Originally Posted by Comjam: "What effect do you think a mid-air between a non-squwaking glider and a commercial aircraft is going to have on your sport? A lot more damaging than having to fit Mode S i'd imagine".
Let's try the situation from a different perspective:
"What effect do you think a mid-air with a commercial aircraft flying in uncontrolled airspace, where it is well known that not all traffic cannot be seen, is going to have on commercial operations?"
Some of the challenges that light aviation (not just glidng) is facing with the feasibility of Mode-S include:
(1) There often isn't the space to install a transponder in glider or microlight (panel space on some gliders is very limited). Where will a parascender fit their kit?
(2) Mode-S requires power. Not all gliders have batteries, let alone ones that'll operate continously for twelve hours or more.
(3) Mode-S doen't provide autonomous interoperability as it requires either TCAS to be also fitted or to be in contact with ATC (and not all gliders have radios). Trials have taken place in Europe with gliders using FLARM, which is a GPS-based collision avoidance system which gives you warning of all potential collision risks with other suitably equipped aircraft and overcomes the need for a controller to be monitoring traffic.
(4) No research seems to have been done to show what degradation in performance having an external antenna fitted has. If you have a nice big engine dragging you through the sky then this isn't a problem. Take a look at how finely polished glider wings are and you'll see that a 'small' decrease in performance actually makes a big difference.
(5) Does anybody have proof that having a transmitter constantly broadcasting within a few feet of you doesn't have any effect on your body ? The effect of long term exposure to magnetic/radio transmissions still isn't fully understood. And before anybody says "oh but we all use mobiles and they're ok", I'd suggest doing some proper research1
(6) Cost is an issue - A vintage glider is probably worth about £1000. A Mode-S transponder, once a low consumption version is available, is likely to cost several thousand pounds. That's aside from the annual tests, maintenance, calibration, approval, etc. Cost is an issue that could actually be overcome by charging commercial users a small premium for the ability to use Open airspace. This premium could then be used to pay for the development, hardware and installation in every GA aircraft, glider, microlight and parascender.