The ILS Flashcards
The localizer provides
Lateral guidance
Localizer frequencies
Between 108.10 and 111.95 MHz
What is the width of the localizer
3-6 degrees
Usually 5 degrees total (2.5 each side full deflection)
The goal is for it to be 700’ wide over the threshold of the runway
How much more sensitive is the localizer compared to a VOR
4x more sensitive
What is the coverage of the localizer
First 10nm: 35 degrees coverage on each side
Up to 18nm: 10 degrees coverage on each side
Up to 4500’
What does the glide slope provide
Vertical guidance
What frequencies does the glide slope use
329.3 to 335 MHz (UHF) (automatically tuned with Localizer frequency)
What is the width of the glide slope
1.4 degrees
Full deflection is 0.7 degrees on each side
What is the range of the glide slope
Generally up to 10nm
What is the standard glide slope descent
3 degrees
What is a false glide slope
When you’re too high on your approach, your instruments may interpret a ‘false glideslope’ above the normal approach path
What do marker beacons provide
Range information
What frequency do the marker beacons transmit at
75 MHz
The outer marker beacon
4-7 miles out
Indicates the position at which
the aircraft should intercept the GS at the appropriate interception altitude ±50ft
BLUE “- - -“
The middle marker beacon
~3500ft from the runway
Indicates the approximate point where the GS meets the decision height
Usually 200ft above the touchdown zone elevation
AMBER “. - . -”
The inner marker beacon
Between the MM and runway threshold Indicates the point where the glide slope meets the DH on a CAT II ILS approach
WHITE “. . .”
The back course marker
Indicates the FAF on selected back course approaches
Not a part of the ILS approach
WHITE “.. ..”
The approach lighting system provides what
A means to transition from an instrument approach to a visual approach
How far does the ALS extend
2,400-3,000 feet for precision instrument runways
1,400-1,500 feet for non-precision instrument runways
