Which flag indicates that personnel are working aloft?

The Kilo Flag is used to indicate that personnel are working aloft, which refers to operations being conducted at heights above the ship's main deck, such as on masts or antennas. This flag serves as a safety warning to others in the vicinity, signaling that there are individuals engaged in potentially hazardous activities above the ship's deck level. The visibility of the Kilo Flag is crucial for alerting crew members and other vessels nearby, helping to ensure that proper safety protocols are followed and reducing the risk of accidents during these operations. The other flags listed do not serve this specific purpose; thus, the Kilo Flag is the correct indicator for when personnel are working aloft.