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6/17/21 

AIM 

(c) 

Class E airspace at and above 10,000 feet 

MSL within the 48 contiguous states and the District 
of Columbia, excluding the airspace at and below 
2,500 feet AGL; 

(d) 

Within 30 miles of a Class B airspace 

primary airport, below 10,000 feet MSL (commonly 
referred to as the “Mode C Veil”); 

(e) 

For ADS

B Out: Class E airspace at and 

above 3,000 feet MSL over the Gulf of Mexico from 
the coastline of the United States out to 12 nautical 
miles. 

NOTE

 

The airspace described in (e) above is specified in 14 CFR 
§ 91.225 for ADS

B Out requirements. However, 14 CFR 

§ 91.215 does not include this airspace for ATC 
transponder requirements. 

(f) 

Transponder and ADS

B Out require-

ments do not apply to any aircraft that was not 
originally certificated with an electrical system, or 
that has not subsequently been certified with such a 
system installed, including balloons and gliders. 
These aircraft may conduct operations without a 
transponder or ADS

B Out when operating: 

(1) 

Outside any Class B or Class C airspace 

area; and 

(2) 

Below the altitude of the ceiling of a 

Class B or Class C airspace area designated for an 
airport, or 10,000 feet MSL, whichever is lower. 

3. 

14 CFR Section 99.13 requires all aircraft 

flying into, within, or across the contiguous U.S. 
ADIZ be equipped with a Mode C or Mode S 
transponder. Balloons, gliders and aircraft not 
equipped with an engine

driven electrical system are 

excepted from this requirement. 

REFERENCE

 

AIM, Chapter 5, Section 6, National Security and Interception 
Procedures. 

4. 

Pilots must ensure that their aircraft transpon-

der/ADS

B is operating on an appropriate 

ATC

assigned VFR/IFR code with altitude reporting 

enabled when operating in such airspace. If in doubt 
about the operational status of either feature of your 
transponder while airborne, contact the nearest ATC 
facility or FSS and they will advise you what facility 
you should contact for determining the status of your 
equipment. 

5. 

In

flight requests for “immediate” deviation 

from the transponder requirements may be approved 

by controllers only for failed equipment, and only 
when the flight will continue IFR or when weather 
conditions prevent VFR descent and continued VFR 
flight in airspace not affected by the CFRs. All other 
requests for deviation should be made at least 1 hour 
before the proposed operation by contacting the 
nearest Flight Service or Air Traffic facility in person 
or by telephone. The nearest ARTCC will normally 
be the controlling agency and is responsible for 
coordinating requests involving deviations in other 
ARTCC areas. 

6. 

In

flight requests for “immediate” deviation 

from the ADS

B Out requirements may be approved 

by ATC only for failed equipment, and may be 
accommodated based on workload, alternate surveil-
lance availability, or other factors. All other requests 
for deviation must be made at least 1 hour before the 
proposed operation, following the procedures 
contained in Advisory Circular (AC) 90

114, 

Automatic Dependent Surveillance

Broadcast Oper-

ations. 

g.  Transponder/ADS

B Operation Under Vis-

ual Flight Rules (VFR) 

1. 

Unless otherwise instructed by an ATC 

facility, adjust transponder/ADS

B to reply on Mode 

3/A Code 1200 regardless of altitude. 

NOTE

 

1. 

Firefighting aircraft not in contact with ATC may 

squawk 1255 in lieu of 1200 while en route to, from, or 
within the designated fire fighting area(s). 

2. 

VFR aircraft flying authorized SAR missions for the 

USAF or USCG may be advised to squawk 1277 in lieu of 
1200 while en route to, from, or within the designated 
search area. 

3. 

Gliders not in contact with ATC should squawk 1202 in 

lieu of 1200. 

REFERENCE

 

FAA Order JO 7110.66, National Beacon Code Allocation Plan

.

 

2. 

When required to operate their transponder/ 

ADS

B, pilots must always operate that equipment 

with altitude reporting enabled, unless otherwise 
instructed by ATC or unless the installed equipment 
has not been tested and calibrated as required by 
14 CFR Section 91.217. If deactivation is required, 
turn off altitude reporting. 

3. 

When participating in a VFR formation flight 

that is not receiving ATC services, only the lead 
aircraft should operate their transponder and ADS

Out. All other aircraft should disable transponder and 

Services Available to Pilots 

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