Though they have “no global positioning satellite, no air traffic controls and no pilots, ” they routinely fly at an altitude of 10,000 feet [3,000 m] at night, using navigational skills more sophisticated than modern aircraft.
Kuigi neil „pole GPS - i, lennujuhtimisseadmeid ega piloote ”, lendavad need rändurid igal aastal öösiti 3000 meetri kõrgusel, navigeerudes palju paremini kui moodsad lennukid.