Mandargb asked:"Please correct me if I am wrong
My understanding is 1nm = 1minute of latitude at equator. "
Mandargb, you are not wrong in stating that. But if you are implying that it's only true at the equator, then that's not entirely true. 1nm is equal to 1 minute of latitude everywhere on earth since latitude lines are all parallel to each other. For longitudes 1minute = 1 nm multiplied with the cosine of latitude since longitudinal lines gets closer (smaller) and meet at the two poles. In this case, 1 min = 1 nautical mile for longitude only at the equator. Anywhere else it is less by cosine of the latitude.