First of all, thanks Markus for your report. One borderline off-topic clarification:
> He took the > ADS-B (Automatic Dependent Surveilance Broadcast) system as an example, Use of the word "the" here is a bit of a problem. ADS-B is a generic term, a bit like GNSS vs GPS, Glonass, etc. There are three ADS-B systems which I know of being trialed in various parts of the world. One is UAT, being developed by the US parcel carriers (UPS is the "ring-leader" I think) which works on a discrete frequency (980 MHz, if I recall correctly). Another is an extension of GPS-squitter which puts a GPS position and other information on the end of the normal mode S response from a standard modern aircraft transponder (1060 MHz, again IIRC). This is being pushed by the US FAA. The third is VDL (VHF data link) mode 4 which was being trialed in Europe by the Swedish civil aviation authority, Swedish airlines, Lufthansa, gliders in Sweden, etc. VDL mode 4 has been adopted legally in the Russian federation though I've no idea of the implementation state. Some airliners on long oceanic routes call in their positions automatically via satellite. This also comes under the ADS-B banner and is in pretty widespread use, particularly over the Pacific. Regretably, Eurocontrol is pushing for mode S transponders in all aircraft, rather than ADS-B which is, in my humble opinion, a complete disaster for all of general aviation and the military and anybody else who makes a habit of flying around without full air traffic control but that's a rant for another list, I'm just not sure which :-). Anyway, all I'm trying to say is that any discussion about what "ADS-B" does or doesn't do with time had better be clear about which system they are talking about. Of course, if different systems coexist but choose different time scales it's likely that the areas where they try to interoperate will be where the real leap second problems happen. Ed.