What must pilots read back when they receive clearance prior to an IFR departure that includes a SID?

When a pilot receives a clearance prior to an IFR departure that includes a Standard Instrument Departure (SID), the essential requirement is to read back the aircraft identifier and transponder code. This practice is crucial for ensuring that air traffic control (ATC) has accurately acknowledged the specific aircraft that is being cleared for departure, as well as the assigned transponder code, which is critical for radar identification and surveillance.

Reading back just the aircraft identifier and transponder code includes confirmation of the aircraft's unique identification and ensures that the pilot has the correct transponder code set in the aircraft's avionics. This focused acknowledgment minimizes the chance of confusion or miscommunication, especially in busy air traffic environments where multiple clearances may be issued simultaneously.

In contrast, while the full clearance details, departure airport, route, and flight rules are important pieces of information, they do not need to be read back in their entirety. ATC relies on brief confirmations of critical elements like the aircraft identifier and transponder code to efficiently manage departures, particularly when SIDs are involved.