NavList:

Chris,

On the paper almanac and your idea of including Pub. 211 instead of the
NAO Concise tables.

Ageton is attractive for the reason you give, one procedure for all
bodies and two pages of table, but it has a failure mode that matters
precisely for the user you describe, the one who does not practise the
method often. When K approaches 90 degrees, sin K = sin Dec / cos R
becomes ill-conditioned and the computed altitude can be wrong by tens
of arcminutes. Nothing in the form warns the navigator: the arithmetic
closes normally and the line of position is simply in the wrong place.
Ageton's own answer was to avoid those sights.

So if Pub. 211 goes in, the escape route has to go in with it, on the
same page as the form, not in a footnote. The identity
sin(90 - K) = tan R / tan LHA covers the region where the standard route
degrades, and reduces the worst case to a few arcminutes. Without it a
printed Ageton section is less safe than the NAO Concise, not more.

The NAO tables fail differently. They have no blind zone, but they have
sign and quadrant rules, and that is where people go wrong. A printed
section would be worth more with a compact decision table for those
rules than with another worked example.

Whichever you choose, a paper backup is only as good as its self-checks.
I would value a worked example with the intermediate quantities
tabulated, so the user can confirm he is reading the table correctly
before he trusts a fix.

Diego Melas