NavList:

   

Reply

Renee Mattie wrote:

> I'm having problems with "100 Problems"
> [...] after working the first 6 problems, I am finding myself 5-10 miles
> away from the
> author most of the time.

Renee,

I reduced problem 1-6 with a computer program and obtained a fix at N 40
09.6 W 046 5.2 where Gray gets N 40 09 W 46 04.

A difference of 1 mile in each coordinate is too high to blame it on
different sight reduction methods. More likely, the difference comes from a
bad estimate or an arbitrary choice of the MPP (most probable position)
within the cocked hat. Since the cocked hat consists of 6 lines it is
difficult to guess the MPP from the geometry of the LOPs.

However, 5 miles difference indicates an error. I notice that Gray
specifies index correction, not index error. Did you get this right? A
confusion of this kind can easily throw you off by 5 miles.

Post your results for problem 1-6 (DR, intercepts and azimuths of
individual LOPs), then we can discuss them. Those who think that particular
sight reduction methods can lead to a result 5 miles off are invited to
demonstrate them to us so that we can avoid these methods in the future.

Herbert Prinz

   

Reply