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Saturday practice at Hobbs NM



 
 
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  #11  
Old June 22nd 11, 04:20 AM posted to rec.aviation.soaring
Mike Schumann
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Posts: 539
Default Midair in Finnish nationals

On 6/21/2011 7:15 PM, Eric Greenwell wrote:
On 6/21/2011 1:56 PM, Mike Schumann wrote:


The reality is that FLARM, ADS-B, or any other GPS based technology is
useless in collision avoidance at close quarters. At the very best, the
position accuracy is only 50 ft and is only updated once a second.
Flying at 50 knots, you are traveling ~70 ft / second, so a lot can
happen between updates.

These systems are great in warning you about aircraft in your area that
you might otherwise not be aware of, and to give you an overview of how
many aircraft are in a particular gaggle and their relative altitudes,
but you absolutely can't rely on them for collision avoidance in a
thermal.


Is this conclusion based, at least in part, on your personal use of
FLARM in several contests?


I have not flown with FLARM, nor do I fly in contests. I did not mean
to imply that FLARM is not helpful in alerting you to targets that you
might not have otherwise seen. My point is that you can not rely on
FLARM at close quarters in lieu of keeping a good lookout and making
sure that you always keep in visual contact with any other gliders that
are close to you.

--
Mike Schumann
Ads
  #12  
Old June 22nd 11, 05:49 AM posted to rec.aviation.soaring
Eric Greenwell[_4_]
external usenet poster
 
Posts: 1,939
Default Midair in Finnish nationals

On 6/21/2011 8:20 PM, Mike Schumann wrote:
On 6/21/2011 7:15 PM, Eric Greenwell wrote:
On 6/21/2011 1:56 PM, Mike Schumann wrote:


The reality is that FLARM, ADS-B, or any other GPS based technology is
useless in collision avoidance at close quarters. At the very best, the
position accuracy is only 50 ft and is only updated once a second.
Flying at 50 knots, you are traveling ~70 ft / second, so a lot can
happen between updates.

These systems are great in warning you about aircraft in your area that
you might otherwise not be aware of, and to give you an overview of how
many aircraft are in a particular gaggle and their relative altitudes,
but you absolutely can't rely on them for collision avoidance in a
thermal.


Is this conclusion based, at least in part, on your personal use of
FLARM in several contests?


I have not flown with FLARM, nor do I fly in contests. I did not mean to
imply that FLARM is not helpful in alerting you to targets that you
might not have otherwise seen. My point is that you can not rely on
FLARM at close quarters in lieu of keeping a good lookout and making
sure that you always keep in visual contact with any other gliders that
are close to you.


I don't recall anyone suggesting you use only FLARM in that situation.
You said originally that it was useless in that situation, which seems
like too strong a statement if you don't have experience with FLARM. So,
have you modified your assertion, or am I missing some nuance?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
  #13  
Old June 22nd 11, 06:53 AM posted to rec.aviation.soaring
Mike Schumann
external usenet poster
 
Posts: 539
Default Midair in Finnish nationals

On 6/21/2011 11:49 PM, Eric Greenwell wrote:
On 6/21/2011 8:20 PM, Mike Schumann wrote:
On 6/21/2011 7:15 PM, Eric Greenwell wrote:
On 6/21/2011 1:56 PM, Mike Schumann wrote:


The reality is that FLARM, ADS-B, or any other GPS based technology is
useless in collision avoidance at close quarters. At the very best, the
position accuracy is only 50 ft and is only updated once a second.
Flying at 50 knots, you are traveling ~70 ft / second, so a lot can
happen between updates.

These systems are great in warning you about aircraft in your area that
you might otherwise not be aware of, and to give you an overview of how
many aircraft are in a particular gaggle and their relative altitudes,
but you absolutely can't rely on them for collision avoidance in a
thermal.

Is this conclusion based, at least in part, on your personal use of
FLARM in several contests?


I have not flown with FLARM, nor do I fly in contests. I did not mean to
imply that FLARM is not helpful in alerting you to targets that you
might not have otherwise seen. My point is that you can not rely on
FLARM at close quarters in lieu of keeping a good lookout and making
sure that you always keep in visual contact with any other gliders that
are close to you.


