📘14 CFR §91.215 – ATC Transponder and Altitude Reporting Equipment
🚩 Overview
Transponders enhance radar detection by reporting your aircraft’s position and altitude to Air Traffic Control (ATC), increasing safety and collision avoidance capabilities. The FAA specifies when and where transponders must be used.
✅ Key Operational Requirements
📡 1. Required Equipment
Aircraft must have an operable ATC transponder with Mode C (altitude reporting) when operating:
Within Class A, B, and C airspace.
Within 30 nautical miles of the primary airport in Class B airspace (Mode C Veil).
Above Class B and C airspace up to 10,000 feet MSL.
At and above 10,000 feet MSL (excluding airspace below 2,500 feet AGL).
🚀 2. Operation of Equipment
The transponder must be operated continuously on the assigned ATC code, or squawk code, as directed by ATC.
If no ATC assignment is received, squawk the appropriate VFR code (1200).
🚫 3. Exceptions
Aircraft without an electrical system (e.g., balloons, gliders) or those not originally certified with an engine-driven electrical system may be exempt, but check current regulations carefully and communicate with ATC before flight.
🛩️ Example Scenario
You’re preparing a flight departing an airport located within the Mode C veil surrounding a busy Class B airport. Before takeoff, verify your transponder and altitude reporting equipment are operational, and set the appropriate ATC squawk code (typically 1200 for VFR if not otherwise assigned).
📌 CFI Pro Tips
Equipment Checks: Encourage students to include transponder checks in their preflight and run-up checklists, confirming correct codes and proper functioning.
Compliance and Awareness: Clearly explain Mode C veil requirements and emphasize planning ahead to ensure compliance with applicable airspace rules.
📚 Further Reading and Official References
14 CFR §91.215 (Full FAA Regulation): https://www.ecfr.gov/current/title-14/chapter-I/subchapter-F/part-91/subpart-C/section-91.215
FAA Aeronautical Information Manual (AIM) – Transponder Operation: https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap4_section_1.html
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