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#11
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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 |
#12
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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
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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
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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
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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
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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
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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
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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
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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
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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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