What is a girt bar used for on an aircraft?

A girt bar is a crucial component used in the deployment of emergency slides on an aircraft. When the aircraft doors are opened in an emergency, the girt bar serves to attach the emergency slide to the aircraft. This mechanism ensures that the slide is securely anchored, allowing it to inflate and deploy properly for passenger evacuation. It is essential for the safety of all on board, providing a quick and effective exit route in an emergency situation.

The other options do not accurately describe the function of a girt bar. For example, luggage is secured using different mechanisms entirely and the function of holding cabin doors or supporting the cockpit roof involves different structural components of the aircraft that do not relate to the emergency slide system. Understanding the role of each equipment part is vital for ensuring passenger safety during emergencies.