What indicates that a Phase IV MCD is closed properly?

The indication that a Phase IV MCD (Main Cargo Door) is closed properly is demonstrated by the alignment of all green lines and that the door lock indicator shows green. This means that the door has not only been closed but also securely locked in its designated position, ensuring that it is safe for operation. The green lines represent visual cues that confirm all mechanisms involved in the locking process are functioning correctly.

In contrast, simply having all doors visible, any red light off, or hearing the sound of the locking mechanism does not comprehensively confirm that the door is closed properly. These factors could indicate partial closure or readiness but do not verify the complete lock and alignment necessary for the MCD's safety and operational integrity. A visual confirmation of the alignment and lock status provides assurance of the MCD’s proper and safe closure.