When an emergency evacuation is anticipated on water, what must N1 and N4 do first?

In an emergency evacuation anticipated on water, the primary concern is the safety and preparedness of passengers and crew before any other actions are taken. The correct course of action for N1 and N4 is to instruct passengers to adopt the brace position. This position is crucial as it minimizes injuries during the landing and prepares everyone for the immediate need to evacuate safely. By doing this first, crew members ensure that passengers are in the best possible position to handle the impact and are ready for a prompt evacuation once the doors are opened.

While other tasks such as checking equipment, opening doors, and signaling ABPs (Able-bodied Persons) are important aspects of the evacuation process, they follow the critical first step of preparing passengers for impact. The brace position holds priority because it directly affects passenger safety during the immediate emergency situation.