I'll deal with your pain Lusche...
Anyways.. here how's it works..
Step 1. Your plane touch the other guy's plane.
Step 2. On your computer, it shows that you touched his aircraft.
Step 3. On his computer, it shows that you didn't.
Step 4. The system determines that you touched the other guy's plane, and give you the damage.
Step 5. You go down, all he gets is a message saying you rammed him.
This is caused by lag/latency/bandwidth/connections problems.
EDIT: I couldn't find the picture that showed this happening.. if anyone else finds it, great.