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Commercial pilot · ACS CA.I.C · lesson pack

Weather Information (Commercial)

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Why this one matters

Weather accidents in commercial flying usually begin on the ground: a paying passenger, a schedule, and a forecast that is almost good enough. The commercial pilot who decides with written personal minimums, and diverts early without apology, keeps the customer, the airplane and the certificate.

1 · Know these cold

  • •Before beginning any flight, become familiar with all available information concerning it. For a flight under IFR or not in the vicinity of an airport, that includes weather reports and forecasts, fuel requirements, alternatives if the flight can't be completed, and known ATC delays; for every flight, runway lengths and takeoff and landing distances.(14 CFR 91.103(a)-(b))
  • •Sources: Flight Service (1-800-WX-BRIEF or online), aviationweather.gov and approved providers. Use reports (METAR, SPECI, PIREP) and forecasts (TAF, GFA, AIRMET, SIGMET) together.(AIM, Chapter 7, Section 1 (meteorology))
  • •A forecast is a best guess with a time window. Plan around the worst reasonable case for your arrival time, not the best.(Aviation Weather Handbook (FAA-H-8083-28A))
  • •Set personal minimums before you see the weather, and keep them when a customer is waiting.(Risk Management Handbook (FAA-H-8083-2A))
  • •Datalink NEXRAD is a mosaic: total latency is commonly 5-15 minutes or more, and the weather can be 15-20 minutes older than the age shown. Use it to stay well clear of storms, never to pick a path between cells.(AIM 7-1-9 and 7-1-11 (FIS-B and in-cockpit weather); NTSB Safety Alert SA-017)
  • •Divert early, while you still have fuel, daylight and options. A diversion is a normal outcome, not a failure.(Risk Management Handbook (FAA-H-8083-2A))
  • •Avoid known or forecast icing unless the airplane is approved for it, and severe turbulence in any airplane.(Aviation Weather Handbook (FAA-H-8083-28A))

