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Class D top altitude calculation

Remote Pilot (Part 107) practice question 3 of 21 on Airspace / Classification. ACS element UA.II.A.K1c · difficulty: applied. Want to answer it in a timed quiz? Use the Remote Pilot (Part 107) practice mode.

Question bank updated 2026-09-22

QUESTIONAn airport with an operational control tower has a field elevation of 1,200 feet MSL and is surrounded by Class D airspace of the general dimensions described in the Remote Pilot Study Guide. What is the approximate MSL altitude of the top of that Class D airspace?

  1. A3,700 feet MSL
  2. B2,500 feet MSL, since Class D is charted in AGL
  3. C5,200 feet MSL
Show the answer and explanation

Correct answer: A. 3,700 feet MSL

  • A — correct Class D generally extends to 2,500 feet above the airport elevation; 1,200 feet plus 2,500 feet equals 3,700 feet MSL.
  • B — incorrect Class D is charted in MSL, and 2,500 feet is the height above the airport, so the field elevation must be added.
  • C — incorrect 5,200 feet MSL would result from adding 4,000 feet, which is the Class C figure, not the 2,500 feet used for Class D.

BACKGROUND

The Remote Pilot Study Guide describes Class D airspace as generally extending from the surface to 2,500 feet above the airport elevation, charted in mean sea level (MSL). Converting that limit to MSL requires adding the airport's field elevation. For a field elevation of 1,200 feet MSL, the top of Class D is about 3,700 feet MSL. The actual boundaries of each Class D area are individually tailored, so the calculation gives the general figure only.

STUDY TIP

Practice converting 'above the airport elevation' limits to MSL by adding the field elevation; the same method works for Class C.

KEY POINTS

  • Class D generally tops out 2,500 feet above the airport elevation.
  • Add the field elevation to express the top in MSL.
  • 1,200 feet plus 2,500 feet gives about 3,700 feet MSL.

SOURCES

  • remote_pilot_study_guide.txt Chapter 2 "Class D Airspace"
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MORE ON AIRSPACE / CLASSIFICATION

SkyDrill is not affiliated with the FAA. This is an original practice item based on 14 CFR part 107, 14 CFR part 89, and the FAA Remote Pilot – Small UAS Study Guide (FAA-G-8082-22). Regulations and handbooks are revised; confirm details against the current edition.