Sustainable aviation fuels may or may not eventually transform the carbon footprint of flying. But while a full tank is a way off, the mere whiff of a guilt-free future has got airline executives giddy. The annual meeting of Iata, the airlines’ global trade body, in Istanbul last week served up some exotic fare. Was that Willie Walsh, its director general, denouncing governments for “greenwashing”? And Marjan Rintel, boss of KLM and fresh from a Dutch court battle against government caps on Schiphol flights, outlining her purpose to “create memorable experiences on the planet we care for”? And Mehmet Tevfik…