What are the typical base altitudes for Class E airspace around many non-towered airports?

• A. 1,000 ft AGL or 2,000 ft AGL
• B. 400 ft AGL or 500 ft AGL
• C. 700 ft AGL or 1,200 ft AGL
• D. 2,000 ft AGL or 3,000 ft AGL

Answer: (C)

Class E base heights around many non-towered airports are set to support IFR transitions while keeping the low-altitude airspace predictable for VFR. If the area has an instrument approach, Class E typically begins at 700 ft AGL to provide a controlled path from lower altitudes into the approach procedures. In areas without such approach density, the default base is 1,200 ft AGL. So, you’ll commonly see Class E starting either at 700 ft AGL or at 1,200 ft AGL. The other base heights listed aren’t the standard floors used for this scenario, since 400–500 ft AGL or 2,000–3,000 ft AGL do not represent the typical bases around these airports.