Which of the following icing intensities require deicing equipment to prevent significant accumulation during flight?

The correct answer is that moderate icing intensity requires the use of deicing equipment to prevent significant accumulation during flight.

In aviation, icing conditions are categorized based on intensity levels: trace, light, moderate, and severe. Moderate icing is significant enough that it can lead to hazardous situations if not addressed promptly with deicing measures. In this category, the ice accumulation can adversely affect aircraft performance, making it crucial for pilots to activate deicing systems before or during flight to manage the ice buildup.

While severe icing is almost universally acknowledged to need immediate deicing, light and trace icing conditions typically do not require activation of deicing equipment, as they tend to be manageable without immediate intervention. Understanding the specific requirements for moderate icing is essential for ensuring flight safety and maintaining control of the aircraft in potentially hazardous weather conditions.