What is the default transponder code for IFR aircraft flying below 18,000 feet ASL?

The default transponder code for IFR aircraft flying below 18,000 feet ASL is 1200. This code is used for VFR (Visual Flight Rules) operations; however, IFR flights typically have specific codes assigned to them for operational and safety purposes.

For IFR flights, air traffic control assigns a specific transponder code, often starting with a value that distinguishes it as an IFR flight. It’s important for pilots to understand the context of transponder codes, as they play crucial roles in identification and surveillance within controlled airspace.

The other codes mentioned are related to specific situations; for example, 7500 is reserved for hijacking situations, 7700 is for emergencies, and 2000 is sometimes used for general aviation flights subject to different classifications of airspace. The emphasis on 1200 as the default code signifies that it's imperative for pilots to be familiar with their transponder settings and requirements for both IFR and VFR operations.