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Cloud clearance under a low overcast

Remote Pilot (Part 107) practice question 23 of 34 on Regulations / Operating Rules. ACS element UA.I.B.K23 · difficulty: applied. Want to answer it in a timed quiz? Use the Remote Pilot (Part 107) practice mode.

Question bank updated 2026-09-22

QUESTIONA solid overcast layer with its base at 800 feet above ground level covers the operating area, and no structure is nearby. Applying the cloud-clearance and altitude limits of § 107.51, the highest altitude AGL at which the small unmanned aircraft may be flown is

  1. A400 feet AGL, the standard altitude limit
  2. B300 feet AGL, to remain 500 feet below the cloud
  3. C800 feet AGL, if the aircraft stays 2,000 feet horizontally from any cloud
Show the answer and explanation

Correct answer: B. 300 feet AGL, to remain 500 feet below the cloud

  • A — incorrect At 400 feet AGL the aircraft would be only 400 feet below an 800-foot cloud base, less than the 500 feet required by § 107.51(d)(1).
  • B — correct § 107.51(d)(1) requires at least 500 feet below the cloud: 800 − 500 = 300 feet AGL. That is lower than the 400-foot AGL limit in § 107.51(b), so 300 feet is the controlling ceiling.
  • C — incorrect Under a solid overcast the aircraft cannot be 2,000 feet horizontally from the cloud, and 800 feet AGL would also exceed the 400-foot AGL limit in § 107.51(b).

BACKGROUND

Section 107.51(d) requires the minimum distance of the small unmanned aircraft from clouds to be no less than 500 feet below the cloud and 2,000 feet horizontally from the cloud. These distances apply together with the altitude limit in § 107.51(b), which is 400 feet above ground level (AGL) away from structures. When a cloud layer is low, the cloud-clearance requirement can become the limiting factor: with a base at 800 feet AGL, staying 500 feet below the cloud caps the flight at 300 feet AGL, below the usual 400-foot limit. With a base at 900 feet AGL or higher, the 400-foot altitude limit would control instead. The remote pilot must apply whichever limit is more restrictive.

STUDY TIP

Subtract 500 feet from the cloud base and compare the result with 400 feet AGL; the lower number is the ceiling.

KEY POINTS

  • Cloud clearance: 500 feet below and 2,000 feet horizontally.
  • Ceiling under a low cloud base = base height minus 500 feet.
  • Use the more restrictive of the cloud-clearance result and the 400-foot AGL limit.

SOURCES

  • 14 CFR 107.51(d)
  • 14 CFR 107.51(b)
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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.