path.

PAPIs

Figure 21.8 PAPI indications

21.20 CirclingApproach. Wheretherunwayisusedforcirclingapproaches(visualmanoeuvring circling) a PAPI set is placed on either side of the runway. Normally there would only be one set on the left hand side. This allows the pilot to use the PAPI wing bars as a horizontal reference for aircraft attitude during the later part of the circling manoeuvre.

21.21 Minimum Eye Height (MEHT). If the PAPI system was located exactly at the threshold of the runway, and the pilot flew a visual approach keeping the aircraft exactly at the ‘on glide path’ position, the wheels of the aircraft would hit the ground before the aircraft reached the threshold. The distance before the threshold where the wheels hit the ground would be a function of the distance from the pilot’s eye to the bottom of the undercarriage. To overcome

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