Lesson 10 Determining a FIX by Plotting LOPs

LESSON 1
LESSON 2
LESSON 3
LESSON 4
LESSON 5

LESSON 7
LESSON 8
LESSON 9


OK, we're most of the way through the puzzle.  We know how to determine the GHA and declination of a body at a given moment in time.  We know how to use that GHA and declination and an assumed  position to determine the computed altitude and azimuth of the body from the assumed position at the given moment in time.

We now know how to correct a sextant altitude taken of the same body for instrument error, index error, dip of the horizon(due to height of eye), and several astronomical and atmosphere errors to arrive at an observed altitude of the body.

We now know how to compare the computed altitude and the observed altitude to determine an intercept length and a direction toward or away from the GP of the body from the assumed position along the azimuth determined by computation.

We're now going to plot more than one LOP and use the intersection of those LOPs to create a FIX, or fixed position.  A fixed position, also called a most probable position (MPP) is one which is considered sufficiently certain by a navigator to break off an old dead reckoning plot and start a new dead reckoning plot from the FIX.

Good luck with your plot.

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