I definitely agree that both IATA & ICAO codes should be combined (that was the whole point of my post). I'm biased with preferring the IATA code as that was what I used for 90% of my time in aviation. I still think that the majority of people involved in commercial passenger carrying would likely only use IATA codes, Travel Agents, Airline Reservations staff, Passenger Service Airport Staff, Baggage Loaders etc plus of course, the passengers themselves. That said, having both IATA and ICAO codes the same whether they be 3 or 4 letter is the objective and if that was to be the current ICAO codes, then so be it, it would be better than the current double coding. I could go further in saying there should be similar for actual Airlines codes, why are there again separate codes? One last point, a non-IATA Airline can still use an IATA 'approved' code, I worked for quite a few that did exactly that.