**Q:** What does "on fire" mean?<br/>
**A:** When your plane is damaged to a certain extent it starts to smoke, this is what's classed as "on fire".

**Q:** Is the counter reset each round?<br/>
**A:** No the counter is not reset.

What this objective fails to mention is that you have to kill your enemies by **ramming** into them. This is not at all clear and so leads to confusion.