Aircraft leasing is a jewel in the crown of the Irish economic model for a number of reasons. Keeping it there is a challenge worth confronting.  When Tony Ryan imagined an aircraft leasing business back in the early 1970s, he was working with two Aer Lingus aircraft. Today, lessors based in Ireland own or manage over 10,000 aircraft. Air passengers to and from Ireland account for 1 per cent of the global market, yet Irish lessors manage over 30 per cent of the worldwide fleet.  The numbers involved in this business are eye-watering. The commercial aircraft fleet is valued at…