Mike the Strike wrote:
Fred:

Sorry, but I still disagree.

The time of sunset is the point at which the limb of the sun disappears
to an observer. This is an exact legal definition.

I don't think you'd get far in a court of law if a dozen eyewitnesees
said the sun was still visible but you said your mathematical equation
predicted that it had set!

Probably not, even if the law specified that the legal defintion of
sunset was that estimated by the exact legal model. But mens
rea isn' t really at issue here, is it?


For convenience, we use a mathematical model that uses a constant term
to correct for atmospheric refraction and you can look up those times
in published tables. However, the correction is approximate and
subject to error.

I merely suggested that since the actual time of sunset was not known,
we should allow folks some slack if they land close to sunset to allow
for this error.

My suggestion for dealing with the ambiguity of the actual time of
sunset is to not use the actual time of sunset. Use the putative
time of sunset, as calculated by a standard formula for the
published lattitude and longitude of the airfield in question instead.
That eliminates the ambiguity. All the pilot needs is to plan
ahead by looking up the putative time of sunset for the various
airfields and an decent clock. If he has a GPS receiver, he
has an extremely accurate clock.

Do you suppose the FAA has addressed this issue?

Allowing them some slack is fine, but does not address the problem.
When does the grace period begin and when does it end?
I'm not addressing the issue of what should be done about
those who land after the deadline, whatever it would be. Only
the practical issue of what to base that deadline on. If you
base it on the 'actual' time of sunset, no one knows what
that deadline is, not in advance, nor even after the fact.

As for what is fair and what is not, IMHO the more objective,
precise, and predicable a rule is, the more fair it is regardless
of how arbitrary it is.

--

FF