At what point should the ELS be turned on during a time-available evacuation?

The correct answer emphasizes the importance of preparing for a safe and efficient evacuation during critical phases of flight. Activating the Emergency Locator System (ELS) at two minutes to landing is crucial because it allows for optimal readiness in the event an evacuation becomes necessary upon landing. This timing ensures that rescue and emergency services are alerted and can be ready to act immediately, enhancing passenger safety and response efficiency.

In contrast, turning on the ELS at the start of the boarding process or immediately after takeoff does not align with the protocol that dictates activating emergency systems closer to when evacuation procedures might actually be required. During taxiing is typically a stable phase of flight where any emergencies leading to an evacuation would be less likely, thereby making the timing less relevant and potentially counterproductive. Therefore, activating the system specifically two minutes before landing strikes an appropriate balance between preparedness and operational safety.