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Converting station pressure to sea level pressure

Remote Pilot (Part 107) practice question 15 of 25 on Weather / Effects on Performance. ACS element UA.III.B.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

QUESTIONA weather station at an elevation of 3,000 feet above sea level reads a barometric pressure of 26.95 inches of mercury. Using the approximation of 1 inch of mercury per 1,000 feet of elevation, what sea level pressure will the station report?

  1. A23.95 inches of mercury
  2. B29.95 inches of mercury
  3. C26.95 inches of mercury, uncorrected
Show the answer and explanation

Correct answer: B. 29.95 inches of mercury

  • A — incorrect The correction is added to the station reading, not subtracted; subtracting gives a value far below any sea level pressure.
  • B — correct Stations add approximately 1 inch of mercury per 1,000 feet of elevation: 26.95 plus 3.00 equals 29.95 inches of mercury.
  • C — incorrect Stations convert their readings to sea level pressure so that records and reports use a common standard; the raw reading is not reported.

BACKGROUND

Because weather stations are located around the globe at many elevations, all local barometric pressure readings are converted to a sea level pressure to provide a standard for records and reports. Each station converts its reading by adding approximately 1 inch of mercury for every 1,000 feet of elevation. The study guide's example is a station at 5,000 feet reading 24.92 inches of mercury, which reports a sea level pressure of 29.92 inches of mercury.

STUDY TIP

Work the conversion as elevation divided by 1,000, added to the station reading; check that the answer lands near the typical range around 29.92.

KEY POINTS

  • Station readings are converted to sea level pressure for standard reporting.
  • Add about 1 inch of mercury per 1,000 feet of station elevation.
  • Example: 24.92 at 5,000 feet reports as 29.92.

SOURCES

  • remote_pilot_study_guide.txt ch3b "Measurement of Atmosphere Pressure"
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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.