Confessions of a Flarm Follower

On Tuesday, December 29, 2015 at 10:54:41 PM UTC-5, XC wrote:
On Tuesday, December 29, 2015 at 10:01:03 PM UTC-5, Andy Blackburn wrote:
On Tuesday, December 29, 2015 at 4:40:49 PM UTC-8, XC wrote:

Biggest loser, though, is the sport of soaring. We lose our heros. These are the great personalities that make this sport attractive young pilots. This sport was built by bold pilots who did great things, who consistently demonstrated an uncanny knack for finding thermals when no one else could.

I have to say when I read this it sounded like a description of Ramy flying OLC from Monterrey to Truckee and back or Gordo and Jim Payne doing crazy distance flights in the wave.

Racing is really about tactical optimization under uncertainty, which is why you find so much gaggling and other tactical behavior - quite a different sport from OLC altogether. Flarm adds some dynamism to the pure tactical game of yore by spreading out the field. It's not clear that wanting to use Flarm tactically is much more than an emotional security blanket. It may in fact result in more spreading out of the field, more independent action and more heroic flying.

Funny how things go full circle sometimes.

9B

A sailplane contest should determine who is the best glider pilot. In fact that is the first rule in the rule book. We all know what skills it takes whether pure cross country, badges, OLC, or competition. That's why in the past contest winners were also record holders.

The rules should reward those who possess these better soaring skills. Now we are getting into this BS that a glider contest is about something else, a new set of skills. Further proof that we have a fuzzy picture of what our sport is about.

If we can't even get together on what our sport is about, how can we expect bright young people to be sold on it.

XC

I concur with XC. You guys that support Flarm for safety reasons is fine, but how about looking outside the old fashioned way and make your own decisions. My current career position has me looking inside the cockpit a large percentage of the time, technology is great, but is really limits pilot awareness especially outside the cockpit. You can keep your contests, and I'll be looking outside when I'm flying my glider for fun...

On Tuesday, December 29, 2015 at 6:40:49 PM UTC-6, XC wrote:
Thank you, John. Someone finally is admitting that FLARM is being used tactically.

I don't think I have ever used the word leeching in any of my posts. Rather, I believe this business of being able to see contest numbers and their established climb rates is bad for sailplane racing.

The losers in all this are those who are confident enough in their abilities to lead out, who have honed their skills at looking at the sky and finding the best thermals available and those who can best convert that rising air into altitude. In other words, the losers are those who could best navigate a given sky if they were the only ones flying that day. The losers are those who are the best at soaring.

The winners are those who use a heads down FLARM display to drive hard to catch up to gaggles or gliders outside of visual range, who then use the choicest thermals marked by others to enhance their score. This is not necessarily the leeching scenario described by many. Instead they can jump from best thermal to best thermal without find their own. They may not win, although this is quite possible, but they can consistently do well, even though they would do much worse were they to attempt the same flight without markers.

Biggest loser, though, is the sport of soaring. We lose our heros. These are the great personalities that make this sport attractive young pilots. This sport was built by bold pilots who did great things, who consistently demonstrated an uncanny knack for finding thermals when no one else could. It makes me sick that people want to replace or replicate this kind skill with a FLARM display and then expect us to clap for them at the end of the contest.

XC


Well said.

WB

Thanks for sharing John. I hope one day glide computers can tell you "that guys climb is strong enough to compensate for the detour".

Interesting thread topic. Some issues...

DEFINTION OF A "RACE"
r�s/
noun
1.
a competition between runners, horses, vehicles, boats, etc., to see which is the fastest in covering a 'SET' course.
"I won the first 50-lap race"
synonyms: contest, competition, event, heat, trial(s)
"Sasha won the race"

Humm the jeopardy theme...now...and read on...

NOT A RACE FOR 800 Alex...

"This competiton is won by the glider pilot who achieves the fastest average speed flying while anywhere literally anywhere they want in series of pilot option, 60 mile diameter turn "areas" (2800+ square miles of possible flying area in "each" 30 mile radius turn area) within a "pseudo" irrelevant minimum time. For example, if you start an hour later/earlier, and atmospheric conditions become batter/worse, this time variable alone will likely determine the winner by a massive margin...."

Answer: What is a clown show?

I won't bother to the jeprody joke for the HAT tasks.