2 · The lesson

Sources and products
  • Briefings: a standard briefing is the complete one, for a flight not yet briefed; an abbreviated briefing supplements or updates one you already have; an outlook briefing is for a flight more than 6 hours away and doesn't replace a standard briefing closer to departure.(AIM 7-1-4; AC 91-92)
  • Reports: METAR and SPECI (airport observations), PIREPs (what pilots actually found: tops, icing, turbulence). Forecasts: TAF, the Graphical Forecasts for Aviation, winds and temperatures aloft.(Aviation Weather Handbook (FAA-H-8083-28A))
  • AIRMETs (moderate hazards): Sierra, ceilings under 1,000 feet or visibility under 3 SM over a wide area, and extensive mountain obscuration; Tango, moderate turbulence, sustained surface winds of 30 knots or more, and non-convective low-level wind shear; Zulu, moderate icing and freezing levels.(Aviation Weather Handbook (FAA-H-8083-28A); AIM 7-1-6)
  • SIGMETs (severe hazards, any aircraft): severe or extreme turbulence or clear air turbulence and severe icing not tied to thunderstorms, widespread dust or sandstorms below 3 SM, and volcanic ash. Convective SIGMETs: lines of thunderstorms, embedded thunderstorms, thunderstorms covering a large area at high intensity, and severe surface weather (tornadoes, large hail, surface winds of 50 knots or more).(Aviation Weather Handbook (FAA-H-8083-28A); AIM 7-1-6)
  • Surface Analysis Chart: fronts, pressure systems and station plots, the big picture. Ceiling and Visibility Analysis (CVA): current ceilings and visibilities between reporting stations.(Aviation Weather Handbook (FAA-H-8083-28A))
  • Convective Outlook (AC) from the Storm Prediction Center: where thunderstorms, and severe ones, are expected over the next days; use it for planning the day, not the route minute by minute.(Aviation Weather Handbook (FAA-H-8083-28A))
Meteorology on the route
  • Know the hazards for each phase: fog and low ceilings at departure and arrival, fronts and convection en route, mountain wave and turbulence over terrain.(Aviation Weather Handbook (FAA-H-8083-28A))
  • Stability decides the weather: stable air gives smooth air and poor visibility; unstable air gives turbulence, good visibility and convection.(Aviation Weather Handbook (FAA-H-8083-28A))
  • Temperature and dew point close together mean fog or low clouds are likely, especially as the air cools at night.(Aviation Weather Handbook (FAA-H-8083-28A))
  • Heat and moisture: the sun heats the ground and the ground heats the air; air cools about 2°C per 1,000 feet when dry and less when saturated. Cooling to the dew point brings clouds, fog and precipitation.(Aviation Weather Handbook (FAA-H-8083-28A))
  • Air masses and fronts: a cold front brings a narrow band of showers or thunderstorms and gusty wind shifts; a warm front, wide areas of low ceilings, rain and poor visibility; stationary and occluded fronts mix the two.(Aviation Weather Handbook (FAA-H-8083-28A))
  • Clouds tell you the air: cumulus means unstable air and bumps; stratus, stable air and low ceilings; towering cumulus and cumulonimbus, convection to avoid.(Aviation Weather Handbook (FAA-H-8083-28A))
  • Thunderstorms need moisture, unstable air and a lifting force. Stay at least 20 nm from severe ones. Microbursts are short, violent downdrafts with wind shear: a headwind gain followed by a strong downdraft and tailwind, near the ground.(Aviation Weather Handbook (FAA-H-8083-28A))
  • Wind shear can come with fronts, thunderstorms, temperature inversions and mountain wave; expect it near the surface when strong winds sit over calm air.(Aviation Weather Handbook (FAA-H-8083-28A))
  • Icing needs visible moisture at or below freezing: check the freezing level, and know that the worst icing is often just below it in freezing rain, or in clouds near the tops of cumulus.(Aviation Weather Handbook (FAA-H-8083-28A))
  • Frost on the wings, even thin, disrupts the airflow and can stop the airplane from flying: remove it all before takeoff.(Aviation Weather Handbook (FAA-H-8083-28A))
  • Obstructions to visibility: haze, smoke, dust and volcanic ash reduce visibility, especially looking into the sun, and ash can stop an engine.(Aviation Weather Handbook (FAA-H-8083-28A))
Datalink and onboard weather
  • FIS-B over ADS-B gives METARs, TAFs, NEXRAD and more for free, but the radar picture is a mosaic and can be well behind real time.(AIM 7-1-9 and 7-1-11 (FIS-B and in-cockpit weather))
  • Onboard weather equipment (lightning detectors, onboard radar) has its own limits: know what yours shows and what it misses.(Your airplane's POH/AFM)
  • Limits of the products: a METAR or SPECI is one point at one moment; AWOS and ASOS can miss clouds and weather beyond their sensors; PIREPs are sparse and subjective; a TAF covers about 5 statute miles around one airport and is amended as it changes.(Aviation Weather Handbook (FAA-H-8083-28A))
  • In flight, update with Flight Service, ATC's hazardous weather broadcasts, Center Weather Advisories and PIREPs, and give PIREPs yourself. ATIS is for the airport you're arriving at, not the route.(AIM, Chapter 7, Section 1 (meteorology); Aviation Weather Handbook (FAA-H-8083-28A))
Go, no-go and divert
  • Write personal minimums (ceiling, visibility, wind, crosswind, night) and decide against them, not against the customer’s schedule.(Risk Management Handbook (FAA-H-8083-2A))
  • Set a divert trigger before you leave: a ceiling, a visibility, a fuel number or a time. When it happens, divert.(Risk Management Handbook (FAA-H-8083-2A))
  • Known or forecast icing and turbulence aloft are reasons to change the plan, the altitude or the day.(Aviation Weather Handbook (FAA-H-8083-28A))

Want it all on one page, with scenarios? Read the full lesson.

