A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Position-Finding
From: John Blake
Date: 2017 Aug 6, 12:14 -0700
One volume of HO229 is for latitudes 0-45 degrees and the other is for latitudes 46-90. If we were on a training mission where we knew that we would not be going north of 45, we only carried one. For operational missions (airborne alert), we carried both.