If a plane and RPAS are close then an autopilots should negotiate automatically and change altitudes respectively. Certainly a manned aircraft has got a priority. There is enough space in 3D world, it is not like at the 2D road intersection. Ans it is doable, as only five figures are to be exchanged periodically: altitude, latitude, longitude, heading, speed, - no broadband is needed to transmit them.
If there is a massive fire people will fly drones anyway to see if they should evacuate their homes or stay. It is possible to build a DYI drone from improvised materials.