The floor of Class B airspace at Air Park-Dallas Airport is

The floor of Class B airspace at Air Park-Dallas Airport is

• A. 3000 feet MSL
• B. 6000 feet MSL
• C. 1000 feet MSL
• D. 0 feet MSL (surface)

Answer: (A)

Class B airspace is built in layers called shelves, each with its own floor. The floor is the lower boundary of that shelf, shown on the chart in feet MSL. The innermost core often has a floor at the surface, but surrounding shelves start higher up, like 3000 feet MSL, 6000 feet MSL, and so on. If the floor of the Class B around Air Park-Dallas is 3000 feet MSL, that means airspace within that outer shelf begins at 3000 feet MSL. Anything operating at or above that altitude inside that ring is in Class B and requires ATC clearance to enter. Below 3000 feet, you’re outside that shelf and would be in Class E or G, depending on the exact location. The other options would correspond to different configurations (either a shelf at the surface for the inner core, or floors at other altitudes for other shelves). The charted base in this case is 3000 feet MSL, which is why that choice is the best one.

Class B airspace is built in layers called shelves, each with its own floor. The floor is the lower boundary of that shelf, shown on the chart in feet MSL. The innermost core often has a floor at the surface, but surrounding shelves start higher up, like 3000 feet MSL, 6000 feet MSL, and so on.

If the floor of the Class B around Air Park-Dallas is 3000 feet MSL, that means airspace within that outer shelf begins at 3000 feet MSL. Anything operating at or above that altitude inside that ring is in Class B and requires ATC clearance to enter. Below 3000 feet, you’re outside that shelf and would be in Class E or G, depending on the exact location.

The other options would correspond to different configurations (either a shelf at the surface for the inner core, or floors at other altitudes for other shelves). The charted base in this case is 3000 feet MSL, which is why that choice is the best one.