AIP = Advanced Incremental Progression (or words to that effect)
Great management speak really
Allows you to jump a couple of rungs up the pay ladder as a pay back for gaining some useful qualifications, e.g. get qual x and be paid as a Level 6 Sgt instead of a Level 5 Sgt - so worth up to about £1000 a year per level (depending on rank/seniority etc).
Now if they let me loose on AIP taken together with PA Spine
D4R