Which of the following is NOT a landing formation?

The formation referred to as "Circle" is not typically recognized as a landing formation in the context of helicopter operations. Landing formations are specific arrangements that helicopters use to safely land and operate in close proximity to one another, allowing for coordinated movement and management of airspace.

The Diamond, Vee, and Echelon Right formations are established landing formations, each designed for specific tactical advantages and safety considerations. The Diamond formation allows for a tight, controlled grouping of helicopters, facilitating an organized landing process. The Vee formation is effective for maintaining visibility among aircraft while also optimizing spacing during landing. Echelon Right allows for staggered positioning, which helps in reducing risk during landing, especially in combat scenarios.

In contrast, a Circle formation does not provide the same level of structure or safety as these other formations when it comes to landing operations; instead, it may imply a more informal or less organized grouping that is not suitable for the precise coordination required during landings. This distinction clarifies why "Circle" is the correct answer in identifying which option is not a recognized landing formation.