Sir, - Those who travel most frequently with Aer Lingus are now eligible to become members of a new "Elite" tier of their successful Gold Circle Club. One stated benefit to such members will be a guaranteed seat on any scheduled Aer Lingus flight "irrespective of whether or not the flight is full at the time of booking".While this concession is limited to two such guaranteed seats on each flight, Aer Lingus confirmed in a phone call that my understanding of this is correct - i.e., that two booked passengers may be "stood down" (my phrase) to facilitate this guarantee where necessary.I have advised the Air Transport Users Committee of this reprehensible intention and feel that prospective general Aer Lingus passengers should be aware of the matter, lest any who book a flight are later informed that the flight has been "overbooked". - Yours, etc.,R. J. Cloughley,Rathdown Park,Terenure,Dublin 6W.