OROP notification dated 07.11.2015 stipulate that

1. To begin with, pension of the past pensioners would be re-fixed on the basis of pension of retirees of calendar year 2013 and the benefit will be effective with effect from 1.7.2014.
2.Pension will be re-fixed for all pensioners on the basis of the average of minimum and maximum pension of personnel retiring in 2013 in the same rank and with the same length of service.
3.Pension for those drawing above the average shall be protected.
So the 'minimum' and 'maximum' pension sanctioned in the calender year 2013 to each rank with same length of service are critical to calculate the OROP.

HOW TO CALCULATE THE MINIMUM & MAXIMUM PENSION?

I will make an attempt to calculate them on real time basis by an illustration of eight (A - H) X Group Havildar/Petty Officer/Sergeant with 15 years of service whose service particulars ar as given below:-
1. Pay & Pension calculation of "A":-
15.12.98. LAC (4025-60-4925) 4025
01.12.03. 4025+(60×5) =4325
15.12.03 Promoted as CPL (4150-70-5200)
15.12.03. Pay fixed as CPL - 4430
01.01.06 - 4430(70×2) =4570
01.01.06 - 6th CPC- 14310
01.01.06 - Promoted as Sgt-15080
01.07.06 -15480
01.07.07 -15890
01.07.08 -16310
01.07.09 -16740
01.07.10 -17190
01.07.11 -17650
01.07.12 -18120
01.07.13 -18610
31.12.13 - DISCHARGE
PENSION - 18610/2 = 9305/-
2.Pay & Pension calculation of "B":-
15.12.98. LAC (4025-60-4925) 4025
01.12.03. 4025+(60×5) =4325
15.12.03 Promoted as CPL (4150-70-5200)
15.12.03 -Pay fixed as CPL - 4430
01.01.06 - 4430 + (70×2) = 4570
01.01.06 - 6th CPC- 14310
01.07.06 -14680
01.07.07 -15060
01.12.07 -Promoted as Sgt -15860
01.07.08 -16280
01.07.09 -16710
01.07.10 -17160
01.07.11 -17620
01.07.12 -18090
01.07.13 -18580
31.12.13 - DISCHARGE
PENSION - 18580/2 = 9290/-
3.Pay & Pension calculation of "C":-
15.12.98. LAC (4025-60-4925) 4025
01.12.03. 4025+(60×5) =4325
15.12.03 Promoted as CPL (4150-70-5200)
15.12.03 -Pay fixed as CPL - 4430
01.01.06 - 4430 + (70×2) = 4570
01.01.06 - 6th CPC- 14310
01.07.06 -14680
01.07.07 -15060
01.07.08 -15460
01.12.08 - Promoted as Sgt - 16270
01.07.09 -16700
01.07.10 -17150
01.07.11 -17610
01.07.12 -18080
01.07.13 -18570
31.12.13 - DISCHARGE
PENSION - 18570/2 = 9285/-
4.Pay & Pension calculation of "D":-
15.07.98. LAC (4025-60-4925) 4025
01.07.03. 4025+(60×5) =4325
15.07.03 Promoted as CPL (4150-70-5200)
15.07.03. Pay fixed as CPL - 4430
01.01.06 - 4430(70×2) =4570
01.01.06 - 6th CPC- 14310
01.07.06 - 14680
01.07.07 - 15060
01.07.08 - 15460
01.07.09 - 15870
01.08.09 - Promotion as Sgt- 16690
01.07.10 - 17130
01.07.11 - 17590
01.07.12 - 18060
01.07.13 - 18550
31.07.13 - DISCHARGE
PENSION -18550/2 = 9275/-
5.Pay & Pension calculation of "E":-
15.07.98. LAC (4025-60-4925) 4025
01.07.03. 4025+(60×5) =4325
15.07.03 Promoted as CPL (4150-70-5200)
15.07.03. Pay fixed as CPL - 4430
01.01.06 - 4430(70×2) =4570
01.01.06 - 6th CPC- 14310
01.07.06 - 14680
01.07.07 - 15060
01.07.08 - 15460
01.07.09 - 15870
01.07.10 - 16290
01.12.10 - Promoted as Sgt - 17120
01.07.11 - 17580
01.07.12 - 18050
01.07.13 - 18540
31.07.13 - DISCHARGE
PENSION - 18540/2 = 9270/-
6.Pay & Pension calculation of "F":-
15.07.98. LAC (4025-60-4925) 4025
01.07.03. 4025+(60×5) =4325
15.07.03 Promoted as CPL (4150-70-5200)
15.07.03. Pay fixed as CPL - 4430
01.01.06 - 4430(70×2) =4570
01.01.06 - 6th CPC- 14310
01.07.06 - 14680
01.07.07 - 15060
01.07.08 - 15460
01.07.09 - 15870
01.07.10 - 16290
01.07.11 - 16720
01.12.11 - Promoted as Sgt -17570
01.07.12 - 18040
01.07.13 - 18530
31.07.13 - DISCHARGE
PENSION - 18530/2 = 9265/-
7.Pay & Pension calculation of "G":-
15.07.98. LAC (4025-60-4925) 4025
01.07.03. 4025+(60×5) =4325
15.07.03 Promoted as CPL (4150-70-5200)
15.07.03. Pay fixed as CPL - 4430
01.01.06 - 4430(70×2) =4570
01.01.06 - 6th CPC- 14310
01.07.06 - 14680
01.07.07 - 15060
01.07.08 - 15460
01.07.09 - 15870
01.07.10 - 16290
01.07.11 - 16720
01.07.12 - 17170
01.12.12 - Promoted as Sgt - 18030
01.07.13 - 18510
31.07.13 - DISCHARGE
PENSION - 18510/2 = 9255/-
8.Pay & Pension calculation of "H":-
15.01.98. LAC (4025-60-4925) 4025
01.01.03. 4025+(60×5) =4325
15.01.03 Promoted as CPL (4150-70-5200)
15.01.03. Pay fixed as CPL - 4430
01.01.06 - 4430(70×3) =4640
01.01.06 - 6th CPC- 14440
01.07.06 - 14820
01.07.07 - 15210
01.07.08 - 15610
01.07.09 - 16020
01.07.10 - 16440
01.07.11 - 16880
01.03.12 - promotion as Sgt - 17730
01.07.12 - 18210
31.01.13 - DISCHARGE
PENSION -18210/2= 9105/-
Therefore the average between 'minimum' and 'maximum'could be the following :-

(9305+9290+9285+9275+9270+9265+9255+9105) = 74050/8 = 9256/-
The classification pay if added could increase the average marginally. We can therefore safely conclude the OROP of a Group X
Hav/PO/Sgt with 15 years of service will be approximately 9250/- plus/minus 50/-.
A difference of 9250 - 6374 =
2876/- in Basic Pension.
Arrears incl. DR receivable for 18 months from 01.07.14 to 31.12.15
2876 × 38.34 = 110266/-.
Arrears per instalment -110266/4 = 27567/-
Pension from 01.01.2016 with 119% DR will be - 20258/-
CAUTION: Errors and omissions expected in the above calculations.
This is just an attempt to calculate OROP.
The real time data could be different.
We need to wait for the official charts to be notified by CGDA/PCDA.
Sgt MPKaran

Source: http://ex-airman.blogspot.in/