The attack on Istanbul’s Ataturk airport on 28 June was the latest incident over the last year to highlight the terrorist threat to civil aviation. The requirement to prevent such attacks in the future will place a growing premium on security cooperation between the public and private sector, particularly in light of the range of options available to those intent on targeting aviation interests and the expected growth in passenger numbers. Incidents over the last year also serve as a reminder of the principle of proportionality; whatever the extent of security cooperation or the countermeasures adopted, nothing is capable of delivering perfect protection.