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Night flight visibility measured by lighted objects

Remote Pilot (Part 107) practice question 21 of 22 on Operations / Physiology. ACS element UA.V.E.K8 · difficulty: recall. Want to answer it in a timed quiz? Use the Remote Pilot (Part 107) practice mode.

Question bank updated 2026-09-22

QUESTIONAt night, the flight visibility required by 14 CFR part 107 is measured by the average slant distance from the control station at which what may be seen and identified?

  1. AProminent lighted objects
  2. BProminent unlighted objects
  3. CObjects of any size, whether lighted or not
Show the answer and explanation

Correct answer: A. Prominent lighted objects

  • A — correct Section 107.51(c) states that flight visibility at night is the average slant distance from the control station at which prominent lighted objects may be seen and identified.
  • B — incorrect Unlighted objects are the yardstick § 107.51(c) gives for daytime flight visibility, not for night.
  • C — incorrect Section 107.51(c) limits the measure to prominent objects, and after dark specifically to lighted ones.

BACKGROUND

Section 107.51(c) requires a minimum flight visibility of no less than 3 statute miles as observed from the location of the control station. For purposes of that section, flight visibility means the average slant distance from the control station at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be seen and identified by night. The night half of the definition reflects the practical limit of human vision after dark: an object generally has to carry a light before a remote pilot can see and identify it. That is also why § 107.29(a)(2) requires a small unmanned aircraft operated at night to have lighted anti-collision lighting visible for at least 3 statute miles, with a flash rate sufficient to avoid a collision.

STUDY TIP

Memorize the two halves of the § 107.51(c) visibility definition as a pair: unlighted objects by day, lighted objects by night. Then tie the night half to the 3-statute-mile anti-collision lighting requirement in § 107.29(a)(2).

KEY POINTS

  • § 107.51(c) sets a minimum flight visibility of 3 statute miles observed from the control station.
  • By day the measure is prominent unlighted objects; by night it is prominent lighted objects.
  • § 107.29(a)(2) requires night anti-collision lighting visible for at least 3 statute miles.

SOURCES

  • 14 CFR 107.51(c)
  • 14 CFR 107.29(a)(2)
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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.