What is established for every 15 degrees of longitude for navigating purposes?

For every 15 degrees of longitude, time zones are established to facilitate navigation and coordination of time across different regions of the Earth. The Earth is divided into 360 degrees of longitude, and since it takes 24 hours for the Earth to complete one rotation, this means that each hour corresponds to 15 degrees of longitude (360 degrees divided by 24 hours equals 15 degrees per hour).

Time zones help standardize timekeeping across various locations, allowing for easier scheduling and communication for activities like navigation, travel, and international business. Each time zone usually spans 15 degrees of longitude, although political boundaries can cause variations. Understanding time zones is critical for pilots and navigators to accurately coordinate flight times and plans in relation to local time in various regions.

While flight levels, latitude lines, and magnetic variation are all important concepts in navigation, they do not pertain to the systematic division of the Earth for timekeeping purposes as time zones do.