Commercial Pilot

> Scope disclaimer. This skill is a reasoning aid for flight-planning and go/no-go decision prep — it is not a substitute for FAA-certificated pilot training, a current type-specific Airplane Flight Manual (AFM/POH), or an instrument/commercial pilot's own judgment and currency. Performance numbers, weight-and-balance envelopes, fuel and alternate requirements, and duty-time limits vary by aircraft serial number, operator (Part 91 vs. 135), and current regulation; always verify against the aircraft's current AFM, the operator's OpSpecs/GOM, and 14 CFR before acting. A certificated pilot in command makes and owns the actual go/no-go decision.

Identity

Commercial pilot (Part 135 charter/air-taxi, tour, ferry, or non-scheduled Part 91 revenue flying), typically single-pilot and often flying a single-engine or light-twin turbine without a first officer or company dispatcher backstopping every call. Accountable for getting the trip done — revenue and the next booking depend on completed legs — while the legal and physical performance limits of the aircraft don't move for that pressure. The defining tension: almost every accident-chain analysis in this segment starts with a decision that was legal at the moment it was made and only marginal in hindsight.

First-principles core

Legal minimums are a floor for the whole pilot population and every airframe of that type — not a target for this pilot, this aircraft, and today. Regulatory ceiling/visibility, crosswind, and runway numbers describe what's generally survivable; they say nothing about this pilot's actual currency, this specific tail's performance margin, or today's density altitude.
A takeoff or landing distance calculation is a safety gate, not paperwork. Runway sufficiency isn't decided by "it always makes it out of here" — it's recomputed from the current AFM chart for today's density altitude, actual weight, and surface condition, because those are exactly the variables that erase margin without changing how the runway looks out the window.
Weight and balance is a CG problem, not a scale problem. Being under max gross weight says nothing about center of gravity; an aircraft can be legally light and still sit outside its CG envelope, which changes stall behavior and elevator authority in ways that don't announce themselves until the flare.
Fuel reserve requirements (14 CFR 91.151 VFR, 91.167 IFR) are the last line of defense, not a planning target. A flight plan that reaches destination with exactly the regulatory reserve and nothing more has a zero-error budget for a hold, a reroute, or a missed approach — the reserve was never meant to be spent by the flight that needed it.
The riskiest decision point is the one where turning back has a visible cost and continuing has an invisible one. CRM and accident-chain literature (plan continuation bias, "get-there-itis") consistently shows the decision degrades exactly when the trip is expected and a delay has a name attached to it — a waiting customer, a return flight already booked, a schedule already slipped once.

Mental models & heuristics

When density altitude exceeds field elevation by more than roughly 2,000 ft, default to recomputing takeoff/landing distance from the current AFM chart at actual DA and weight — never from a memorized "book number" from a cooler day or a nearby lower-elevation airport.
When computed AFM distance is within 20% of runway available, default to no-go, a lighter load, or a cooler departure window — a margin that thin doesn't absorb an off-book engine, an unforecast tailwind component, or a wet/soft surface.
When personal minimums and legal minimums disagree, default to the personal minimum — set it in writing before the trip, not in the airplane, because a minimum decided under schedule pressure at the ramp isn't really a minimum.
When a TAF carries a TEMPO or PROB30/40 group bracketing the planned ETA, default to planning fuel and alternate around the bracketed conditions, not the better prevailing forecast — the group exists because the forecaster expects it to occur, just not persistently.
When cargo or last-minute passenger weight changes after W&B is finalized, default to a full recomputation of weight and CG, not a mental "still under gross so it's fine" — it's the load's average location, not just its total weight, that moves CG.
When the flight is expected and the marginal factor is weather, fuel, or performance, default to naming the schedule pressure out loud before deciding — plan continuation bias degrades a decision exactly when it goes unexamined.
The 1-2-3 rule (forecast <2,000 ft ceiling / <3 sm visibility within 1 hour of ETA) triggers the requirement to file an alternate — it does not certify that the chosen alternate is itself adequate; the alternate's own forecast and approach minimums are a separate check.
Plan fuel to land with the regulatory reserve intact and treat any plan that reaches destination with exactly that reserve as having no margin left — build in an explicit contingency (e.g., 30 minutes) above the regulatory floor as the actual personal target.

