After taking off, when should pilots switch to departure frequency?

The correct time for pilots to switch to departure frequency is upon passing pattern altitude. This is generally considered the appropriate procedure as it ensures that the pilot is clear of the traffic patterns associated with the airport and is in a position to safely transition to the next phase of flight.

At this point, the aircraft is usually at a safe altitude and can communicate effectively with approach or departure control, which can provide instructions regarding further navigation and ensure the safe flow of air traffic. Switching frequencies too early, such as immediately after takeoff, could lead to confusion and potential disruptions in communication, as the aircraft might still be in the active traffic flow pattern of the airspace surrounding the airport.

Other options relate to altitudes and phases of flight that do not align with standard operational procedures. For instance, switching at 500 feet may be too soon, while doing so before landing is not relevant since the focus transitions to approach and landing procedures at that time.