In fact, WAAS makes your GPS LESS accurate in Europe, because it blindly applies corrections which are irrelevant. This is more likely to occur in the air due to the improved 'over the horizon' view of the satellites.
The European equivalent of WAAS is EGNOS, which consists of 1 extra satellite (#33). The system is due to go live this year and is fully compatible with your WAAS GPS.
Sat 33 is currently transmitting a test signal with a 'DO NOT USE' message. Magellan receivers decode the flag and ignore the signal. Garmin receivers (consumer versions) see the flag and ignore it (i.e. try and use the signal), on the grounds that the correction signal may be valid and you shouldn't be using their consumer units for anything important anyway!
EGNOS and WAAS will probably become redundant when Galileo is fully operational in a few years. The increased number of satelites and more advanced coding should acheive VNAV atleast as good as WAAS.
[edited to add that by redundant I mean 'a useful backup system' and not 'a waste of space and money - throw it all away' !]
Last edited by Tall_guy_in_a_152; 22nd January 2004 at 06:21.