# a-Lat

Take your DR-Lat and round it up or down to whole degree.

# a-Lon

Choose

**a-Lon° = DR-Lon°**and**a-Lon' = GHA'**- Look at the difference and call it Delta
- You're done if delta is less than or equal
**30'**. The AP is**a-Lon° a-Lon'**=**DR-Lon° GHA'** - If Delta is greater than
**30'**, then we need to change**a-Lon°**by**1°**up or down according to step 5 or 6 **Western Longitude:**If**GHA'**is greater than**30'**then decrease**a-Lon°**by**1°**and increase it if it's less than**30'****Eastern Longitude:**If**GHA'**is greater than**30'**then increase**a-Lon°**by**1°**and decrease it if it's less than**30'**.

## Glossary

a-Lat = Assumed Latitude, a-Log = Assumed Longitude, DR = Dead Reckoning, GHA = Greenwich Hour Angle