You implied that we "race" during US contest tasks ;-). Who are you trying to kid? In the US, with 97% timed, subjective tasks (wide area TAT, HAT, insufficiently long MAT) and "Sasquatch rare" assigned tasks (3% and falling) which "allow" for additional distance in the turns. The USA offers exactly ZERO set tasks that are remotely racing around a set "race" course (all competitors negotiating the same track and challenges) by any definition. This says nothing of the start being unlimited and basically freeform in terms of competitions (couple hours variance between start times is not rare) and that competitors can start up to 10 miles apart, out the top, etc.

Especially in the US, in reality we loosely "time trial" around a free form area (average 40 mile diameter) and simply try to aqcuire more distance within a pseudo set time "limit." We run far more HATs (slang for the infamous one or zero turn MATs) than assigned tasks...which are sadly "molested" by utterly pointless modifications (extra distance incentives and associated collision risks). The only hard data regarding US tasking and the DEFINTION of racing is that we actually NEVER race the same track. It is always different, never set and therefore NOT A RACE! A pure fact! NEVER the same track. Unlike the majority of the soaring world which RACES roughly 50% real racing assigned tasks. The EXACT SAME TRACK TO THE MILLIMETER.

Your description of your Flarm behavior is refreshing, but also no real justification for rushing the entire US soaring community, fresh off a 5 year campaign to sell $2500 POWERFlarms, into stealth mode. To me, little of what you describe is truly tactical. Even the thermal save via a BVR flarm hit would, IMO, rarely be successful. I'll bet that 80-90% of pilots who tried that same play end up on the ground or even worse off (stuck longer)! It often would be better to simply focus on common terrain thermal triggers to find a last stand thermal so far below the other gliders last known Flarm location. What you are describing, IMO, is informational "comfort" and "fun." Most Flarm users don't have the fancy displays (LX9xxx or CNi) to truly have a broad tactical picture. Most, probably simply tune out or don't bother trying. I agree (and have recently described) that it is fun to see if I have stayed in the same realm as another group a mile away for example when we get in range (1-2 miles). This quick blip serves to break up the loneliness of US tasks which are often far more like individual OLC flying (alone) than an actual race where working to gain on competitors in order to judge your performance while, wait for it.............."racing!"

US tasks are, in reality, more of a game of hide and seek. In most tasks I have flown, I have spent enormous portion of them completely alone with very little Flarm activity. Hours without a wing flash. I think this is true for many I imagine. That is not racing. It's something else. Its a weather game. It's also the design of the US tasking philosophy. There is no set race track (ever) in US soaring. Not even the 3% ATs are set tracks. We simply make it up as we go for most tasks, with the priority being broad weather analysis decisions. Rarely are challenged with difficulty getting in and out of an assigned turnpoint efficiently. In the US, it's typical to simply run to the end of the good clouds and turn there. Even our assigned tasks allow for as much as a 2 mile separation at each turn! Not a race. A distance contest. Often up to 20 extra miles are available in a US "assigned????" task. We just can't resist molesting the only pure racing task.

Also, you utilize the advanced (beautiful) LX9000 (I believe) which has the luxury of a fairly powerful tactical display of Flarm information and opponent telemetry data (so I am told). This probably makes the visibility of Flarm targets more fun to monitor.

Even in your best effort to "admit your sins," I think you have really struggled to describe anything that has resulted in your improving your results based on an ability to build a BVR understanding of other competitors locations. You just enjoy not being totally alone all day and waiting until 8-9pm to see what happened. I tend to agree with you. I see Flarm the as short wave radio surprise communication on a usually lonely task!

And you are completely correct, this kind of technology will be abundantly available, for pennies on today's dollar and probably 10x more capable in 3-5 years. Perhaps sooner. ADSB, cheaper ADSB, micro ADSB (RC hobby grade), some other new tech, improved satellite trackers with target tracking displays and other integrated systems (gen 3 satilite tracking services), improved cellular networks with greater range and azimuth range, new cheaper POWERFlarm competitors, perhaps other cheap tools and tech driven by hang/para glider development.

This jeanie is not going back in the bottle easily or for long, if at all. The purely PHILISOPHICAL and almost pointless debate about what "the spirit of soaring" will be irrelevant almost before the ink is dry on the new comp mode mandate.

