There is something much more significant under the cover that the cooperation has a very great depth although both countries avoid naming themselves as allies. Not only Pakistani pilots can access Chinese aircraft like J-11BS (Please note J-11B series have all China made avionics instead of Russian made stuff), they also have access to PLAAF's real-time data link at least through JF-17's avionics. Otherwise they wouldn't be able to work with PLAAF's SAM and ground radar forces to exercise repelling enemy air strikes.