While airway beacons assisted aerial navigation on specific routes, most pilots at that time depended on dead reckoning, generally using automobile road maps (such as those from oil companies or commercial mapmakers), railroad tracks and landmarks to find their way.[1][5] Jeppesen purchased a ten-cent notebook and started writing down detailed notes about his routes.[3] He even climbed hills to determine their height and collected telephone numbers of farmers willing to provide weather reports.[4] Word got around about his "Little Black Book", and soon he was giving copies to his fellow pilots.[2] Jeppesen was the first to design enroute procedures, let down procedures, approach procedures, and the all-important, missed approach procedure.[citation needed] If the weather was bad and visibility dropped to zero, if the Jeppesen Airway Manual had a missed approach procedure for that particular airport, the pilot could use it to determine what heading to turn to, how to miss any mountains and how high to climb. Today, all airlines use the Jeppesen Airway Manual for navigation.[citation needed]