This will probably end up just like the old smartphone ban in 1-3 years. A waste of effort. I'm all for competition mode if US pilots are truly winning US contests by exploiting Flarm tactically. I just don't see any evidence of that and my own experience tells me that is simply not possible. Information is not always high value, actionable tactical information. On the other hand it is quite fun when it works and is what everyone who bought these fancy devices paid a bunch of money for.

With US "isolationist" tasking philosophy, Flarm is far less of a concern than the uber competitive and sophisticated teams of Europe, flying a far higher percentage of assigned racing tasks, as well. I still think we should have held off a year or at least until we have some reports from Europe. And I still worry a situational awareness related safety issue looms...

Or, maybe somebody here knows that somebody who is an absolute master of Flarm "following" tactics and has used it to advance up the score sheet (philisophically violating the secret SSA oligarch soaring code of conduct). I doubt it, but this is the only possible reason which justifies what I see happening so soon, next season.

Sean

Interesting thread topic. Some issues...

DEFINTION OF A "RACE"
r�s/
noun
1.
a competition between runners, horses, vehicles, boats, etc., to see which is the fastest in covering a 'SET' course.
"I won the first 50-lap race"
synonyms: contest, competition, event, heat, trial(s)
"Sasha won the race"

Humm the jeopardy theme...now...and read on...

NOT A RACE FOR 800 Alex...

"This competiton is won by the glider pilot who achieves the fastest average speed while flying literally anywhere they wish in series of pilot option, 60 mile diameter turn "areas" (2800+ square miles of possible flying area) within a "pseudo" irrelevant minimum time. For example, if you chose to start an hour later that your competiton, and atmospheric conditions become generally better or worse, this start time variable alone will likely determine the winner by a large margin...."

Answer: What is a clown show?

I won't bother to do the Jeopardy joke for the HAT tasks. That would be downright painful for many...

You sorta implied/snuck in that we "race" during US contest tasks ;-). Who are you trying to kid? I can't let they go untested. In the US, with 97% timed, subjective tasks (wide area TAT, HAT, insufficiently long MAT) and "Sasquatch rare" assigned tasks (3% and falling) which "allow" for additional distance in the turns. The USA offers exactly ZERO set tasks that are remotely racing around a set "race" course (all competitors negotiating the same track and challenges) by any definition. This says nothing of the start being unlimited and basically freeform in terms of competitions (couple hours variance between start times is not rare) and that competitors can start up to 10 miles apart, out the top, etc.

Especially in the US, in reality we loosely "time trial" around a free form area (average 40 mile diameter) and simply try to aqcuire more distance within a pseudo set time "limit." We run far more HATs (slang for the infamous one or zero turn MATs) than assigned tasks...which are sadly "molested" by utterly pointless modifications (extra distance incentives). The only hard, relevant fact regarding US tasking and the DEFINTION of racing is that we actually NEVER race the same track. Every pilot, in fact, flies a different course and therefore is not RACING anyone! They are trying to find a better route thru the maze. A pure fact! NEVER the same track. Unlike the majority of the soaring world which RACES roughly 50% real racing assigned tasks. The EXACT SAME TRACK TO THE MILLIMETER. No variance in distance flown. Amazing.

Your description of your Flarm behavior is refreshing, but also no real justification for rushing the entire US soaring community, fresh off a 5 year campaign to sell $2500 POWERFlarms, into stealth mode (negating 90% of the instruments advertised function). To me, little of what you describe is of high or even moderate tactical value. Even the thermal save via a BVR flarm hit you described would, IMO, rarely be successful. I'll bet that 80-90% of pilots who tried that same play end up on the ground or even worse off (stuck longer)! It often would be better to simply focus on common terrain thermal triggers in order to find a "last stand" thermal so far below the other gliders last known Flarm location. What you are describing, IMO, is informational "comfort" and "fun." A toy! Most Flarm users don't have the fancy displays (LX9xxx or CNi) to truly realize a broad tactical picture. Most, probably tune out or don't even bother trying to track long range targets. I agree (and have recently described) that it is fun to see if I have stayed in the same realm as another group when we get in range (1-2 miles). This quick blip serves to break up the loneliness of US tasks which are often far more like individual OLC flying (alone) than an actual race where working hard to gain on competitors in order to maximize your short term performance while, wait for it.............."racing!"

