NavList:

Lars Thanks

That looks great.  I’ll print a copy off and read it tomorrow morning when my brain is clearer.  I sat an astro exam which was nearly all haversines in 1973.  I was taught and examined by a USAF C141 Navigator called Chuck Garcia.  On the first day he said the exam would be in Spanish, but that was his little joke.  To keep the pressure on, the exam was designed so no one was expected to finish.  Determined to do so, I designed and drilled myself in a robotic system; finished; and got 100%.  The trouble with my system was that 30 minutes after the exam finished, I couldn’t remember a thing about haversines, and I still can’t 47 years later. DaveP