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6/17/21 

AIM 

110.15 

334.25 

110.3 

335.00 

110.35 

334.85 

110.5 

329.60 

110.55 

329.45 

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. 

j.  Inoperative ILS Components 

1. Inoperative localizer. 

When the localizer 

fails, an ILS approach is not authorized. 

2.  Inoperative glide slope. 

When the glide 

slope fails, the ILS reverts to a non

precision 

localizer approach. 

REFERENCE

 

See the inoperative component table in the U.S. Government Terminal 
Procedures Publication (TPP), for adjustments to minimums due to 
inoperative airborne or ground system equipment. 

k.  ILS Course Distortion 

1. 

All pilots should be aware that disturbances to 

ILS localizer and glide slope courses may occur when 
surface vehicles or aircraft are operated near the 
localizer or glide slope antennas. Most ILS 
installations are subject to signal interference by 
either surface vehicles, aircraft or both. ILS 
CRITICAL AREAS are established near each 
localizer and glide slope antenna. 

2. 

ATC issues control instructions to avoid 

interfering operations within ILS critical areas at 
controlled airports during the hours the Airport 
Traffic Control Tower (ATCT) is in operation as 
follows: 

(a) Weather Conditions. 

Official weather 

observation is a ceiling of less than 800 feet and/or 
visibility 2 miles. 

(1)  Localizer Critical Area

.  Except for 

aircraft that land, exit a runway, depart, or execute a 
missed approach, vehicles and aircraft are not 
authorized in or over the critical area when an arriving 
aircraft is inside the outer marker (OM) or the fix 
used in lieu of the OM. Additionally, whenever the 
official weather observation is a ceiling of less than 
200 feet or RVR less than 2,000 feet, do not authorize 
vehicles or aircraft operations in or over the area 
when an arriving aircraft is inside the MM, or in the 
absence of a MM, 

½

 mile final. 

(2)  Glide Slope Critical Area. 

Do not 

authorize vehicles or aircraft operations in or over the 
area when an arriving aircraft is inside the ILS outer 
marker (OM), or the fix used in lieu of the OM, unless 
the arriving aircraft has reported the runway in sight 
and is circling or side

stepping to land on another 

runway. 

Navigation Aids 

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