How many classes of VORs exist?

There are three classes of VORs (VHF Omnidirectional Range), which categorize the navigational aid based on their operational characteristics and the range they cover.

The three classes are:

1. T-Area VORs: These are meant for use in terminal areas and generally provide a service range of about 25 nautical miles (NM) within a radius of about 12,000 feet altitude. They help pilots with approaches and departures around busy airports.

2. Low Altitude VORs: These provide navigation services at altitudes below 24,000 feet and have a service radius of up to approximately 40 NM. They are important for en-route flight navigation in less congested airspace.

3. High Altitude VORs: These are designed for aircraft operating at altitudes above 24,000 feet and can provide navigation coverage out to 130 NM or more. They serve higher altitude routes and help with long-distance navigation.

Each class serves distinct operational needs, ensuring that pilots have reliable navigational aids no matter their altitude or phase of flight. Other options suggesting a different number of classes do not encompass the established categorization used in aviation.