Which factor relates to in-flight stability of a sling load?

Weight is a crucial factor concerning the in-flight stability of a sling load. When considering sling load operations, ensuring that the load is appropriately balanced and within the helicopter's weight limits is essential for maintaining stability during flight. A load that is too heavy can affect the helicopter's performance and maneuverability. Additionally, if the weight is unevenly distributed, it can lead to erratic movement during transport, increasing the risk of oscillation or swinging, which can jeopardize both the load and the aircraft's safety.

While altitude, temperature, and humidity can influence helicopter performance and operational parameters, they do not directly affect the stability of the sling load in the same way that weight does. For instance, altitude may impact engine performance due to thinner air, and temperature can affect lift capabilities, but these factors are more about the helicopter's general operational state rather than the stability of the specific load being carried. Weight, however, is a defining characteristic of how well a sling load will behave in the air.