Switzerland has the notoriously difficult approach over the mountains into Lugano Airport. In England, it’s London City’s steep 5.5-degree glideslope to touchdown that can really test an aviator’s skills. And of course, the dead-end approach into Greenland’s Kangerlssaq Airport in the Sondrestrom Fjord can be a doozy when the weather turns bad. But just which are the most challenging airports in the U.S., those with instrument approach procedures that elicit disproportionate numbers of white-knuckle tales from the pilots who’ve flown them? That’s the question Max-Viz of Portland, Ore., will try to answer this summer as it seeks input from pilots, mainly from the corporate ranks, to help it determine the 10 toughest approaches in America. The company will then fly each of the approaches with its enhanced vision system (EVS) to prove to aviators and potential customers the value of being able to see at night and in poor visibility when terrain is perilously close. Max-Viz plans to make public the results of its assessment in time for this fall’s NBAA Convention, where video from each of the flights will be available on DVD for anyone interested in learning more about enhanced vision.