3 · Say it out loud

Answer each one out loud, then check yourself and mark how it went.

  1. Remember Recall it

    “What weather sources would you use before a commercial cross-country?”

  2. Understand Explain why

    “Why shouldn’t you use datalink NEXRAD to fly between storm cells?”

  3. Apply Use it on a flight

    “Your charter passengers are at the airport. The destination TAF shows a ceiling right at your personal minimum, falling at your arrival time. What do you do?”

4 · Common mistakes

  • Letting the schedule set the minimums.

    Pressure lowers standards one flight at a time.

    Instead: Write minimums down and decide before you meet the customer.

  • Treating datalink radar as real time.

    It can be many minutes old.

    Instead: Use it for wide avoidance only.

  • Diverting late.

    Fuel and daylight run out.

    Instead: Set a divert trigger before departure.

5 · Quick check

Answer, then reveal. Flag anything you want to see again.

  1. 1. Which regulation requires you to know the weather before a cross-country?

  2. 2. Which AIRMET covers icing?

  3. 3. What does a close temperature and dew point spread suggest?

  4. 4. Why is datalink NEXRAD limited?

  5. 5. What is a divert trigger?

  6. Scenario6. A paying passenger asks you to “just try it” in weather below your minimums. What do you say?

Trained it? Now prove it: practice weather information (commercial) out loud with our examiner.

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Connect it

One situation that runs across this lesson and its neighbors in the same ACS area. Decide first, then check.

Connect it · Preflight Preparation

A week after your checkride, a friend's company offers to pay you to fly three employees to a meeting in a rented 172. They want to leave at 6 a.m.; you have a full workday before.

Can you take the job, and what else matters? Decide, then see the worked answer

It turns on who provides the airplane and who has operational control. If you rent the 172 and provide the company pilot plus airplane, that's carrying persons for compensation, and offering it (holding out, under AC 120-12A) makes it common carriage. That needs an operator certificate under Part 119, with the flight run as an on-demand Part 135 operation, so decline. The lawful version is the company renting or leasing the airplane in its own name, holding operational control, and paying you only to fly it. That's a Part 91 flight, and your commercial certificate lets you be paid as its pilot (the FAA's Green (1993) and Ferris (1990) interpretations draw this line). None of the 119.1(e) exceptions, such as student instruction, nonstop commercial air tours under 91.147, ferry or training flights, or aerial work like banner towing, covers flying a company's employees to a meeting. 91.409(b) requires a 100-hour inspection for an aircraft carrying any person, other than a crewmember, for hire, or used for flight instruction for hire in an airplane the instructor provides. Company employees flown on the company's own business, without being charged, aren't passengers for hire in that sense, so it doesn't automatically apply to the Part 91 version; check the airplane's inspections either way. Then check yourself: a second-class medical for commercial privileges, a current flight review, and three takeoffs and landings in the last 90 days to carry passengers. Without an instrument rating, 61.133(b)(1) bars carrying passengers for hire on cross-countries over 50 NM or at night. Part 91 has no duty or rest limits, so fatigue is yours to manage: run IMSAFE honestly, and a 6 a.m. report after a full workday needs a real sleep opportunity first. If you won't get one, decline or move the departure. Pressure to please a client makes the call harder, not different.

14 CFR 61.23, 61.56, 61.57, 61.133, 91.409(b), 119.1; AC 120-12A; Risk Management Handbook (FAA-H-8083-2A)

Brings together: Pilot Qualifications · Airworthiness Requirements · Human Factors

Teaching this? The instructor lesson plan →

Study aid, not FAA guidance. Sources: Aviation Weather Handbook (FAA-H-8083-28A); Aeronautical Information Manual (AIM); Risk Management Handbook (FAA-H-8083-2A); 14 CFR; Commercial Pilot ACS (FAA-S-ACS-7B). Checked against current sources 2026-11-13.