1013 -1003 = 10hPa x 30 = 300ft.   Altitude in ISA conditions = 15,700ft.

 

            FL160 ISA  =  +15oC – (2o x 16)      = -17oC

                                                            OAT     = -27oC

                                                            Dev.     = -10oC

            Difference between true altitude and pressure altitude is calculated as:

 

            4ft per1,000ft per oC ISA deviation = 4 x 15.7 x 10 = 628ft

 

            True altitude = 15,700 – 628 = 15,072.           Or use CRP5