At 10:18 01 June 2004, Marc Ramsey wrote: (snip)
How much security is enough?

It is perhaps here where there is the greatest problem.
It seems that most people view the 'security' measures
applied to barographs and loggers as a measure to prevent
cheating. They do not and never will. All security
does is buy time, it makes cheating more difficult
so the 'man on the Clapham Omnibus' (for those across
the pond, the ordinary man in the street) cannot easily
fake a trace. While reading this thread I am somewhat
at a loss as to why somene would want to load in a
flight to a GPS using a simulator, much easier to doctor
the ensuing computer file. Any security measure involving
a computer can be defeated, it's the time it takes
that makes the difference.
For that reason I always, if I am the OO download to
my own computer, never to anyone elses and I keep a
copy of the file forever.
A GPS sealed in a box is as secure, if not more so
than a smokey barograph. It is many more times secure
as a computer file produced by a 'secure' logger, the
security algorithums of which are historically interesting,
almost. The information contained in the GPS memory
is raw source data, that produced by the logger is
not. Replacing a proper seal as used on smokey barographs,
if all the rules are followed, is infinitely more difficult
than decoding and faking a computer file.

I seem to recall someone earlier inthis thread saying
that geometric altitude was more accurate and easily
corrected than barometric, which as we all know is
wildly inaccurate dependent on temperature which the
barograph does not record.