For ETOPS flight planning, what is the required RFFS for an alternate airport up to 180 minutes?

The correct choice reflects the standards set for ETOPS (Extended Operations) flight planning, particularly regarding the required Rescue and Fire Fighting Services (RFFS) for alternate airports. For flights with a diversion time of up to 180 minutes, the required RFFS is categorized under ICAO category 4. This category requires a specific level of firefighting capability and equipment to ensure that the airport can adequately respond to an aircraft emergency during operations that are further away from suitable airports.

ICAO category 4 airports are equipped with the necessary facilities and personnel to handle significant aircraft emergencies, which is essential for ensuring safety during extended operations where immediate assistance may be critical. Therefore, when planning ETOPS routes, ensuring that the alternate airports conform to at least this standard is vital for compliance with safety regulations and operational protocols.

In this context, the other categories either do not meet the minimum requirement for an alternate airport for 180-minute ETOPS or exceed what is necessary, as there are specific criteria established to ascertain the level of RFFS based on the duration and type of flight operation. Thus, selecting ICAO category 4 confirms adherence to these established safety standards.