What formation provides the least amount of security during landing?

The formation that provides the least amount of security during landing is the line formation. In this setup, aircraft align themselves in a straight line, which limits their ability to cover one another effectively. This lack of coverage makes the formation more vulnerable to potential threats during the landing phase.

In contrast, other formations such as the diamond, box, and inverted Y offer better mutual support among the aircraft. The diamond formation allows for a wide field of view and enables aircraft to engage threats from various angles. The box formation provides overlapping fields of fire and can protect vulnerable areas more effectively. The inverted Y formation also facilitates better coverage and security compared to the line formation. Thus, due to the straight alignment of the line formation, it inherently reduces the overall defensive posture of the aircraft involved during landings, leading to increased exposure to threats.