14 CFR 91.215 — ATC Transponder and Altitude Reporting Equipment and Use
Transponder with Mode C required in Class A, B, and C airspace, above Class B and C, and above 10,000 MSL (with exceptions).
Regulation Text
All airspace: Each person operating an aircraft in controlled airspace must operate with the applicable equipment: in Class A, B, and C airspace; in all airspace above the ceiling or lateral boundaries of Class B or C airspace up to 10,000 feet MSL; in all airspace at and above 10,000 feet MSL (except below 2,500 feet AGL); within 30 miles of certain primary airports in Class B airspace (the Mode C veil).
Note: This is an excerpt. Refer to the full regulation in eCFR for the complete text.
Plain-English Explanation
A transponder with Mode C (altitude reporting) is required in: Class A, B, and C airspace; within 30 nm of Class B primary airports (the Mode C veil); above the ceiling of Class B or C airspace up to 10,000 MSL; and at or above 10,000 feet MSL (except when below 2,500 AGL). You can fly in Class D, E, or G below 10,000 MSL without a transponder in most cases. If your transponder fails, you can request an ATC deviation to fly without it.
Tested On These Exams
Related Regulations
14 CFR 91.131 — Operations in Class B Airspace
Requires an explicit ATC clearance to enter Class B airspace, operative transponder with Mode C, and specific pilot certificate requirements.
§91.13014 CFR 91.130 — Operations in Class C Airspace
Requires two-way radio communication, operative transponder with Mode C, and ATC communication before entering Class C airspace.
§91.13514 CFR 91.135 — Operations in Class A Airspace
All operations in Class A airspace (18,000 MSL to FL600) must be conducted under IFR with an ATC clearance.
Pass your FAA exam in 30 days
Pilot Exam Crash Course
This regulation will be on your exam. Get 1,000+ practice questions with instant explanations. 94% of students pass on their first attempt.
50% off first month. Cancel anytime. 2,200+ questions.
Or subscribe for full access
All Exams, All Regulations — $7.49/mo
1,000+ questions covering all FARs. Cancel after you pass.
Cancel anytime. No commitment.