What is a caution to take when working around jet engines?

Maintaining at least a 30-foot distance from jet engines is crucial due to the intense forces and hazards present in their vicinity. Jet engines generate high-intensity heat and can produce powerful jet blast, which can reach considerable distances, potentially causing severe injury or damage. The distance requirement helps ensure that personnel remain safely out of the range of jet wash, which can displace objects and even knock a person off their feet. Furthermore, this distance allows for an awareness of the operational status of the engine, contributing to overall safety during airport operations.

The other options serve specific safety purposes but do not address the primary concern of avoiding the immediate hazards posed by jet engines. Wearing reflective gear aids visibility in busy airport environments, using signal flags can facilitate communication, and staying behind the aircraft may offer some safety, but none establish the critical safe distance needed to avoid the potentially dangerous effects of jet propulsion.