Erm... Airfield BeacoN ALTernating (flashing) White & Green every 8 Seconds?
Aerodrome Ref Point is the position used for elevation measurements and Lat Long etc. - I believe it is worked out using a mean position between the centres of the longest runways or something. You shouldn't worry about it too much unless you have INS or GPS to navigate - then you need to be aware of the implications.
I think...
AB
PS What's an ERSA? (En-route Supplement something or what? UK or US?)
------------------
...proceeding below Decision Height with CAUTION...
[This message has been edited by AffirmBrest (edited 22 March 2001).]