Commercial Oral Exam Prep

A commercial certificate allows you to be compensated for flying. Specifically under 61.133: you can carry persons or property for compensation or hire (with limitations). You can fly for hire as PIC in operations like banner towing, glider towing, aerial photography, pipeline patrol, and similar Part 91 operations. For carrying passengers or cargo for hire, you generally need a Part 119 operating certificate (Part 135).

Under Part 119.1(e), certain operations are exempt from needing an operating certificate: student instruction, certain nonstop sightseeing flights within 25 SM, ferry flights, aerial work (crop dusting, banner towing, aerial photography, pipeline patrol, survey), and others listed in the regulation. Know these exceptions well.

A constant-speed propeller uses a governor to automatically adjust blade pitch to maintain a selected RPM. When the pilot sets an RPM with the propeller lever, the governor adjusts oil pressure to change blade angle — increasing pitch when RPM is too high (speeding condition) and decreasing pitch when RPM is too low (underspeed condition). This keeps RPM constant while allowing the pilot to control power with the throttle (manifold pressure).

Vmc is the minimum control speed with the critical engine inoperative. Below Vmc, you cannot maintain directional control. Factors that increase Vmc (make it more dangerous): aft CG, max takeoff power on the operating engine, low altitude/high density altitude, flaps up, gear up, and bank toward the dead engine. The mnemonic SMACFUM helps remember the conditions under which Vmc is determined.

Per 91.211: Flight crew must use supplemental oxygen above 12,500 feet MSL cabin altitude for more than 30 minutes, and at all times above 14,000 feet MSL. Passengers must be provided oxygen above 15,000 feet MSL cabin altitude.

A microburst is a localized, intense downdraft that spreads outward on contact with the ground. An aircraft flying through a microburst first encounters a headwind (increased performance), then a strong downdraft and tailwind (severe performance loss). This can cause a loss of 50+ knots of airspeed within seconds. Microbursts last 5-15 minutes and can produce winds up to 45 knots. They are associated with convective activity and can occur with or without precipitation.

Start with the aircraft basic empty weight and moment from the POH. Add each item (fuel, pilot, passengers, baggage) multiplied by its arm to get individual moments. Sum all weights (must not exceed max gross weight) and sum all moments. Divide total moment by total weight to get the CG. Verify the CG falls within the approved envelope for the aircraft. Repeat for landing weight (subtract fuel burn).

High-performance: an aircraft with an engine of more than 200 horsepower. Requires a one-time endorsement per 61.31(f). Complex: an aircraft with retractable landing gear, flaps, and a controllable-pitch propeller (for airplanes). Requires a one-time endorsement per 61.31(e). An aircraft can be both.