Campaign - How to complete a mission

[Bersagliere81]

Hi there

I restarted several times the stock campaign for mig21, and I never managed to successfully finish the second mission.

 

I am following the instructions, which is get to the bullseye and shoot enemy aircrafts, without going too much into their airspace.

 

I get to a pooint where there are no more enemy aircrafts, and some -apparently- just stick over their airports with sam cover.

 

The only thing I can do is land back at Kutaisi and quit.

 

Does anyone have a hint on how to finish it?