I don't recall anyone suggesting you use only FLARM in that situation.
You said originally that it was useless in that situation, which seems
like too strong a statement if you don't have experience with FLARM. So,
have you modified your assertion, or am I missing some nuance?


Useless was probably not the right word. This technology is obviously
very useful for identifying and warning a pilot about all equipped
aircraft that are potentially a threat. However, this technology does
not have the accuracy or update frequency to function as a reliable
collision avoidance system for aircraft that are operating at close
quarters.

--
Mike Schumann
  #14  
Old June 22nd 11, 09:35 AM posted to rec.aviation.soaring
jimboffin
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Posts: 15
Default Midair in Finnish nationals

I have flown with Flarm but do not yet have it fitted to my own glider
which I use in Nationals competition.

When flying XC in a Duo last year I nearly had a head on despite both
gliders being equipped with Flarm. I did not see the threat until too
late and I do not believe the other piot saw me as he took no avoiding
action. How can this be?

We were both flying at cruising speeds (closing at over 160kts) and
intercepted a short energy line from an angle of about 30 degrees. I
turned left onto the energy, he also turned left onto it but from the
other end. As I turned left the Flarm indicated a threat just left of
centre and below. Naturally I looked in that direction. This was my
mistake. The Flarm did not warn again and when I did see the threat it
was coming from my right. We had been flying towards each other with a
little lateral seperation and about 100ft vertically. He had now
turned right back onto track. My guess is that he was originally
warned that I was on his left as well and that was the way he was
looking. If this was the case he may have assumed that turning right
was OK.

This may be an isolated case but it says to me "If you fit Flarm keep
looking out and don't only look where it tells you to!".

I haven't flown in competition with Flarm but my experience includes
sharing thermals with up to 30 other gliders at a time - sometimes in
multiple cores with different bank angles and circle diameters. The
only way to avoid a collision is to look out all the time and fly
defensively. Flarm would only be a distraction in these circumstances.

I am afraid I am far from convinced of Flarms usefulness in either of
these cases.

Finally, in the UK Flarm is not compulsory in competition. Indeed our
rules expressly forbid exchange of data so Flarm has to be switched to
competition mode if used (and you know how to do it). I think this is
a mistake. If pilots were able to use the plane spotting features of
Flarm in competition it would be a definite advantage to fit it, and
all ambitious competition pilots would - including me despite my
reservations.

Jim


  #15  
Old June 22nd 11, 07:44 PM posted to rec.aviation.soaring
johngalloway[_2_]
external usenet poster
 
Posts: 46
Default Midair in Finnish nationals

The diagram on page 12 of this Powerpoint presentation on the Flarm
website shows very clearly the situations in which Flarm is most or
least useful:

http://www.flarm.com/files/basic_presentation_en.ppt

In busy contest thermal gaggles with lots of Flarmed gliders there are
so many alarms that you often can't tell or see which other glider is
Flarming you and have to regard it as a serious ongoing prompt to
vigorous Seeing and Avoiding - in the knowledge that the other pilot/
will also be getting an alarm and will hopefully be doing the same.
That is very useful in its own way but it is a very different type of
situational awareness from the use of Flarm in the cruise or
approaching a thermal gaggle.

I think that even if a magical Flarm were able to produce positional
and conflict information with zero error it would be impossible to do
much better for the case of busy similarly centered gaggles because
the gliders are continually making unpredictable centering and
avoidance corrections.

John Galloway
  #16  
Old June 23rd 11, 05:32 PM posted to rec.aviation.soaring
Peter Scholz[_3_]
external usenet poster
 
Posts: 78
Default Midair in Finnish nationals

Am 22.06.2011 20:44, johngalloway wrote:
The diagram on page 12 of this Powerpoint presentation on the Flarm
website shows very clearly the situations in which Flarm is most or
least useful:

http://www.flarm.com/files/basic_presentation_en.ppt

In busy contest thermal gaggles with lots of Flarmed gliders there are
so many alarms that you often can't tell or see which other glider is
Flarming you and have to regard it as a serious ongoing prompt to
vigorous Seeing and Avoiding - in the knowledge that the other pilot/
will also be getting an alarm and will hopefully be doing the same.
That is very useful in its own way but it is a very different type of
situational awareness from the use of Flarm in the cruise or
approaching a thermal gaggle.

