What is an important safety measure when testing radar equipment on aircraft?

Ensuring the area is clear of people is crucial when testing radar equipment on aircraft due to the potentially harmful effects of radar emissions. Radar systems can emit powerful radio waves that may pose health risks to individuals in close proximity. By making sure the testing area is clear, you are minimizing the risk of exposure to these high-intensity signals, which could cause injury or health issues for anyone who might inadvertently be in the vicinity during the testing process.

Wearing protective eyewear, having a fire extinguisher nearby, and testing only at night may be relevant safety considerations in certain contexts, but they do not specifically address the direct risks associated with radar emissions during testing. Thus, keeping the area clear is the most relevant precaution to ensure safety.