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

On Sep 8, 8:38 am, wrote:
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- Hide quoted text -

- Show quoted text -

It's a tough situation. In 20 years of racing I've never been in a
situation where the safety finish was in effect. So, many (most?) of
us probably are only vaguely aware that the option exists and have
only a loose grasp on the rule.

I think the comments so far make sense. Is there anything that we
could do to reduce/eliminate the mental gymnastics required to figure
out the floor of the cone? It's all very simple sitting here at the
dining room table with coffee in hand, but under the gun with a Cu
Nimb staring you in the face...

I'm thinking maybe in terms of the inverted layer cake approach which
typifies Class B and C airspace. The likely options are 5, 10, and
15 mile radius cylinders. The minumum altitude at each would be set
at the appropriate glideslope beforehand.

Since there's no competitive advantage to going any further than the
outer radius of the cylinder, having a cone rather than a layer cake
doesn't really make practical sense to me.

P3

It's a tough situation. In 20 years of racing I've never been in a
situation where the safety finish was in effect. So, many (most?) of
us probably are only vaguely aware that the option exists and have
only a loose grasp on the rule.

Wow! I've personally experienced at least three different 'safety
fiinish' situations in eastern regionals and nationals. Come to think
of it, two of these were at CCSC - maybe my home soaring area isn't
quite as benign as I think! ;-).

Regarding the altitudes, it really doesn't make too much difference.
When you are faced with the situation, you get as much altitude as you
can, and then try and nick the cylinder without scaring yourself too
badly. Personally I like the cone idea, as it is easy to remember '5
miles per thousand feet'. With the current 5sm radius cylinder, If
you are more than 1000' above the home field (and this is usually easy
to confirm with the flight computer), you are good to go. At 10
miles, you need twice that. In between, you have to interpolate, but
its not too bad. Also, if the rule were very simple (like 200ft/
mile), then it might be possible to program it into soaring software
so you could simply enable a checkbox to change the glide calculations
from whatever you have as a polar to show '200ft per mile'.

Just my $0.02

Frank(TA)

On Sep 8, 11:08 am, Frank wrote:

Regarding the altitudes, it really doesn't make too much difference.
In between, you have to interpolate, but its not too bad. Also, if
the rule were very simple (like 200ft/
mile), then it might be possible to program it into soaring software
so you could simply enable a checkbox to change the glide calculations
from whatever you have as a polar to show '200ft per mile'.

Just my $0.02

Frank(TA)

But that's the rub. Again "not too bad" is a relative term. With
high workload and stressful conditions, I've seen plenty of people
lose the ability to do even simple math. My thought is that just
having one number to worry about (e.g. 10 miles and 1550 on the
altimeter) makes it much easier. I can't see any scenario where it
would be worthwhile to go to, say, 7 miles and then try to climb up,
especially when the conditions warrant a safety finish at 10 miles.
No?

As far as having "soaring software" to accomodate this stuff, it's
becoming a non-trivial exercise to support all of the various rules
for different countries. All the more reason to make it a KISS
rule.

P3

But that's the rub. Again "not too bad" is a relative term. With
high workload and stressful conditions, I've seen plenty of people
lose the ability to do even simple math. My thought is that just
having one number to worry about (e.g. 10 miles and 1550 on the
altimeter) makes it much easier. I can't see any scenario where it
would be worthwhile to go to, say, 7 miles and then try to climb up,
especially when the conditions warrant a safety finish at 10 miles.
No?

I'm just guessing here, but isn't the point behind the downward slope
to the cylinder to keep pilots who are below the floor from having to
glide all the way to the airport to get a finish? With a flat floor
you end up having to find a thermal (possibly under an overcast) to
reach the floor or do a normal finish at ground zero. So say the
safety cylinder is 10 miles and 2000' and you are at 1900' with no
possibility of climbing. What would you do? The temptation would be to
try to get home.

I'm also guessing that the reason the safety cylinder wasn't
originally conceived with the possibility for a larger radius is to
keep from catching too many pilots between the safety cylinder and the
finish line when it is invoked by the CD. I can imagine all kinds of
protests in that scenario.

9B