I think that even if a magical Flarm were able to produce positional
and conflict information with zero error it would be impossible to do
much better for the case of busy similarly centered gaggles because
the gliders are continually making unpredictable centering and
avoidance corrections.

John Galloway


I had the pleasure of flying in a contest recently where all planes
were equipped with FLARM. Having several years of experience with flying
FLARM equipped gliders both in X/C and contest gaggle situations, I have
the impression that especially in gaggle situations the FLARM algorithm
has improved a lot with the current software version 5.xx. I had almost
no false alarms, and a few positive alarms in situations where an alarm
was appropriate.

I encountered one situation where I had no alarm, although the situation
might have developed into a close approach. This was a situation where I
was flying vertically underneath of another glider, with the vertical
distance becoming smaller. This is one of the "weak spots" because of
the usual position of the FLARM aerial the view below the aircraft is
obstructed. As the other glider was clearly visible, there was no real
danger though.

In the course of that contest, I had one situation en route where FLARM
provided important additional information. I already had spotted one
glider that was approching me on the same height in my 12 o'clock
position, and made a slight movement to the right. At that moment, the
FLARM was going off, showing me that there actually were two targets
approaching me. Scanning the horizon again I spotted the second plane,
and we all were able to pass each other in safe distances with very
little corrections of our course.

FLARM has its limitations, but it certainly can help to avoid dangerous
situations by giving the pilot additional informations on top of the
close lookout.
--
Peter Scholz
ASW24 JE


  #17  
Old June 24th 11, 09:37 PM posted to rec.aviation.soaring
Nyal Williams[_2_]
external usenet poster
 
Posts: 259
Default Midair in Finnish nationals

Does anyone know the name of the Ventus pilot?

At 16:32 23 June 2011, Peter Scholz wrote:
Am 22.06.2011 20:44, johngalloway wrote:
The diagram on page 12 of this Powerpoint presentation on the Flarm
website shows very clearly the situations in which Flarm is most or
least useful:

http://www.flarm.com/files/basic_presentation_en.ppt

In busy contest thermal gaggles with lots of Flarmed gliders there are
so many alarms that you often can't tell or see which other glider is
Flarming you and have to regard it as a serious ongoing prompt to
vigorous Seeing and Avoiding - in the knowledge that the other pilot/
will also be getting an alarm and will hopefully be doing the same.
That is very useful in its own way but it is a very different type of
situational awareness from the use of Flarm in the cruise or
approaching a thermal gaggle.

I think that even if a magical Flarm were able to produce positional
and conflict information with zero error it would be impossible to do
much better for the case of busy similarly centered gaggles because
the gliders are continually making unpredictable centering and
avoidance corrections.

John Galloway


I had the pleasure of flying in a contest recently where all planes
were equipped with FLARM. Having several years of experience with flying


FLARM equipped gliders both in X/C and contest gaggle situations, I have


the impression that especially in gaggle situations the FLARM algorithm
has improved a lot with the current software version 5.xx. I had almost
no false alarms, and a few positive alarms in situations where an alarm
was appropriate.

I encountered one situation where I had no alarm, although the situation


might have developed into a close approach. This was a situation where I


was flying vertically underneath of another glider, with the vertical
distance becoming smaller. This is one of the "weak spots" because of
the usual position of the FLARM aerial the view below the aircraft is
obstructed. As the other glider was clearly visible, there was no real
danger though.

In the course of that contest, I had one situation en route where FLARM
provided important additional information. I already had spotted one
glider that was approching me on the same height in my 12 o'clock
position, and made a slight movement to the right. At that moment, the
FLARM was going off, showing me that there actually were two targets
approaching me. Scanning the horizon again I spotted the second plane,
and we all were able to pass each other in safe distances with very
little corrections of our course.

