You get any indication on the Chan1 text buffer from the host?
I've killed aircraft climbing away from a field in a field gun (with tracers off). Mystifies them.
They ask where the hell I was!
Could be second similiar (tracers off) if they sneaked up below and behind you - best not to ever fly straight and level, or on auto climb unless no red blocks at all are showing in the sector. Roll the aircraft occasionally to check below and behind, as well as above.
I've been caught that way too many times, as I have caught others.