How many lock indicators are there on the door of the aircraft?

The correct answer indicates that there are two lock indicators on the door of the aircraft. The purpose of having two lock indicators is to provide a clear and reliable method for crew members to visually verify that the door is correctly locked and secured before the aircraft takes off or after landing. This dual-indicator system enhances safety by reducing the possibility of human error, ensuring that both indicators must be checked and confirmed for the door to be deemed secure. An understanding of these indicators is crucial for ground staff and cabin crew in maintaining operational safety and adherence to safety protocols.