Just a guess, but I think the reason the idle RPM is so high, is due to the engine `windmilling` hence energy required, and drag produced.
When we shut one down on the 340, it will usually spin at around 20% N1 from memory (@300 kt)
<response to below post>techman, if you ehh? is re my post, then to answer your question, Yes I have heard of it, however flight idle, or approach idle as I think Airbus refer to it, is only commanded when the gear is down, or two stages of flap are selected (from memory).
[This message has been edited by jtr (edited 26 September 2000).]