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Pending reduction in US MAT turnpoint radius



 
 
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  #1  
Old February 4th 19, 10:08 PM posted to rec.aviation.soaring
John Godfrey (QT)[_2_]
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Default Pending reduction in US MAT turnpoint radius

The 2019 proposed US competition rules reduce the turnpoint radius for the Assigned Task to 0.5 sm from 1 sm (a reduction of the turnpoint area of 75%).

This change also applies to the MAT task turnpoints.

Reducing the MAT radius, where gliders may be approaching a turnpoint from many different points of the compass, doesn't seem like such a good idea to me from a safety perspective.

QT
  #2  
Old February 4th 19, 11:19 PM posted to rec.aviation.soaring
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Default Pending reduction in US MAT turnpoint radius

FWIW, it also "requires" changing the software for at least some flight computers. The radius may be configurable for some apps but for what I use, the default is 1 mile for ASTs. It's fairly straightforward to work around this by simply watching "distance to go" as it counts down for each TP but it's not right and could have a minor impact on ETA calculations. I wasn't going to be critical but in my narrow scope of thinking, triggering an application change for a very small Rules change with marginal benefit is the kind of thing I expect from the government. Good thing ASTs are almost dead in this country. Hahaha. Sorry for not seeing the big picture.

Chip Bearden

  #3  
Old February 5th 19, 12:50 AM posted to rec.aviation.soaring
Tango Eight
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Default Pending reduction in US MAT turnpoint radius

On Monday, February 4, 2019 at 4:08:41 PM UTC-5, John Godfrey (QT) wrote:
The 2019 proposed US competition rules reduce the turnpoint radius for the Assigned Task to 0.5 sm from 1 sm (a reduction of the turnpoint area of 75%).

This change also applies to the MAT task turnpoints.

Reducing the MAT radius, where gliders may be approaching a turnpoint from many different points of the compass, doesn't seem like such a good idea to me from a safety perspective.

QT


Wellllll, some of us can remember when it was 0.25 SM radius, and we lived through that....

I'm guessing the motivation was to make US turnpoints more FAI like?

The important difference between USA and FAI AT turns isn't the radius, it's how distance is calculated.

The FAI turn is "tag and go" (just like that 0.25 SM radius turn was, circa 1999). Some famous RC guys maintain this is dangerous because it drives all the gliders towards a single point (because there is no benefit to penetrating the turn). Others maintain that this is in fact safer (on an AT) because it makes pilots more predictable. Lately, I incline towards the latter view. The US style turns (which are simply small area turns, distance scored to best fix) sometimes tempt guys to get cute.

I agree that shrinking the MAT turn size isn't a good idea.

The main change that could benefit safety on MATs (if we still have to have them at all) is in task calling guidance. The practice of assigning not quite enough turns to fill out minimum time and having the last assigned turn close to home base yields a very weird and sometimes unpleasant free for all and it should be strongly discouraged.

best,
Evan Ludeman / T8
  #4  
Old February 5th 19, 04:34 PM posted to rec.aviation.soaring
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Default Pending reduction in US MAT turnpoint radius

I remember a fatal midair over Bridgeport, Ca. When we had 1/4 mile radius! Both pilots were looking at the photo target when hitee slid directly under the hitter, who made a hard left turn to get his photo of the turnpoint. His left wing tip hit the cockpit of the other glider, which spiraled in. Hitter was able to land OK. Won’t the new rule require “eyes in cockpit”, as we watch the DME count down to .5?
I also like to use the1 mile radius to “adjust” my time on the final TP. You can burn 4 productive minutes by going a mile beyond the TP, then reverse and head for the barn. Is there a good reason to change the radius? Scoring programs will need to be changed, also!
JJ
  #5  
Old February 5th 19, 05:30 PM posted to rec.aviation.soaring
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Default Pending reduction in US MAT turnpoint radius

On Tuesday, February 5, 2019 at 10:34:14 AM UTC-5, wrote:
I remember a fatal midair over Bridgeport, Ca. When we had 1/4 mile radius! Both pilots were looking at the photo target when hitee slid directly under the hitter, who made a hard left turn to get his photo of the turnpoint.. His left wing tip hit the cockpit of the other glider, which spiraled in. Hitter was able to land OK. Won’t the new rule require “eyes in cockpit”, as we watch the DME count down to .5?
I also like to use the1 mile radius to “adjust” my time on the final TP. You can burn 4 productive minutes by going a mile beyond the TP, then reverse and head for the barn. Is there a good reason to change the radius? Scoring programs will need to be changed, also!
JJ


The reason is to more closely align with IGC rules without going to metric.
"Good" reason depends on individual point of view.
UH
  #6  
Old February 5th 19, 06:54 PM posted to rec.aviation.soaring
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Default Pending reduction in US MAT turnpoint radius

I used to criticize the Rules Committee for making myriad annual changes that required WinScore to be modified, introducing the potential (read: certainty) for bugs. It was like the Fed or Congress tinkering with interest rates or the tax code to tweak the economy, blissfully unaware of the impact on the real world of tax software, CPA training, forms design, etc. But in recent years, they've calmed down (the Rules Committee, that is). The more I think about this "small" change and the rationale for it compared with the number of software applications that will have to be modified, the more I feel like we've regressed.

This weekend, I was speaking with the man behind one popular freeware flight computer app and mentioned the change from 1 mile to 1/2 mile. He was quick to say that was a simple change. But his smile faded as he considered the various versions for which he would have to issue new releases.

Assuming that not every application will reflect the new AST radius, arguably this will have a negative effect on safety not just because of the tighter area but also because some of us will be reading numbers to get to .49 mile rather than just glancing at a blip on a TV screen as it approaches the circle.

FWIW, I survived photo targets (all aiming for the same exact point), 1/4 mile radii (a little better) and 1 mile radii (best). I fear our enthusiasm for adopting FAI rules has already triggered its first unintended consequence.

Chip Bearden
 




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