airnav ranges long distance ?

[acars45]

Good morning in my airnav set up with my super gainer antenna and slim jim pre amp im getting ranges around 200 -230 then see attached I seem to got  track in Scotland 400 miles from my location in Orpington kent
my question is this possible the attached map shows this but im not sure
would you be so kind to let me know is this right .
Look forward to your repiles
Paul

[CoastGuardJon]

Hi Paul, I used to get A/C at 330-340 NM with the standard antenna, sited on flat roof about 210' asl looking west out over Atlantic Ocean, these were at a height of 40,000' so if A/C was 45 or 50,000 feet, 400 NM could well be possible IMO, we've discussed "ducting" or "skips" before which doesn't seem to happen with any predictability at 1090 MHz.   If you know your antenna height asl, it should be possible to calculate the theoretical distance.   I'm not that good a mathmetician to work it out for you!      HTH

[acars45]

If you look at the attached map with the ranges over Scotland North sea does not look right

[RodBearden]

You can get your theoretical range easily - see this post: http://www.airnavsystems.com/forum/index.php?topic=8229.msg108318#msg108318