FLARM has its limitations, but it certainly can help to avoid dangerous
situations by giving the pilot additional informations on top of the
close lookout.
--
Peter Scholz
ASW24 JE




  #18  
Old June 25th 11, 07:01 AM posted to rec.aviation.soaring
Peter Scholz[_3_]
external usenet poster
 
Posts: 78
Default Midair in Finnish nationals

Am 24.06.2011 22:37, Nyal Williams wrote:
Does anyone know the name of the Ventus pilot?


cited from previous entry:

Jock Proudfoot;775316 Wrote:
12-JUN-2011 15:58 LT
Schempp-Hirth Ventus 2a
Registration: OH-920
Fatalities: 1 / Occupants: 1
Airplane damage: Written off (damaged beyond repair)
Location: Renkajärvi, Hattula - Finland
Phase: En route
The second glider involved in the midair collision during the Finnish
National gliding competition in 15 meters class. The pilot was found
dead
after a long search.
The pilot of the other glider (ASG 29E) was able to escape with the
parachute. Both gliders crashed to the ground and were destroyed.
A collision-warning system (FLARM) was compulsory during the
competition.

Aalto Matti Ventus 2a
Teronen Olli ASG-29e


--
Peter Scholz
ASW24 JE
  #19  
Old June 25th 11, 08:52 PM posted to rec.aviation.soaring
Nyal Williams[_2_]
external usenet poster
 
Posts: 259
Default Midair in Finnish nationals

Thanks, I missed this.

I had feared that it might have been a friend I haven't heard from in
quite a while. Not so; sad news nontheless.

At 06:01 25 June 2011, Peter Scholz wrote:
Am 24.06.2011 22:37, Nyal Williams wrote:
Does anyone know the name of the Ventus pilot?


cited from previous entry:

Jock Proudfoot;775316 Wrote:
12-JUN-2011 15:58 LT
Schempp-Hirth Ventus 2a
Registration: OH-920
Fatalities: 1 / Occupants: 1
Airplane damage: Written off (damaged beyond repair)
Location: Renkajärvi, Hattula - Finland
Phase: En route
The second glider involved in the midair collision during the

Finnish
National gliding competition in 15 meters class. The pilot was

found
dead
after a long search.
The pilot of the other glider (ASG 29E) was able to escape with the
parachute. Both gliders crashed to the ground and were destroyed.
A collision-warning system (FLARM) was compulsory during the
competition.

Aalto Matti Ventus 2a
Teronen Olli ASG-29e


--
Peter Scholz
ASW24 JE


  #20  
Old June 26th 11, 12:16 AM posted to rec.aviation.soaring
Don Johnstone[_4_]
external usenet poster
 
Posts: 398
Default Midair in Finnish nationals

What we know:

Two gliders taking part in a competition collided
It was mandatory for all gliders flying in the competition to have FLARM
fitted.
One pilot survived and sadly, one died.

What we do not know:
What the flight profile was at the time of the accident, thermalling,
straight glide or final glide. (There has been much discussion of the
abilities of FLARM in a thermal but no evidence that the aircraft that
collided were thermalling)
The status of the FLARM devices, were they fully operational or in
Competition or Stealth mode or indeed working at all.
We do not know what warnings may or may not have been given to the pilots
and suggestions that competition pilots may ignore warnings in a
generalisation that I would find insulting if I were a competition pilot.
I am a competition director and I can say that most of the competition
pilots I have met are responsible and safety concious. Many things can
spoil your competition chances, having a mid air certainly will, so to
suggest that a pilot may ignore warnings is illogical.
What I would be interested to know is whether or not the status of the
FLARM units had any significance in this accident. I have expressed grave
doubts about degrading the performance of FLARM, even by a very small
amount, and the consequences of such action. I suspect that it may be some
time before the information is available.
A final thought, gliding is not dangerous in the same way that driving is
not dangerous per se. What a minority of pilots do can be dangerous and it
is up to all of us to ensure that if a pilot is dangerous he/she does not
get the opportunity to continue to be a danger to thers.

 




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