Which method is NOT used by an intercept aircraft to establish communication?

The method that is not typically used by an intercept aircraft to establish communication is the use of datalink signals via ADS-B In. While ADS-B (Automatic Dependent Surveillance–Broadcast) provides information about aircraft position and speed, it is primarily intended for surveillance and situational awareness rather than for direct communication.

Intercepted aircraft usually rely on more immediate and direct forms of communication to establish contact and convey instructions or intentions. Aerial visual signals, hand signals from the cockpit, and radio transmissions on emergency frequencies are established methods used in various scenarios, including intercept situations. These methods allow for clear communication and instructions among pilots, especially in critical situations where timely and direct communication is essential.

Thus, while ADS-B In enhances situational awareness, it is not primarily a tool for establishing communication between intercepting and intercepted aircraft.