I'm trying to do the "Destroy 20 flying enemies before entering Sector 2" challenge, but I can't understand how it works...

I mainly use the Gunship, and even if I destroy a lot of ships and drones, the counter is always 1 or 2... at some point I also waited for the Okkar to arrive, and killed most of them before the mothership arrived, and I had the counter to 3...
Seems to me that it counts only the ones destroyed by missiles...

So, how it works ?

Is it possible that the units killed by the turret do not count ???

I did an internet search before writing here, but found nothing about this issue... but looking better, I now I see some references in the Wiki, it's not specified in this challenge but in some others yes.

I'll do some tests and report.

Just to report that after some tests I found out that all primary/secondary weapons works (but only if they hit directly)... if you launch mines, them don't count.

Kills by drones and friendly units are not counted.