When aligning the IRS between 78 degrees 15 minutes North or South latitude:
A.A.Rotate the IRS switch from OFF to ALIGN
B.B.Alignment time will vary from 5 minutes to 17 minutes depending on airplane latitude
C.C.The alignment process begins when the ON DC light illuminates & the ALIGN light extinguishes
D.D.Airplane present position is not a required entry.
正确答案是B