What are Runway Turn Pad Lights?

Runway turn pad lights are fixed green lights that guide an aeroplane through a 180-degree turn and onto the runway centre line.

Definition

ICAO defines a runway turn pad as a defined area on a land aerodrome next to a runway. Aeroplanes use it to complete a 180-degree turn on a runway. ICAO and EASA give the lights one purpose. They give continuous guidance to an aeroplane that turns on the pad and then lines up with the runway centre line (ICAO 5.3.19.1, CS ADR-DSN.M.725(a)).

The turn pad page covers the pad itself. It gives the size, the wheel clearance, the strength and the marking. This page covers the lights only.

What the standards require

ICAO writes the low visibility case as a Standard (“shall”). EASA writes “should” for every row, and uses 350 m. EASA leaves GM1 ADR-DSN.M.725 blank.

The isocandela figures that these rules name carry the titles of taxiway centre line diagrams. Figure A2-13 is for 15 m spacing, and Figure A2-14 is for 7.5 m spacing (ICAO). Figure U-17 is for 15 m spacing, and Figure U-18 is for 7.5 m spacing (EASA). A turn pad light therefore has the beam of a taxiway centre line light at the same spacing. This page gives no intensity value, because the value sits in the figure.

Where the lights stand

The lights follow the turn pad marking. ICAO and EASA say that the marking is yellow (ICAO 5.2.1.5, CS ADR-DSN.L.520(b)). The marking curves from the runway centre line into the pad, so the lights curve with it.

• On the marking. Each light stands on the marking line. It may sit up to 30 cm to one side where it cannot stand on the line.
• Straight section. The lights are at most 15 m apart.
• Curved section. The lights are at most 7.5 m apart.

Turn pad lights and taxiway edge lights

A turn pad that is used at night usually has two sets of lights.

Sources: ICAO 5.3.19, 5.3.18.1, 5.3.18.5 and 5.3.18.6. EASA CS ADR-DSN.M.725 and M.720(a)(1), (b)(3) and (b)(4).

ICAO requires edge lights at the edges of a turn pad for night use. EASA recommends them. Both allow an exception where surface illumination or other means give adequate guidance. The taxiway edge light page covers the blue lights.

How a turn pad light differs from a centre line light

Both are fixed green lights, and both use the taxiway centre line isocandela diagrams. They differ in what they mark. A taxiway centre line light marks a taxi route. A turn pad light marks the curved path on the pad, which ends on the runway centre line.

Maintenance

For taxiway lights, EASA sets numeric maintenance objectives only for centre line lights and for stop bars at a runway holding position. Both apply to use below 550 m runway visual range. ADR.OPS.C.015(b) gives no numeric objective for runway turn pad lights.

The test for an unserviceable light still applies to each one. A light is unserviceable if its main beam average intensity is below 50 percent of the specified value. It is also unserviceable if its filter is missing or damaged, or if the beam has the wrong colour (ADR.OPS.C.015(c)).

What an inspection checks

An inspection of a turn pad that is used at night covers these items:

• Each turn pad light is lit and shows green.
• The lights follow the marking, with no light more than 30 cm off it.
• The spacing is within 15 m on the straight section and 7.5 m on the curve.
• The lights face the aeroplane that approaches the pad.
• The blue edge lights stand at the edge, at most 30 m apart.

A drone flight can record whether each light is lit, its colour and its position. TarmacView’s taxiway lights inspection does this for the taxiway network. It does not measure intensity in candela.