Which of the following is a necessary precaution when opening doors/hatches in flight?

Wearing a parachute or restraint harness is a necessary precaution when opening doors or hatches in flight due to the inherent risks involved. In the event that a door or hatch unexpectedly opens while the aircraft is in flight, it can create sudden decompression or airflow disturbances that could jeopardize the safety of the crew and passengers. A parachute provides an immediate means of escape in case of an emergency where leaving the aircraft becomes necessary. Additionally, a restraint harness is critical for ensuring that the individual remains secured to their seat or position in the cockpit, minimizing the risk of being thrown from the aircraft due to sudden changes in pressure or turbulence.

Other options do not adequately address the immediate safety risks associated with opening doors or hatches in flight. For instance, ensuring the aircraft is at cruising altitude might not prevent the dangers of sudden decompression or airflow issues. Waiting for clear skies won’t necessarily reduce the risks associated with the operation of doors or hatches, as issues can arise regardless of weather conditions. Coordinating with air traffic control, while important for communication and navigation, does not directly relate to personal safety while performing such actions in the cockpit.