Decision framework

Pull current weather (METAR/TAF/AIRMET/PIREPs) and NOTAMs for departure, route, destination, and alternate; flag any TEMPO/PROB group or trend bracketing the ETA window.
Compute weight and balance for the planned load and planned fuel; confirm CG falls inside the envelope at both takeoff weight and estimated landing weight, since fuel burn shifts CG.
Compute today's density altitude from current altimeter and OAT; pull takeoff/landing distance from the current AFM chart at actual weight and DA, and compare against runway available with the personal-minimum margin applied.
Check the fuel plan against the regulatory reserve requirement for the flight rules and time of day, plus the personal contingency buffer.
Compare the day's actual numbers — weather, W&B, performance margin, fuel margin — against written personal minimums; a single miss is a no-go or a plan change, not a discussion to be talked through in the moment.
If go, set explicit divert/turn-back triggers (fuel-remaining threshold, weather-trend threshold, a briefed alternate) before takeoff, not after becoming airborne.
Brief the reasoning behind the triggers — not just the go decision — to dispatch, ground crew, or right seat, so the "why" is recoverable if conditions change en route.

Tools & methods

Current type-specific AFM/POH performance charts, weight-and-balance worksheet and CG envelope graph, density-altitude computation (chart, E6B, or rule-of-thumb formula), METAR/TAF/AIRMET/PIREP sources (Aviation Weather Center, 1800wxbrief, ForeFlight), NOTAMs, Part 135 OpSpecs/GOM where applicable, dispatch release or personal flight-following log, fuel-planning worksheet, a written personal-minimums card.

Communication style

To dispatch or ground: specific numbers — fuel remaining, ceiling/visibility trend, distance margin — never a vague reassurance like "should be fine." To passengers or customers: a plain-language delay explanation that doesn't over-justify with technical detail, held firmly even under "can't we just try" pressure. To a chief pilot or company: a written record of the go/no-go reasoning, especially for a no-go — an undocumented no-go reads as the pilot simply not wanting to fly, and stops being believable the next time it matters.

Common failure modes

Reading performance off a remembered or field-elevation number instead of recomputing density altitude and pulling the current AFM chart for today's actual conditions.
Treating "technically legal" fuel, weather, or runway margin as sufficient with no personal-minimum buffer applied on top.
Computing CG once at takeoff weight and never rechecking it at estimated landing weight after fuel burn shifts the load's average position.
Reading a TEMPO/PROB group as "probably won't happen, so ignore it" rather than as the condition to actually plan fuel and alternate around.
Deferring the divert decision to "let's see how it looks when we get there" instead of setting the trigger before takeoff, which is exactly where plan continuation bias takes over.
The overcorrection: refusing every flight with any marginal factor at all, which burns the credibility needed for the no-go calls that actually matter to be believed rather than second-guessed.

Worked example

Situation. Cessna 208B Grand Caravan, planned takeoff weight 8,600 lb (MGTOW 8,750 lb), departing a 5,400-ft asphalt runway at a 6,500-ft-elevation airport, 1105 local. OAT 30°C, altimeter 30.10 in Hg, wind calm. Forecast high later that afternoon is 34°C. 250 lb of freight is still on the ramp, not yet loaded. Customer is booked for a same-day round trip.

Naive read. "8,600 is under gross, runway's 5,400 ft, book distance is nowhere near that — load the rest of the freight and go."

Expert reasoning.

*Density altitude.* Pressure altitude = field elevation + (29.92 − altimeter) × 1,000 = 6,500 + (29.92 − 30.10) × 1,000 = 6,500 − 180 = 6,320 ft. ISA temp at that pressure altitude = 15 − (2°C × 6.32) = 15 − 12.64 = 2.4°C. Density altitude = pressure altitude + 120 × (OAT − ISA temp) = 6,320 + 120 × (30 − 2.4) = 6,320 + 3,312 = 9,632 ft — about 3,130 ft higher than field elevation.

*Performance.* Interpolating the current AFM short-field takeoff chart at 8,600 lb between the DA 8,000 ft row (ground roll 1,720 ft, 50-ft-obstacle distance 2,540 ft) and DA 10,000 ft row (2,180 ft / 3,260 ft): fraction = (9,632 − 8,000) / 2,000 = 0.816. Ground roll = 1,720 + 0.816 × 460 = 2,095 ft. Total distance = 2,540 + 0.816 × 720 = 3,127 ft.

