If a pilot experiences a two-way radio communication failure while in Class D airspace, what should he or she do with the transponder?

In the event of a two-way radio communication failure while operating in Class D airspace, the correct action is to set the transponder to code 7600. This communication failure code is specifically designated for situations where a pilot cannot establish or maintain communication with air traffic control (ATC). When a pilot sets the transponder to 7600, it alerts ATC and other aircraft in the vicinity that the aircraft is experiencing communication difficulties.

By doing so, the transponder helps ensure that the pilot remains visible to ATC, which enhances safety and allows for appropriate separation and traffic management, even though the pilot cannot communicate verbally. Other responses, such as leaving the transponder unchanged or turning it off, would not effectively communicate the emergency status to ATC, potentially leading to confusion and safety risks in the airspace. Setting the transponder to the correct code is a critical step in managing the situation effectively.