Airspace

(Refer to Figure 59.) South-east of Metamora, inside the outer magenta circle of the Toledo Class C, an obstacle is charted 988 over (255). A remote pilot inspecting it keeps the small UA within 400 feet of it. What is the highest altitude allowed, and is the UA inside the Class C there?

Figure 59 from the FAA Airman Knowledge Testing Supplement — Figure 59, FAA Airman Knowledge Testing Supplement (FAA-CT-8080-2H). Open full size to zoom. Not for navigation.

A1,388 feet MSL, which is below the 2,000-foot MSL floor of this Class C sector
B400 feet AGL, because the structure allowance does not apply beneath a Class C shelf
C1,388 feet MSL, but the UA is in Class C from the surface because it is inside the outer circle

Show answer and explanation

Correct answer: A. 1,388 feet MSL, which is below the 2,000-foot MSL floor of this Class C sector

The obstacle's top is 988 feet MSL and its height is 255 feet AGL. Within a 400-foot radius, part 107 allows flight up to 400 feet above the structure's top: 988 + 400 = 1,388 feet MSL. The outer Class C sector is labeled 47 over 20 (ceiling 4,700, floor 2,000 feet MSL), so the UA stays below the Class C.

A. Correct. Within 400 feet of the structure the UA may climb to 988 + 400 = 1,388 feet MSL. The outer sector is labeled 47 over 20, so Class C starts at 2,000 feet MSL there.
B. Incorrect. The part 107 allowance to fly up to 400 feet above a structure has no exception for airspace beneath a Class C shelf.
C. Incorrect. Only the inner circle (47 over SFC) starts at the surface. Between the circles the floor is 2,000 feet MSL.

Marked on Figure 59: Obstacle 988 (255) south-east of Metamora.

Marked on Figure 59: Toledo Class C labels 47/SFC and 47/20.

Source

FAA Chart Users' Guide (Aeronautical Chart User's Guide), complete, VFR Chart Symbology, Airspace Information, Class C Floor of Class C in hundreds of feet MSL

FAA Chart Users' Guide (Aeronautical Chart User's Guide), complete, VFR Terms and Symbols, Land Features (Terrain) and Obstructions The AGL height is in parentheses below the MSL elevation.

14 CFR Part 107 (eCFR), §107.51(b) (1) Is flown within a 400-foot radius of a structure; and (2) Does not fly higher than 400 feet above the structure's immediate uppermost limit.

A practice question written from official FAA publications, not a question from the FAA knowledge test.

(Refer to Figure 59.) South-east of Metamora, inside the outer magenta circle of the Toledo Class C, an obstacle is charted 988 over (255). A remote pilot inspecting it keeps the small UA within 400 feet of it. What is the highest altitude allowed, and is the UA inside the Class C there?

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