When astronomical sights have been reduced by means of tables calculated for a fixed equinox, it is necessary to make a correction for the precession that has occurred since the date for which the tables were calculated. In the Astronomical Navigation Tables this correction is applied to each intercept separately. It is, however, possible to apply the correction once only to the fix obtained. This would probably be simpler, particularly with such tables as the Experimental Air Navigation Tables and H.O.249.