Primarily for general aviation discussion, but other aviation topics are also welcome.
By PaulisHome
FLYER Club Member  FLYER Club Member
#1591843
An interesting discussion.

Various threads to pick up:

1. Value of lookout. I reckon I'm pretty good at lookout. I see more than people I fly with. Yet still I see some aircraft very late. I don't know how many aircraft I don't see that get close. The ones I see are typically are the ones that are moving relative to me, which aren't the ones that are going to hit me. Those are stationary in my field of view, and more difficult to see, and I reckon there's a fair chance I wouldn't see one till too late. And sometimes, Flarm picks up people who are close that I haven't seen, or it takes me a long time to find someone who is quite close. Conclusion. Lookout isn't good enough, and I'm not actually 'good at it' at all (we're largely relying on the 'big sky' theory) and electronic conspicuity can help. Only help - it's not the complete answer, and there are all sorts of issues with it. I think that conclusion is supported by the evidence and the research. So when I say lookout is poor, I don't mean to say that we shouldn't concentrate on it (I spend a lot time trying to teach students to do it well), I mean that it needs to be supplemented.

2. Colours of aircraft. Again, go to the research. What you need is contrast. It's why the RAF paint their trainers black - it's a good contrast against the background, which they found having done the research. The evidence is that dayglow stripes don't do much - they may even break up the silhouette of the aircraft and make it more difficult to see. (Exception, possibly in the Alps, say, against a snowy background).

3. Strobes. OK - if you make them bright enough. But that's very bright. I can't find research on how much of a flashing light you need to stand out against a background, but I have done the sums on how much light battery operated strobes provide relative to the light you get on a normal day. And it's orders of magnitudes down on the background at 1km. And that is completely in line with actual experience which is that you see the aircraft first, then the strobe.

4. Painting composites. Yes, there are some composites that you can paint. But they are high temperature curing ones, not the ones that gliders and so on are currently made from. The operating manuals are pretty clear about keeping them white.

So, electronic conspicuity is a useful tool in the toolbox. This initiative is a very cost effective way of making two of the systems work with each other, which is why I'm working on it. [The cost of upgrading the whole current OGN network in the UK to the new receivers is around £14K. That's seven transponder installs, or maybe 14 ADSB in/out. Given that there are ~2000 aircraft with Flarm, and are likely to be 3000 with PAW by the end of this year, that's a very effective spend.]

Paul
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By mick w
FLYER Club Member  FLYER Club Member
#1591850
Gliders are always going to be difficult to spot , no matter what colour they are , but you can decrease your chances of collision dramatically , by not flying at Cloudbase when it's soarable , conspicuity markings do help at close range though. :thumright:
#1592698
Unfortunately since gliders became controlled by EASA we have to follow what the manufacturer puts in the maintenance manual, and for pretty much all of the gliders you will see cross-country that limits the areas that can be painted to small portions of the wingtips and rudder with no allowance for top surface or under surface. I don't know the exact reasons for this but that is the situation we're in.

So the simple, but not very satisfactory, answer is that painting the underside of the wing in high-vis would invalidate the Airworthiness Certificate. To change this you would need the manufacturer to issue a change notice - and good luck with that!

As has been pointed out this is now changing for some new gliders with the newer composites, but it will be a long time before significant number come in.

The fitting of tail mounted strobes is a similar position - there is no EASA approved mod available to do something like this on most existing types, although newer gliders can be so fitted (at manufacture). Typically the strobe installation is linked to Flarm/PowerFlarm so it activates when the Flarm system gets a threat warning - I've seen one of these working and it is very effective.

Having flown with and without hi-vis wing tip patches and observed other gliders my experience is they just break up the outline and you see the high-vis bit after you have seen the glider. You can get reflective mirror film to put on the tips & I wonder if that might work better?

Meanwhile I am supporting the effort to get PAW to carry Flarm signals, and I'm hoping the ADSB based systems start to become practical.
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By nallen
FLYER Club Member  FLYER Club Member
#1592701
DG Sailplanes say that:

‘You can apply color schemes to the following glider parts: all surfaces of the fuselage except the top of the fuselage to approx. 50° to the left and right of the center line, the undersides of wings and tail plane, the winglets and the upper sides of the wing tips. If you use light colors that fade towards the “forbidden” zone you can do quite a lot.’

(The official approval is here: https://www.dg-flugzeugbau.de/wp-content/uploads/filebase/Data/serviceinfos-en/2011-72-e.pdf)

Which suggests there is some scope for colour, and especially mirror foil -- whether this helps or not is another matter, of course.
By Lefty
FLYER Club Member  FLYER Club Member
#1592702
I mentioned "extra bright" strobe lights in an earlier post - but I should also mention wig-wag LED landing lights.
There are a couple of a/c based here wit these fitted - and they really do improve conspicuity - especially in hazy or poor viz conditions. You can see the wig/wag lights long before you can make out the shape of the aircraft itself. Any one else noticed this?
#1592749
ls8pilot wrote:... for pretty much all of the gliders you will see cross-country that limits the areas that can be painted to small portions of the wingtips and rudder
(my snip of Is8pilot's post)

Not on the gliders I've ever seen in the UK; they're white on the wingtips+rudder :wink: Sorry to harp on.
Rob
By PaulisHome
FLYER Club Member  FLYER Club Member
#1592801
Rob L wrote:
ls8pilot wrote:... for pretty much all of the gliders you will see cross-country that limits the areas that can be painted to small portions of the wingtips and rudder
(my snip of Is8pilot's post)

Not on the gliders I've ever seen in the UK; they're white on the wingtips+rudder :wink: Sorry to harp on.
Rob


Orange stripes are quite common on wing tips and rudder - either painted on or vinyl. It's often because such things are compulsory when flying down in the Alps, where there is a view that they help glider pilots see each other against a snowy background. Not everyone takes them off when they come back, though the evidence that they help to improve visibility without the snowy background is non existent (the RAF did a couple of quite detailed studies which showed the opposite).

Paul
#1592838
Rob L wrote:
ls8pilot wrote:... for pretty much all of the gliders you will see cross-country that limits the areas that can be painted to small portions of the wingtips and rudder
(my snip of Is8pilot's post)

Not on the gliders I've ever seen in the UK; they're white on the wingtips+rudder :wink: Sorry to harp on.
Rob


My point was that those are the areas you are allowed to paint - not that everyone did so. (If you look at the Tech Note for DG gliders referenced earlier you get some idea of the complexity of the rules)

The reason most of UK gliders do not paint this areas is because the RAF report referred to by other posters concluded that doing so actually reduced conspicuity in a UK environment. In fact at the time I know a number of people who removed such markings after that report was published. Gliders that visit the Alps will have hi-vis in these areas, which show up great against snow - but in UK conditions you need to be pretty close before you see them.

Please be assured most glider pilots take this very seriously - the main risk is glider:glider collision as we tend to congregate in the same bits of air & we are aware that the low profile of gliders makes them difficult to spot - even for other glider pilots.

If there was something that was proven to improve conspicuity and was practical and affordable I don't think there would be an issue in taking it up - you only have to look at the take-up of Flarm, it's very rare these days for me to encounter another glider on XC without them appearing on Flarm. The issue around wingtip markings is that the only study actually said they did not help.
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