PowerFLARM leeching comments

On Thursday, October 18, 2012 2:20:25 PM UTC-7, Alexander Swagemakers wrote:
In the first seasons of competition flying with FLARM in Germany a few people were turning on stealth mode, especially if they did not have a display to get any tactical data. Turning FLARM off was also observed regularly. Now I hardly notice anyone using stealth mode anymore. The initial fear of having a competitive disadvantage seems to have run dry.



Flarm is far from giving you a clear picture of the thermals ahead. On average the range is smaller than the distance you can see with your eyes, so your best bet for finding a thermal is still looking outside. There are occasions where Flarm brings another glider to your attention you would otherwise have missed but it is far from being a reliable thermal finder.



FLARM range is extremely variable. I fly a lot of club gliders with different antenna installations and I have seen gliders with carbon fuselage with hardly 2km of reliable range for collision avoidance. Especially to the rear a carbon fuselage will often completely block the Flarm signal so that a target flying right behind you will sometimes not be visible. In other cases I have had peak ranges up to 25km which usually only last long enough to display the target for a few seconds. A very good installation should give you fairly reliable contacts up to 4 - 6km and irregular peaks of up to 8-16km. Remember that the range always depends on antenna installation in both gliders. Even with a perfect installation you will not see some Flarm equipped gliders even on short range.



Flarm will give you some benefits in competition flying. Besides the advantages mentioned above it is particularly good for tracking what is happening around. You can marker specific targets to keep track of your team mate or see your progress against a selected competitor. It’s not like the range and reliability is good enough to leech someone outside your eyesight but you get an occasional fix of your marked competitor a few km ahead (or behind) giving you some sense of whether you are gaining or losing ground. Personally I enjoy this because it makes gauging my own performance a little bit easier.



The most useful feature of Flarm is still collision avoidance. You get a really good situational awareness of what is happening around you. Bad surprises of a glider appearing out of nowhere, hardly happen anymore.

This is consistent with my experience over 7 days of contest flying with PF.. It is occasionally modestly helpful out on course in keeping track of competitors who are within a few miles of you. I found four specific instances where it was helpful:

1) Running down a group of pilots who started a couple of minutes ahead of me. On a blue day in particular, getting the right first climb can save a couple of minutes by keep you in touch with markers a bit better. On one occasion I was able to close on a group of very good pilots by about 2-3 minutes over the first 30-40 miles. They were just outside of visual range most of the time, so PF made a difference.

2) Calling attention to where there might be a good climb ahead - this was most often useful when making long-ish glides between areas of lift. With a big enough field of competitors, depending on the course, you randomly end up with situations where you'll pick up someone climbing in front of you - for me it happens a couple of miles before the naked eye can make the target out. It's possible that you might pick them up anyway, but just knowing where to point the nose to find a climb at the end of a long glide was modestly helpful and worked for me a couple of times.

3) Choosing a direction coming out of a turnpoint. Gliders collect at turpoints so I occasionally had a couple of targets out in front of me at turns. Should I take the deviation out to the cloud street or head straight down the courseline? I found myself using trends in altitude differential over several minutes to gauge climb much more than the PF transmitted climb rate, which is too noisy to be useful beyond "climbing or not?" questions.

4) Marking my progress against known competitors. I wrote down the PF codes for specific competitors as I became aware of them. On a couple of occasions on long legs I made different courseline decisions from other pilots and was able to mark progress as they came back into range dozens of miles later - this didn't really yield useful tactical information, but it made me feel good to come back in range with a rival having made some ground on them.. Discovering the opposite is a bit disheartening, but motivating.

I'd say in total it made maybe 1% difference in total points over a contest, though I'll never know for sure if it saved me from flying into a hole or led me astray in specific situations. A bigger search radius for other gliders out on course certainly doesn't hurt and I found it increased my enjoyment by making racing slightly less solitary.

Most importantly, PF called my attention to a handful of collision targets that I am certain I would never have seen without it. It's sobering to realize how many potential midairs in the past must've been avoided by nothing more than random chance.

9B