DH shall be published on instrument approach charts (IAC) of the concerned airfield. The pilot should follow the ILS guidance until the decision height (DH) is reached. It should not be expected that the glide path will provide guidance to the touchdown point on the runway.Īn approach may not normally be continued unless the runway visual range (RVR) is above the specified minimum. The glide path provided by the glide slope transmitter is arranged so that it flares from 5 to 8m (18 to 27ft) above the runway. The glide slope is normally usable to a distance of 10NM (it can be extended when requested). The glide path projection angle is normally adjusted to 3° above the horizontal plane so that it passes through the middle marker at about 60m/200ft and the outer marker at about 426m/1400ft.

It transmits a glide path with a beam width of 1.4°. The glide scope transmitter is located between 230m/750ft and 380m/1250ft from the approach end of the runway and offset between 75m/250ft and 198m/650ft from the runway centre line. The glide slope frequency is usually paired with the localizer frequency as the pilot enters only the localizer frequency in the aircraft instruments. The glide path radiates its signal only in the direction of the localizer front course. The glide slope transmitter operates on one of 40 ILS channels within the ultra-high frequency (UHF) band from 329.15 MHz to 335 MHz.

Ils localizer antenna