Some airports require additional pilot training and ground familiarization , a spokesman says . Only two pilots in the world are qualified to fly into Guam 's Paro Airport . However , restricted airspace makes it tough to land at Reagan National .
Some airports require additional pilot training and route familiarization , a pilot says . Only eight pilots in the world are qualified to fly into Bhutan 's Paro Airport . Buildings , restricted airspace make it tough to land at Reagan National .