As it seems, the Air Force Engineering University is using retired J-11 fighters as training assets. The original serial numbers of the J-11 have been removed but these images at least show three with the numbers 5015, 5016 & 5017. One of them has the construction number "0004".
That's indeed interesting for several reasons:
1. They appear to be Batch 00 aka prototypes & LRIP J-11 and not J-11B even if they have likely a painted "full-size" radome without the typical cut-out
2. They appear to be the first fighter-Flankers spotting low visibility markings.
3. Indeed, the numbering system 5x1x is not assigned to any operational training unit.
View attachment 167138View attachment 167139