US tasks are, in reality, more of a game of hide and seek and explore. In most tasks I have flown, I spend enormous portion of them completely alone with very little Flarm activity. Hours without a wing flash or a glimpse of a fellow glider. I think this is true for many pilots I imagine. That is not racing. It's something else. It partially a weather management game.. It's also the design goal of the US tasking philosophy. There is never a set race track from R all pilots in US soaring. Not even the 3% ATs are set tracks. Im most tasks, we simply make it up as we go, with the priority being broad weather analysis decisions and often pilot discretion to add several extra turnpoints (even less of a set race than a typical wide area TAT!). Rarely are we challenged with efficiently getting in and out of an assigned turnpoints when the clouds do not perfectly line up to take us there. In the US, it's typical to simply run to the end of the good clouds and turn there (turn area). Even our assigned tasks allow for as much as a 2 mile separation at each turn! Not a race. A distance contest. Often a US AT allows up to 20 extra miles to be added. We just can't resist molesting the only pure racing task on a SET track.

Also, you utilize the advanced (beautiful) LX9000 (I believe) which has the luxury of a fairly powerful tactical display of Flarm information and opponent telemetry data (so I am told). This probably makes the visibility of Flarm targets more fun to monitor.

Even in your best effort to "admit your sins," I think you have really struggled to describe anything that has resulted in your improving your results based on an ability to build a BVR understanding of other competitors locations. You just enjoy not being totally alone all day and waiting until 8-9pm to see what happened. I tend to agree with you. I see Flarm the as short wave radio surprise communication on a usually lonely task!

And you are completely correct, this kind of technology will be abundantly available, for pennies on today's dollar and probably 10x more capable in 3-5 years. Perhaps sooner. ADSB, cheaper ADSB, micro ADSB (RC hobby grade), some other new tech, improved satellite trackers with target tracking displays and other integrated systems (gen 3 satilite tracking services), improved cellular networks with greater range and azimuth range, new cheaper POWERFlarm competitors, perhaps other cheap tools and tech driven by hang/para glider development.

This jeanie is not going back in the bottle easily or for long, if at all. The purely PHILISOPHICAL and almost pointless debate about what "the spirit of soaring" will be irrelevant almost before the ink is dry on the new comp mode mandate.

This will probably end up just like the old smartphone ban in 1-3 years. A waste of effort. I'm all for competition mode if US pilots are truly winning US contests by exploiting Flarm tactically. I just don't see any evidence of that and my own experience tells me that is simply not possible. Information is not always high value, actionable tactical information. On the other hand it is quite fun when it works and is what everyone who bought these fancy devices paid a bunch of money for.

With US "isolationist" tasking philosophy, Flarm is far less of a concern than the uber competitive and sophisticated teams of Europe, flying a far higher percentage of assigned racing tasks, as well. I still think we should have held off a year or at least until we have some reports from Europe. And I still worry a situational awareness related safety issue looms...

Or, maybe somebody here knows that somebody who is an absolute master of Flarm "following" tactics and has used it to advance up the score sheet (philisophically violating the secret SSA oligarch soaring code of conduct). I doubt it, but this is the only possible reason which justifies what I see happening so soon, next season.

Sean

On Tuesday, December 29, 2015 at 6:09:21 PM UTC-5, John Cochrane wrote:
So, it's time to fess up. I have used flarm tactically in contests. I enjoyed it. And I think it increases, not decreases, the "spirit" of the sport..

How: One soupy, incredibly hard blue day at Perry, I had (as usual) screwed up my determination that this time, I was not going to foolishly go out on my own. I was going to stick with the gaggle as you're supposed to do on such days. That determination lasted about half way down the first leg, when I spied a bird over the town to the right. The bird started flapping, and here I am all alone again.

After a long slog at about 1000 feet and rounding the second turn, I saw two gliders circling on my flarm. Out of ideas, I headed that way. Eventually I saw a flash of wings a few miles ahead and 2000' up. Usually coming in that much under other gliders does not work, but I was out of ideas. I lost them visually, but flew right to where the Flarm said they were. Bingo, the thermal had another bubble in it, and up we go. Day saved, and, it turned out, eventually won.

