FAA Ground School Practice Test

What equipment must an aircraft have to operate within Class C airspace?

1. 4096-code transponder only

2. Mode S transponder

3. 4096-code transponder with Mode C encoding

4. Standard altimeter

The correct answer is: 4096-code transponder with Mode C encoding

To operate within Class C airspace, an aircraft is required to be equipped with a 4096-code transponder that includes Mode C encoding. This specific transponder capability allows air traffic control to receive both the aircraft's squawk code and its altitude information. The inclusion of altitude data is essential for maintaining safe separation between aircraft, as Class C airspace is typically congested and involves a mix of IFR (Instrument Flight Rules) and VFR (Visual Flight Rules) traffic. A transponder that only transmits a squawk code without altitude encoding would not provide air traffic controllers with sufficient information to manage air traffic effectively, which is crucial in Class C airspace. Therefore, while standard altimeters and Mode S transponders are important for other operational contexts, they do not fulfill the specific requirement necessary for operation within Class C airspace like the 4096-code transponder with Mode C encoding does.