How should you secure the boarding ladder if you need to leave the aircraft?

Securing the boarding ladder is important for safety and operational readiness, especially when there's a need to leave the aircraft. Stowing the ladder is essential as it prevents potential hazards, such as the ladder being knocked over or creating a tripping hazard for personnel in the vicinity.

By placing an 'X' in grease by the ladder, you are indicating to others that the aircraft is not to be boarded, and this visual cue helps maintain safety protocols around the aircraft. Stowing the ladder properly also ensures that it is not in a position where it can be damaged or create an obstruction.

Closing the cockpit, while an important step in other contexts, does not address the ladder's potential hazards directly. Leaving the ladder standing poses a risk of it being inadvertently hit or causing an accident. Placing it on the ground is also not a preferred solution, as it could create a tripping hazard or be misplaced. Therefore, securing the ladder and marking it with an 'X' is the best practice to ensure safety around the aircraft.