Another, much stronger day, I was flying with a group of gliders. Two lines suggested themselves. Everyone else went right, but I went left. Over the rest of the leg, I was able to watch how they did vs. how I did. Eventually, my line ended -- it proved they were right. Oh well, I was able to head over and meet up again, and the group went together through the big blue hole. I would have lost them visually, but knowing what was going on was a lot of fun.

I tend to be impatient, often leading out. At minden nationals the glides are very long. After leading out on a blue day, one often wonders, did the others follow, or are they staying behind? It was very useful strategically to know that the gaggle had indeed followed me, so I would have help if things got tough up ahead. Also, it means I could go a bit deeper in the cylinder and reestablish myself. It was also good to know on my disastrous last day, that I had led out once too often, and now was completely on my own to dig out of this mess. Knowing there is nobody there is useful too!

At Nephi, a group of us used flarm radar to coordinate a team of 4 without a lot of radio contact. Did your team mate find a thermal? Boy, it is a lot easier to look quickly at the flarm radar than radio calls.

Ok, I'm out of that closet. Yes, this is a useful technology. Is this kind of behavior a disaster to the "spirit" of soaring?

Sailplane racing has always been tactical. Following other gliders, using their lift, is the heart of the tactical game, especially in world contests and especially in weaker conditions. The issue is not flarm following vs. no following. The issue is looser flarm following vs. much tighter visual following.

As my stories suggest, one of the biggest tactical uses of flarm is that you can spread out. If you want to keep contact with the gaggle in case things get tough, you do not have to slavishly stay a few hundred feet away; you do not have to slavishly stare at them to not lose sight of them. You can go try something else, you can lead out, you can stop for a better thermal, all knowing that it will be easier to keep in contact if you need it.

"Leeching" is not the same as "following." Leeching is the art of staying very close, in visual range. Flarm eliminates leeching because it makes it possible to follow and work together at much bigger distances. Flarm encourages thinking for yourself, leading out, trying a different cloud. To my mind, this is a much better "spirit" than the intensely tactical and concentration-absorbing visual tracking that you have to do without flarm.

I also flat out enjoy the greater situational awareness. Since when is flying around in the soup, unaware what everyone else is doing, only to find out at 9 pm once the scores are in, such a great spirit? I look forward to the day that ADS-B shows us where everyone is, and I know how I'm doing throughout the race.

So, as I see the controversy, this is just about who wins and who loses.

Winners: people who can imaginatively adapt tactics to use new technology, which mostly involves flying at a greater distance from markers.

Losers: people who have invested a lot of time and effort learning the skills of visually-coordinated tactical flying, whether finding targets in the start area, following specific gliders, learning the discipline to stick with the gaggle when needed, escaping others who attempt to follow, knowing where others might go, intercepting radio calls to team captains, and so forth.

No wonder the IGC is up in arms -- a generation of hard-won skills is about to go out the window.

Say I, good riddance. I freely admit this is blatant self-interest. I'm in the first category. I just can't bring myself to spend a whole soaring day looking at and following other gliders, so I never got good at visually-coordinated tactical skills that will now go out the window.

But I also claim that the spirit of the sport is much better if we can fly much more loosely, and Flarm allows that, without throwing away the chance of winning the contest.

