What is a safe distance when approaching a helicopter that has just taken off?

The safe distance when approaching a helicopter that has just taken off is best described as "only when directed by flight personnel." Helicopters are particularly hazardous due to their rotors, which can create powerful down drafts, and the potential for debris to be lifted into the air. Additionally, the pilot or crew is trained to ensure the environment is safe for approach, so they will provide the appropriate signals or directions.

Approaching a helicopter without the guidance of flight personnel could expose an individual to unnecessary risk. Aircrafts have specific protocols for safety, which include not approaching until given clear communication from the personnel on board. This emphasizes the importance of adhering to established safety guidelines and trusting the expertise of those trained to handle the helicopter.

Other choices suggest approaching at certain distances or times that may not consider safety protocols or the dynamic situation around a helicopter. It's crucial to follow the directives of qualified personnel to prevent accidents.