Friday, 3 May, 2002, 13:21 GMT 14:21 UK Air Miles 'threaten dollar's dominance'Air Miles currently in circulation are said to be worth $500 billion - making them the second biggest "currency" after the dollar. Air Miles facts American Airlines set up first airline reward scheme 21 years ago, called the "Advantage Travel Programme" "Air Miles" originates from the UK 13 years ago Name now franchised to third parties, including British Airways who has owned the UK Air Miles operation since 1994 Source: Air Miles UK At its current rate of growth the stock of miles could overtake the dollar within...