I built one too, but it's not that hard to reverse engineer.
Healthcare , Dental, FSA's, HSA, Vision and 401K are all tax exempt deductions. NT PD (Non Taxable Per Diem) is also not subject to tax.
Voluntary Life (Vol Life), Spouse Life (SP Life) and Long Term Disability (LTD) are non tax deductible deductions.
In a very simple case take your pay rate, multiply it by hours on the check. Add any Taxable Per Diem and Special Items (Parking Allowance for example). That will be Taxable gross pay. Excluding NT Per Diem multiply that by 1.9%; those are your ALPA dues.
Medicare is 1.45% of taxable (plus 401K which IS subject to Medicare tax).
Social Security is 6.2% of taxable ( again plus 401K which is subject to SS tax). If it applies to you, SS tax stops being collected at $128,400, so any earnings in 2018 in excess of that aren't subject to SS tax.
Alright, looking back that wasn't a very simple explanation. Hopefully HighFlight explained it better, or sent you a spreadsheet.