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6/17/21 

AIM 

Aeronautical Information Manual 

Explanation of Changes 

Effective:  June 17, 2021 

a.  1

1

9. INSTRUMENT LANDING SYS-

TEM (ILS) 

This change is to edit the following text and add an 
additional figure to clarify that charted procedures 
with localizer coverage outside the Standard Service 
Volume (SSV) have been validated and approved by 
flight inspection. 

b.  1

1

13. USER REPORTS REQUESTED 

ON NAVAID OR GLOBAL NAVIGATION 
SATELLITE SYSTEM (GNSS) PERFOR-
MANCE OR INTERFERENCE 

1

2

4. PILOTS AND AIR TRAFFIC CON-

TROLLERS RECOGNIZING INTERFER-
ENCE OR SPOOFING 

The change to paragraph 1

2

4 is a complete rewrite. 

It was necessary to update information regarding uses 
and affected systems during GPS outages. The 
changes to paragraph 1

1

13 incorporate a paragraph 

title change, a correction to previous paragraph 
numbering, and a partial rewrite. This will aid in more 
extensive reporting requests to enable better analysis 
of outage events. 

c.  4

1

11. DESIGNATED UNICOM/MULTI-

COM FREQUENCIES 

Over the Continental United States and Coastal 
Waters 123.4 MHz and 123.45 MHz are reserved by 
the Federal Communications Commission (FCC) for 
stations individually licensed to commercial aircraft 
and accessory manufacturers to use as flight test 
frequencies. Aircraft may only communicate with 
their associated company ground stations and these 
frequencies may not be used for air

to

air 

communications of any sort. In order to bring 
attention to the proper usage of 123.4 MHz and 
123.45 MHz, this change adds these frequencies to 
TBL 4

1

3, Other Frequency Usage Designated by 

the FCC, along with the description of their use and 
the note that they are not for air

to

air communica-

tion. 

d.  4

2

3. CONTACT PROCEDURES 

In order to prevent confusion with the proper use of 
the frequency 123.4 MHz, this editorial change 
removes 123.4 as the generic ATC frequency used in 
this paragraph and the EXAMPLE following the 
paragraph, and substitutes a different generic ATC 
frequency. 

e.  5

1

1. PREFLIGHT PREPARATION 

5

1

2. FOLLOW IFR PROCEDURES 

EVEN WHEN OPERATING VFR 

7

1

2. FAA WEATHER SERVICES 

7

1

5. PREFLIGHT BRIEFING 

This change inserts language in the Aeronautical 
Information Manual that pilots do not need to call 
Flight Service in order to obtain a regulatory 
compliant briefing and encourages pilots to self

brief 

before calling a flight service station. 

f.  5

4

6. APPROACH CLEARANCE 

5

4

9. PROCEDURE TURN AND HOLD

 

IN

LIEU OF PROCEDURE TURN 

The proposed change adds subparagraph 5

4

6e8 

regarding arrival holding patterns and removes the 
current note after 5

4

9a5 which currently addresses 

arrival holding patterns inappropriately as hold

in

 

lieu of procedure turn. 

g.  5

4

23. VISUAL APPROACH 

This change updates Aeronautical Information 
Manual (AIM) guidance concerning multiple visual 
approaches to parallel runways at the same airport. 

h.  6

2

4. EMERGENCY LOCATOR TRANS-

MITTER (ELT) 

This change removes reference to the satellite 
monitoring of ELTs transmitting on 121.5 MHz and 
243.0 MHz. This update also focuses on the 
advantages of ELTs which transmit on 406 MHz. 

i.  6

4

3. REESTABLISHING RADIO CON-

TACT 

7

1

24. MICROBURSTS 

This change reflects the removal of the term ARINC 
and reflects the addition of new communication relay 

Explanation of Changes 

E of Chg