What should you do if the captain passes out at FL350?

If the captain passes out at FL350, the appropriate response is to put on your oxygen mask and declare an emergency. At that altitude, the aircraft is operating in a reduced oxygen environment, which can result in hypoxia for individuals who are not receiving supplemental oxygen. In this situation, the first step is to ensure you have adequate oxygen supply to maintain your own safety and cognitive function.

Declaring an emergency is critical because it raises awareness among air traffic control and other aircraft about the situation, enabling them to assist and provide priority handling if necessary. This can facilitate a quicker and safer response to stabilize the situation.

By taking these actions, you ensure that you are prepared to handle the situation effectively and prioritize the safety of both yourself and any passengers on board. Furthermore, aiding the captain requires addressing the immediate risk posed by altitude and the physiological effects of reduced oxygen, which makes utilizing oxygen essential for effective crew resource management.