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Weather Observation & Reporting Flashcards

7 cards from real CTO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Weather Observation & Reporting flashcards as text
  1. A controller notices the barometric pressure has dropped below 28.00 inches Hg. What action is required?

    Answer: Issue a low altimeter setting alert to all aircraft

    Controllers must alert pilots when the altimeter setting drops below 29.00 inches Hg, and especially note extremely low settings such as below 28.00 in Hg.

  2. What does a microburst wind shear alert from LLWAS typically include when transmitted to pilots?

    Answer: Location, wind gain or loss, and recommended action

    A microburst alert includes the location relative to the runway, wind gain or loss value in knots, and controller-issued advisory.

  3. Which type of fog forms when moist air moves over a surface that is colder than the air's dew point?

    Answer: Advection fog

    Advection fog forms when warm, moist air moves horizontally over a cooler surface, causing condensation near the ground.

  4. An aircraft reports moderate icing in cloud. Which ASOS sensor measures this condition?

    Answer: ASOS does not measure icing; PIREPs are the primary source

    ASOS cannot detect airframe icing; pilot reports (PIREPs) are the primary means of identifying icing conditions in flight.

  5. How is blowing snow (BLSN) differentiated from drifting snow (DRSN) in a METAR?

    Answer: Blowing snow reduces visibility and rises above 6 feet; drifting snow stays below 6 feet

    BLSN is reported when wind-driven snow reduces visibility and rises to 6 feet or more AGL, while DRSN stays below 6 feet.

  6. What visibility criterion triggers a mandatory SPECI when conditions improve after having been below minimums?

    Answer: Visibility rises to 3 SM or more after having been below 3 SM

    A SPECI is required when visibility rises to 3 SM or above after having been reported below that threshold.

  7. A controller receives a SIGMET for severe icing. According to ATC procedures, what must the controller do?

    Answer: Issue the SIGMET information to affected aircraft in a timely manner

    Controllers are required to promptly relay SIGMET information to potentially affected aircraft, regardless of flight rules.

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Sources & references

Exam facts on this page (fees, format, dates, passing scores) are checked against these official sources; the date is our last check. Editorial policy

  1. ecfr.gov — Score validity, renewal, eligibility, retake policy · verified Oct 2026
  2. faa.gov — Test delivery, passing score · verified Oct 2026