AIM 8/15/19  1/30/20 2. In general, the CFRs require aircraft to be equipped with an operable Mode C transponder and ADS − B Out when operating: (a) In Class A, Class B, or Class C airspace areas; (b) Above the ceiling and within the lateral boundaries of Class B or Class C airspace up to 10,000 feet MSL; (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. 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. 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 requirement s  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. 1. Unless otherwise instructed by an ATC facility, adjust transponder/ADS − B to reply on Mode 3/A Code 1200 regardless of altitude. 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. 2. When required to operate their transponder/ ADS − B, pilots must always operate that equipment REFERENCE − FAA Order JO 7110.66, National Beacon Code Allocation Plan . NOTE − g. Transponder/ADS − B Operation Under Vis- ual Flight Rules (VFR) NOTE − AIM, Chapter 5, Section 6, National Security and Interception Procedures REFERENCE − 4 − 1 − 17 Services Available to Pilots