What communication method is necessary for a helicopter transiting under Special VFR regulations?

For a helicopter transiting under Special VFR regulations, two-way radio communication is essential. Special VFR allows pilots to operate in weather conditions below the established minimums for visual flight rules (VFR), but it requires maintaining communication with air traffic control (ATC). This communication is crucial for safety, as it ensures that the pilot is aware of other air traffic in the vicinity and can receive instructions from ATC for safe navigation.

In this context, visual signals are insufficient because they don't ensure reliable communication or confirm ATC instructions. Cellphone communication is not suitable for flight operations as it cannot provide the immediate, situational awareness required in a busy airspace environment. GPS tracking, while useful for navigation, does not substitute for the need for direct communication with air traffic controllers and does not fulfill the regulatory requirements for operating under Special VFR. Therefore, two-way radio communication is the only appropriate method for ensuring safety and compliance while conducting operations under these regulations.