Staying clear of the area directly above and below other jumpers during freefall is crucial primarily due to the possibility of AAD (Automatic Activation Device) activation. The AAD is designed to deploy your parachute automatically if it detects that you've reached a certain altitude and you're still in freefall, which typically occurs when a jumper is unable to deploy their main parachute due to either incapacitation or delay.
If jumpers are in close proximity, there is an increased risk that the AAD could accidentally deploy at an altitude where another skydiver is still present. This can lead to dangerous situations, such as a potential collision during a time when parachutes are deploying. Maintaining a safe distance minimizes the risk of injuries from tangling with another jumper's parachute, which can have severe consequences for both parties involved.
Focusing on the area overhead and beneath also helps in maintaining spatial awareness, allowing jumpers to avoid coming into contact with one another, thus ensuring safety and preventing accidents during the parachute deployment phase.