How often are WAC (World Aeronautical Charts) updated?

World Aeronautical Charts (WAC) are designed for long-range navigation and are vital resources for pilots flying at lower altitudes or for cross-country flights. They provide essential information including terrain features, airspace classifications, and navigational aids.

Typically, WACs are updated every six months to ensure that the data remains current and reflects any changes in airspace, navigational aids, and other relevant information. This semi-annual update cycle is considered optimal to keep the charts reliable for flight planning and navigation.

The other options suggest more frequent or less frequent updates, which would not align with the requirements for accuracy and currency needed for operational safety in aviation. A six-month cycle strikes a balance between the need for timely updates and practical considerations regarding the production and distribution of these charts.