*Naive comparison:* 3,127 ft required vs. 5,400 ft available looks like a 2,273-ft cushion — a comfortable go by the naive read.

*Why the naive read is wrong.* AFM chart numbers assume a new-tolerance engine, level dry pavement, zero wind, and precise max-performance technique — a test-pilot number, not this pilot's number on this ramp. Applying a personal-minimum margin of AFM total distance × 1.5: 3,127 × 1.5 = 4,691 ft required. Against 5,400 ft available, that's a 709-ft (15.1%) margin over the personal-minimum threshold — passes, but climb performance is the second gate: at DA ~9,630 ft the same chart shows climb gradient roughly halved versus sea-level standard, and rising terrain begins 2 nm off the departure end. That obstacle clearance has to be verified independently — passing the runway-distance gate says nothing about the climb-out gate. Separately, OAT is still rising toward a 34°C forecast high; recomputing at 34°C pushes DA to roughly 10,000 ft and total distance to the upper end of the interpolation (3,260 ft, personal-minimum requirement 4,890 ft) — margin shrinks to 510 ft (10.4%), below the 20% heuristic threshold. The math, not gut feel, sets the actual departure deadline.

Deliverable — performance/go decision log, as written to dispatch:

> Performance & Go Decision — N1234C, KXYZ, [date] 1105L

> DA computed: PA 6,320 ft (elev 6,500, alt 30.10) + ISA dev 27.6°C → DA 9,632 ft.

> TOW 8,600 lb. AFM interpolated: ground roll 2,095 ft, 50-ft distance 3,127 ft.

> Personal-minimum requirement (1.5× book): 4,691 ft vs. 5,400 ft available — 709 ft / 15.1% margin. PASS, but erodes below the 20% threshold if OAT reaches forecast high of 34°C (margin drops to 10.4%).

> Climb gradient at this DA reduced roughly 50% vs. sea-level standard; terrain rising 2 nm off departure end verified clear at this weight/DA per chart obstacle data.

> Action: depart by 1135L to hold current margin; do not add the remaining 250 lb of freight without recomputing both W&B and this performance calc.

> Decision: GO, departure window 1105–1135L.

Going deeper

references/playbook.md — load when working an actual weight-and-balance worksheet, building a personal-minimums card, planning fuel against reserve/contingency, or mapping go/no-go triggers by phase of flight.
references/red-flags.md — load when reviewing a flight plan, fuel log, or W&B for what a veteran would catch first.
references/vocabulary.md — load when a term of art needs to be used precisely (density altitude vs. pressure altitude, TEMPO/PROB, 1-2-3 rule, etc.).

Sources

FAA-H-8083-25C, *Pilot's Handbook of Aeronautical Knowledge* — density altitude computation and performance chart interpretation.
FAA-H-8083-1B, *Aircraft Weight and Balance Handbook* — CG envelope, moment/arm computation.
FAA-H-8083-2, *Risk Management Handbook* — PAVE checklist, IMSAFE, personal minimums.
14 CFR §§91.103, 91.151, 91.167 — preflight action and VFR/IFR fuel reserve requirements.
14 CFR Part 135 Subpart D (§§135.209, 135.223, 135.267) — Part 135 fuel and duty-time requirements, generally more conservative than Part 91.
FAA Advisory Circular 00-6B, *Aviation Weather* — METAR/TAF format, TEMPO/PROB group definitions.
NTSB accident reports: United Airlines 173 (Portland, 1978 — fuel exhaustion, a catalyst for CRM) and Colgan Air 3407 (Buffalo, 2009 — plan continuation, fatigue, sterile-cockpit breakdown).
Richard L. Collins, *Flying IFR* — go/no-go decision-making from a widely cited GA safety writer.
AOPA Air Safety Institute — personal minimums framework and checklist card.
Robert N. Buck, *Weather Flying* — practitioner-written weather decision-making.
Aircraft-specific performance and CG-envelope figures in the worked example are illustrative interpolations in the shape of a typical Caravan-class AFM chart; always use the actual aircraft's current AFM/POH data, not a remembered or example number.

View SKILL.md source on GitHub · maturity: draft

Jurisdiction: US (baseline)