On Wed, 25 May 2005 08:03:23 +1000, you wrote: <<< snip >>> > > The other item missing from the discussion is that ADS-b was not designed > for aircraft to aircraft crash avoidance, rather it is system designed to > replace the current SSR environment, anti collision was a bonus, as all the > aircraft squitter on a single channel and can be decoded on a receiver. If > the gliding community wants to adopt a separate anti collision system, I > would be just as interested in engineering that solution as I have been with > ADS-B provided a universal standard is adopted, which requires the current > companies that have systems to agree to release the protocol and the > manufacturers are indemnified from litigation should the system fail and > people die. ADS-B doesn't indemnify us either, but at least I can refer to > the 1,000 pages plus specifications!
Nigel, I also am not impressed that 1090 MHz was chosen as the vehicle for ADS-B. IMHO there would be greater range using a VHF frequency as you mentioned some other countries are using. My belief is that it was the RPT lot who convinced Airservices to use the Transponder frequency as they all had Mode S Transponders, and also TSO'd GPS systems, and it was just a matter of connecting the two and a bit of software for the Transponder. However, that has been the decision, and so we are stuck with it. I think it would be unwise to also introduce an incompatible system for glider use. This would leave gliders as undisplayed on power aircraft receivers (if they elect to fit them), and would also mean that the power aircraft were not visible to the glider pilot either. It is all very well to say that the Mark 1 eyeball is your best friend, (and I don't disagree) but if there is also some form of early warning of other traffic in the area, that eyeball can be much more useful, and the scan directed more accurately, giving the pilot a better chance of seeing a fast moving aircraft at a distance where evasive action can be taken. By all means develop a special receiver for gliders which has the facility to filter out very close threats, such as gaggles in thermals (pilot selectable, of course), but please don't advocate a system which is incompatible with ADS-B. Cheers, John G. _______________________________________________ Aus-soaring mailing list Aus-soaring@lists.internode.on.net To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring
