At 19:06 06 June 2006, 303sam wrote:
Need some help getting clear on terms, please.
I'm planning a Diamond Distance flight of 326 miles.
The starting airfield
is at 300' msl. The finish will be at an airfield
elev 1150' msl. If I
take a tow to 2300' msl, notch the baro, climb to 5000'
msl and then cross
the start line am I penalized?

The safe and easy answer (I think) is to tow to no
higher than 4431' (finish
height + 3281), release behind the start line, notch
and cross the start
line, then climb up and start in earnest, but I'd like
to be clear on the
terms. Is the height difference measured from tow
release to finish or from
altitude when crossing the start line to finish?

Is an other safe answer to tow to 2300msl behind the
start line, climb to
whatever altitude I can, and declare the release to
be the starting point?


The start point can be whatever you want it to be:
http://www.fai.org/gliding/sc3.1.1
so if you release more than 500km from your finish,
you can say that your release point & altitude was
your start.

If you release 490km from your finish airfield, then
its the height at which you cross your predeclared
startline that matters.

On the other hand, your finish point can be whatever
you want so if you cross the startline at 5000', crossing
the finishline at 1800'+ won't incur any penalties.

So, option 1 will only be penalized if you release
500km from the finish & cross the finishline below
1719' msl. Option 2 is fine; you don't need to cross
a start line, your release point and altitude is where
you start. Option 3 is cheaper.

Edward