John Cochrane BB

My friend John has finally come out of the closet. I've been waiting for this because, knowing John, we would eventually hear about why he thinks Flarm radar is a good thing for our competitions. He hasn't resorted to the safety panic mongering of many and makes an interesting case.
I'll provide some other insights and opinions with the hope that the personal shots about age, paranoia, or protecting my status can be skipped by those that don't agree with me.
I've used radar in the same ways as John, except for the team flying he describes. As a result of the experiences with this it is my opinion that Flarm radar can be a very powerful and useful tool with the potential to have a meaningful affect on individual performance and result scores. John well describes some of those cases.
The reality is that radar is most useful tactically as a following tool, either by direct following or, by using the information from the leading pilot(s) to decide to follow, or diverge. There is very little, if any, benefit to the leading pilot. The effect of this is that following becomes more useful and important in tactics.
The ability to break away by the leading pilot(Jerzy excepted) is meaningfully reduced. No longer does he have to get out of visual range, he must get out or radar range. 2-3 miles becomes 6 or more. This will only become more as the value of this too gets better understood and the tools get better with longer range.
Radar also makes team flying hugely easier. John likes this because he really enjoys this. Some others will also. Many, will not.
There is one unstated assumption in the scenarios John describes. That is that we all give information via Flarm and get it back.
As a demonstrated useful tactic, one can play what I would call "hide and seek".
This involves selectively blanking the A antenna while using the B for reception. This allows the pilot to receive at somewhat reduced effectiveness while providing no tactical information out. Unfortunately this has a profound affect on the safety benefits we all bought the tool for. There are lots of ways to do this, such as the old antenna in the side pocket next to the foil wrapped snack bar trick, and others that some of us that have thought about this, and maybe already used, have come up with.
I know this is happening now to a small degree, but predict it will become more prevalent in the future. It is reported to be much more common in Europe than the US, but they are ahead of us on adoption and tactics.
A well specified Competition mode could, in my view, reduce the motivation to disable the safety benefits we want. I would, for purposes of discussion, suggest the following characteristics understanding that the Flarm folks would need to do a lot of rethinking:
Mode effective radius of 5km vs. current 2km. This would provide much enhanced warning range. It is also sort of matches the useful visual range for ID and climb rate of competitors. There seems to me to be little benefit to choking the range below useful visual, and, I suspect most will agree, some strong negatives.
Retain the no ID and climb rate concept with one exception. Provide the ID if the glider that Flarm has determined is a conflict.
Limit information in only. This would allow other users not in Competition mode the full level of protection. This has meaningful issues with respect to ensuring effectiveness of the mode, because it relies on only on the receiving glider to be properly configured.
Yes I know you can hide another Flarm, but the antenna has to go somewhere and I would be willing to risk an occasional(likely very rare) cheater.
Provide ID of all gliders that Flarm sees in a head on situation(10 degrees L&R?)at full range.
What I am describing could give us close to full safety benefit, while keeping the tactical benefits to what I think are a tolerable trade off, and reducing the motivations toward greater levels of cockpit technology to leverage this tool.
Flame suit on.
Happy New Year to all.
UH

Seems to me that most forms of racing have always been about who can tweak/manipulate/out think/out engineer, the competition. That's why racing breeds technological improvements.

Racing that freezes improvements is usually called "one design" and encourages an absolute level field.

I suppose we must decide what path the sanctioned classes are choosing.

Lane

.... the safety benefits we all bought the tool for.


Hah, you're just being diplomatic with that one UH.

Does anyone really doubt that the hard core Flarm pushers have been using "safety" as a cover? I think most of the Flarm advocates have never really cared about collision avoidance as the PRIMARY function of Flarm. "Safety" is mostly just a bludgeon to be used against the debate opposition.

My belief is that tactics to gain advantage through Flarm and to deny competitors information, or perhaps even to broadcast misinformation, will severely degrade the safety function of Flarm far more than any "stealth/competition" mode does.

On Wednesday, December 30, 2015 at 8:56:42 PM UTC-5, wrote:

Your statement "Flarm pushers have been using "safety" as a cover" is a pretty bad accusation directed towards people who brought Flarm to the USA.

Another of your comment "Flarm advocates have never really cared about collision avoidance as the PRIMARY function of Flarm"

Your above comment is simply ridiculous and offending to many people. You might consider rethinking before you post next time.

On Wednesday, December 30, 2015 at 8:22:30 PM UTC-6, Andrzej Kobus wrote:
On Wednesday, December 30, 2015 at 8:56:42 PM UTC-5, wrote:

Your statement "Flarm pushers have been using "safety" as a cover" is a pretty bad accusation directed towards people who brought Flarm to the USA.

Another of your comment "Flarm advocates have never really cared about collision avoidance as the PRIMARY function of Flarm"

Your above comment is simply ridiculous and offending to many people. You might consider rethinking before you post next time.

Sorry if I offended you Andrzej, I apologize for not making it clear that I was not referring to the developers or the vendors of Flarm. My post was directed only towards those pilots who have vigorously pushed Flarm under the somewhat transparent guise of "safety" when what they really care about is tactical advantage. Those who protest vehemently against stealth mode on the basis of reduced safety, give away their true agenda when they refuse to at least acknowledge that tactical use of Flarm raises the potential for degradation of safety. Do we know that the current stealth mode, or a future "competition" mode will reduce safety more than increased head-down time or intentional suppression of antennas, or..?

I am not against Flarm. I have flown with Flarm in contests for it's stated purpose as a collision avoidance tool and found it useful.