ILS components

Question 1

Localizer

Answer 1

Broadcasts over VHF between 108.1-111.95MHz

Between 3-6 degrees wide (2.5 full deflection to each side) 700 ft at threshold and 4 times more sensitive than a vor

Coverage is 35 degrees either side for the first 10nm and up to 10 degrees up to 18nm from the antenna up to 4500ft

Question 2

Glide slope

Answer 2

Vertical guidance

1.4 degrees width and 0.7 either direction
up to 10nm range
3 degrees slope
note false glide slope errors

Question 3

Marker Beacons

Answer 3

Range information

Outer Marker- 4-7 miles out. Indicate the position where the plane should intercept the GS. Flashes Blue

Middle Marker- 3500ft from the runway. Indicates the apporximate point where the GS meets the decision height. Usually 200ft above the touchdown zone elevation. Flashes Amber

Inner marker- Between the MM and runway threshold. Indicates the point where the glide slope meets the DH on a CATII ILS approach. Flashes White

Back course marker- Indicates the FAF on selected back course approaches. Not part of the ILS approach. White