What procedural step is mandatory before taking off with a potential medical issue on board?

Before taking off with a potential medical issue on board, it is critical to check the feasibility of an emergency landing. This step ensures that in the event of a medical emergency during flight, the flight crew has identified viable landing options to provide immediate medical assistance. Thoroughly assessing emergency landing sites is a fundamental safety measure, ensuring that if the situation escalates, the aircraft can reach the ground safely and quickly. This procedure reflects the priority given to passenger safety, facilitating prompt action should an urgent medical response be required during the flight.

While confirming seating arrangements, ensuring medical kits are onboard, and notifying flight attendants are important, these actions do not directly address the need for emergency preparedness in case of a medical crisis. The feasibility of an emergency landing directly impacts the ability to respond effectively to in-flight emergencies.