  As the number of Unmanned Aerial Vehicles (UAVs) in the airspace grows,
ensuring that the aircraft do not collide becomes vital for further technology
development. In this work, we propose a new UAV Near Mid-Air collision (uNMAC)
safety volume taking into account i) Airframe size, ii) Localization precision,
iii) UAV speed/velocity, and iv) wireless technology capabilities. Based on
uNMAC, we demonstrate that inter-UAV separation distances can be reduced by
using UAV-to-UAV (U2U) communication while the safety levels remain unchanged.
Moreover, this work shows that next-generation Remote ID messages should
contain additional information (i.e., estimated localization error and, for
some applications, movement direction). As frequent broadcasting of Remote ID
can further reduce the separation distances, we identified 5G NR Sidelink,
Wi-Fi, and Bluetooth as suitable candidates for U2U communication.
