What are the odds??? VERSUS Actual experience

[RC Steve Sterling]

Factor in that not every flight has two or more aircraft in the air at the
same time, which helps alittle.  The numbers are beginning to sound pretty
realistic, matching empirical experience. Expect a mid-air every 500-1000
flights when 2 or more aircraft are in the air.
  -----Original Message-----
  From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On
Behalf Of john
  Sent: Sunday, August 03, 2003 11:45 AM
  To: discussion at nsrca.org
  Subject: RE: What are the odds??? VERSUS Actual experience


  Well..    Number of rounds is not important in this unless you have
information about what round of the contest the crash occurred. Nor is the
number of years over which the experience is spread unless the contests are
still the same as 25 years ago, the numbers could be off because of the long
duration.



  100 contests x 25 contestants = 2500 opportunities, 2 midairs = 4
airplanes (pilots) involved = 4 in 2500 or 1 in 625.



  I think that is a little low. It really depends on what the flight
schedule is. Masters/FAI pilots tend to be more consistent in their flights,
staying at a fixed distance from the flight line. That would tend to
increase the number of midairs at contests with enough Masters or FAI pilots
to have them at both flight lines at the same time. And in fact the 1 midair
I have witnessed at a contest happened while both lines were flying Masters.



  By the way, that is 1 midair in 8 contests, about 25 average pilots for a
much worse 1 in 100 chance.



  John Petterson







  -----Original Message-----
  From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]
On Behalf Of Rcmaster199 at aol.com
  Sent: Sunday, August 03, 2003 12:09 AM
  To: discussion at nsrca.org
  Subject: Re: What are the odds??? VERSUS Actual experience



  David,

  I am looking at it from my point of view only: 100 contests
  give or take in 24 years, 25 contestants average each contest, 4 1/2
rounds average each contest, 2 mid airs. Per my experience, that's about 1
in 2500 tries, but it isn't probable. It's fact ;-)

  regards

  Matt






  Oops, correction:  The odds of you having a mid-air at a pattern contest
may be 1 in 56, not 1 in 560.  The odds of any contestant of having a
mid-air is 10 in 56, given the assumption that there are 56 pattern contests
each year in North America, and an average of 10 mid-airs per year.

  <<
  A more interesting question to me is, how offten do pattern planes collide
at contests?  I can control mid-airs outside of contests, but we are all
subject to the odds of a mid air if we participate in a contest.  Let's say
there are 10 mid-airs out of all the 8 NSRCA districts each year.    And
lets say there are 7 contests per district on average.  Then that is 56
contests.  Then the odds of having one mid air in a contest is 1 in 56.  Now
if there are 20 pilots average per contest, then your chance of mid-air is
1/(56 * 10) = one chance in 560 contest attendances (I think).




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