# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: We were off-course 97% of the time
Date: 2016 Jun 12, 02:08 -0400

3% of the time on course, based on what tolerance?

Suppose the tolerance was a nanometer.  Then the trajectory would be wrong 99.99999% of the time.  It's only right at the very instant that the actual course and theoretical course cross each other.

Suppose the tolerance was 1,500,000 miles (more than the distance to the moon).  Now the vehicle is following the trajectory 100% of the time.  It's perfect!!

I agree with Frank.  The percentage cited is absolutely an irrelevant figure of merit, without a thorough understanding of the parameters.

Consider the statement to be a great way to amaze the crowd!!

On Jun 11, 2016 11:20 PM, "Frank Reed" <NoReply_FrankReed@fer3.com> wrote:

The numerical value is meaningless. It makes for a better story. And I find that 98% of stories told by all salts are above average anyway...

Setting aside the numerical value, the navigational concept highlighted by the tale is certainly true: Mission Control was required to guide the Apollo missions to the Moon and back. Before anything else, that was the Mission Control's job. Ground observations regularly updated the orbits, also known as state vectors, and provided the details for the rocket burns which would adjust the orbits to bring them in line with mission goals.

Frank Reed

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