Online Ground School (Private Pilot)

Lesson 16.3 : Latitude and Longitude

Latitude and Longitude

     Reference: ACS PA., PHAK Sec 16

Latitude lines are the imaginary lines that circle east and west, parallel to the equator.  These lines are used to measure north (N) and south (S) of the equator.

longitude lines are the lines that circle north and south.  These lines are used to measure east (E) and west (W).  The "Prime Meridian" is the line used for the      line.  This line runs through Greenwich, England.

Longitude lines are also called meridians, they help designate times zones.  Each time zone is a difference of one hour.  There are four time zones in the continental United States, they are:

  • East 

  • Central

  • Mountain

  • Pacific

In aviation, the time used is expressed in a 24 hour clock also known as Military time.  So, 9:00 am is written or said as 0900.  1:00 pm would be 1300, and 10:00 pm is 2200. 


After midnight (2400 hours), the time for 12:15 am would be 0015. 12:30 is 0030.  


Since you as pilot may cross multiple time zones a standard time system is used in aviation, its called UTC or Zulu time.


More on UTC and Zulu time in the next lesson.


Lines of Latitude
Lines of Longitude


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