"Anyone know anything about them?"
Jeep
If you are on the PA spine and on AFPS 75, then for every year you serve beyond your IPP (subject to serving at least 5 years on the PA spine) you receive X pence per day increase to your pension. Clear as mud you see!
So an NCO pilot OR 6 who has done 10 years on the PA spine will get 10 * 0.999 pence per day in addition to their normal pension, extra a day on retirement.
You got that.
If you are on AFPS 05 then the PA supplements do not apply to you.