3. A back course marker normally indicates the
ILS back course final approach fix where approach
descent is commenced.

g. Compass Locator

1. Compass locator transmitters are often

situated at the MM and OM sites. The transmitters

have a power of less than 25 watts, a range of at least

15 miles and operate between 190 and 535 kHz. At

some locations, higher powered radio beacons, up to

400 watts, are used as OM compass locators. These

generally carry Transcribed Weather Broadcast

(TWEB) information.

2. Compass locators transmit two letter identi-
fication groups. The outer locator transmits the first
two letters of the localizer identification group, and
the middle locator transmits the last two letters of the
localizer identification group.

h. ILS Frequency (See TBL 1-1-4.)

TBL 1-1-4

Frequency Pairs Allocated for ILS

Localizer MHz Glide Slope
108.10 334.70
108.15 334.55
108.3 334.10
108.35 333.95
108.5 329.90
108.55 329.75

108.7 330.50

108.75 330.35

108.9 329.30
108.95 329.15
109.1 331.40
109.15 331.25
109.3 332.00
109.35 331.85
109.50 332.60
109.55 332.45
109.70 333.20
109.75 333.05
109.90 333.80
109.95 333.65
110.1 334.40
110.15 334.25
110.3 335.00
110.35 334.85
110.5 329.60
110.55 329.45

Localizer MHz Glide Slope
110.70 330.20
110.75 330.05
110.90 330.80
110.95 330.65
111.10 331.70

111.15 331.55

111.30 332.30

111.35 332.15

111.50 332.9

111.55 332.75

111.70 333.5

111.75 333.35

111.90 331.1
111.95 330.95

i. ILS Minimums

1. The lowest authorized ILS minimums, with
all required ground and airborne systems components
operative, are:
(a) Category I. Decision Height (DH)

200 feet and Runway Visual Range (RVR) 2,400 feet

(with touchdown zone and centerline lighting, RVR
1,800 feet), or (with Autopilot or FD or HUD, RVR
1,800 feet);

(b) Special Authorization Category I.
DH 150 feet and Runway Visual Range (RVR) 1,400
feet, HUD to DH;

(c) Category II. DH 100 feet and RVR 1,200

feet (with autoland or HUD to touchdown and noted

on authorization, RVR 1,000 feet);

(d) Special Authorization Category II with
Reduced Lighting. DH 100 feet and RVR 1,200 feet
with autoland or HUD to touchdown and noted on
authorization (touchdown zone, centerline lighting,
and ALSF-2 are not required);

(e) Category IIIa. No DH or DH below 100
feet and RVR not less than 700 feet;
(f) Category IIIb. No DH or DH below 50
feet and RVR less than 700 feet but not less than 150
feet; and

(g) Category IIIc. No DH and no RVR
limitation.
NOTE-
Special authorization and equipment required for
Categories II and III.