Safety finish rule & circle radius

On Sep 8, 1:07 am, CLewis95 wrote:
Frank,

My circumstances were identical to yours that day.

Keeping the 5sm radius as a minimum, and specifying a maximum radius
the CD can call, is well worth considering. The only issue I can see
is the clear communicating of the "CD chosen" radius along with the
announcement that the Safety Finish was in effect. I remember how
hectic the radio traffic was during that time. This could be helped a
little by allowing only 5 or 10 (and/or 15?) mile radii to be called
by CD. Pilots could anticipate one of these values...as opposed to
listening for and clearly understanding for example a "7 mile safety
finish is in effect" from the CD.

Great issue for more discussion.

Curt - 95

On Sep 7, 1:57 pm, Frank wrote:



As a result of a somewhat harrowing experience at the recent Sports
Class Nationals at CCSC, I have been thinking about possible
modifications to the current saftety finish rule. The recent post
regarding the upcoming rules committee vacancy prompted me to post my
thinking. I would be particularly interested in what the candidates
for the vacancy have to say about the original rule and my proposed
modification.

Background:

On one of the days at the 2007 Sports Class Nationals, a very large T-
storm decided to visit the home field just as the fleet was trying to
return. The CD announced that a safety finish was in effect. The
safety finish 'cylinder' is actually a 5-statute-mile radius vertical
cylinder with a conical base. The tip of the conical 'floor' is
located at the home airport and it has a slope equal to (I think)
200ft/mile.

About half the fleet (including myself) made it home, and the rest
landed at other airports or in surrounding fields. However, the storm
was so large that it was very difficult, if not impossible, to achieve
a valid safety finish without seriously compromising safety.

Looking back on that day, it appears the safety finish option, as
applied in this case, had the effect of degrading, rather than
enhancing, safety. Because the storm was much larger than 10 miles
across, pilots were forced to continue into the storm area if they
wanted to take advantage of the safety finish rule.

At about 10 miles out, I had way more than enough altitude to get
home. Lacking an accurate assessment of the seriousness of the
situation, I chose to continue toward the home field, thinking I would
nick the 5 mile ring, then turn back and land at an alternate
airport. As it turned out, by the time I got to the 5 mile point, I
felt it was safer (i.e. not quite as life-threatening) to continue
ahead than it was to turn back. This was a dubious choice at best,
and the fact that I managed to survive the experience has a lot more
to do with luck and (almost) terminal stupidity than anything else.
Several other pilots related similar stories.

After thinking about this a while, I wondered why the radius of the
'cylinder' has to be a fixed number. In our case, if the radius had
been set to 10 or 15 miles, everyone could have easily landed at
surrounding airports after penetrating the cylinder above the cone
floor. At 10 miles out I was more than twice the height of the cone
'floor', and I know others were at the same place and altitude.

So, my proposal is to modify the safety finish rule to let the CD
decide the radius to be used for the cylinder whenever it is
activated, with maybe a 5 mile minimum. I really don't see the need
to establish a maximum radius, as I think most modern gliders have a
glide ratio greater than 200 feet/mile. If you are above the cone
floor at X miles out, then more than likely you will stay above the
floor until you descend to land (if not at the home field, then
somewhere else). If you are below the floor, then continuing inward
makes sense until you get near the bad weather, at which point it
should be very obvious you aren't going to get a valid safety finish
no matter what you do.

Any thoughts on this?

Frank(TA)- Hide quoted text -

- Show quoted text -

Frank, I agree with Curt Lewis that perhaps a 5 OR 10 mile radius
would be less confusing. I would also emphasize that it would be a
good idea for the CD to have a good discussion of the rule on the
first day that T-storms are possible. I can attest to the fact that 5
miles was not enough on the day in question. In my case, 10 miles
would have been plenty but you have to be tuned in to the fact that a
safety finish may be called, have a good understanding of the rule and
then the CD has to call it at the first signs of approaching danger.
That in itself is very difficult because these cells have a way of
developing so fast.

JIm Price - 77