FAA Military Competency Practice Exam

What is the minimum altitude at which an operable coded transponder with Mode C is required in the contiguous U.S.?

1. 5,000 feet MSL

2. 10,000 feet MSL

3. 2,500 feet AGL

4. 3,500 feet MSL

The correct answer is: 10,000 feet MSL

The requirement for an operable coded transponder with Mode C in the contiguous U.S. is set to provide enhanced situational awareness and safety, particularly in busy airspace. The minimum altitude at which this equipment becomes necessary is 10,000 feet MSL (Mean Sea Level). At or above this altitude, a transponder with Mode C helps air traffic control track aircraft and maintain safe separation in a variety of air traffic scenarios. This regulation is critical for operations in and around busy terminal airspace, where the likelihood of encountering other aircraft increases significantly. Additionally, Mode C transponders provide altitude information, which is essential for ATC to ensure vertical separation between aircraft. Below 10,000 feet MSL, there are specific exceptions and circumstances, but in general, for safety and efficiency in higher traffic environments, the requirement is set at this altitude for the transponder to be operational.