Table 4 THAAD launcher Practice Test

The key safety rule here is that certain systems are only safe to approach when they are not armed. When the red ARM indicator is illuminated, the launcher is in an armed state and could initiate a firing sequence. That means any approach could trigger dangerous activity or release hazardous energy, posing serious risk to personnel and equipment. Therefore, you must never approach while that red light is on, and you should only move in after proper disarming and clearance procedures have been followed.

The other conditions describe states where the system isn’t ready to operate (power status, initialization, or targeting checks). While those states also require caution, the explicit reason for a blanket prohibition on approaching is the armed condition indicated by the red light.