Before the RCC can begin search and rescue operations, what must be issued?

The correct answer is the issuance of an ALNOT, which stands for Alert Notice. An ALNOT is a critical notification issued in response to a missing aircraft or vessel and signals to search and rescue (SAR) organizations that immediate action is required to locate the entity in distress. This alert helps to mobilize the appropriate resources and coordinate the rescue efforts.

In the context of search and rescue operations, the issuance of an ALNOT serves as an official declaration that there is a need for assistance, thereby triggering search protocols. This notice includes necessary details about the incident and the last known position, allowing search and rescue teams to organize their efforts effectively.

The other options, while related to air traffic and search protocols, do not specifically initiate SAR operations like the ALNOT does. An INREQ (Information Request) is used to request information about an aircraft's whereabouts, but it does not indicate the urgency of a situation or prompt a rescue operation. A Request for Assistance may not have the official status needed to mobilize resources effectively. Search Authorization, while important, typically comes after the initial alert. Thus, the ALNOT is the most appropriate and necessary step before search and rescue can begin.