The regulatory question raised in this forum post — which legs of a multi-stop flight a commercial pilot may legally charge for — touches on a persistent gray area in FAA operating rules that trips up newly minted commercial pilots and instructors alike. In the scenario described, a pilot flies from Airport A to Airport B to pick up a passenger, then continues to Airport C. Under Part 61 commercial pilot privileges (assuming the operation doesn't require a Part 119 certificate, such as when the aircraft owner/passenger is providing the airplane and the pilot is being compensated solely for pilot services under the common "provide your own aircraft" exception in 61.113 or similar arrangements), the general FAA position is that compensation may be collected for legs during which the pilot is actually performing pilot services for hire — meaning all three legs in this scenario could potentially be billable, including the positioning leg from A to B, since the pilot is exercising commercial privileges and being paid for piloting duties throughout the flight, not for carrying passengers on a specific segment. This distinction — pay for pilot services versus pay for carriage of persons or property — is central to how the FAA differentiates a legal Part 61 commercial operation from an operation that would require an air carrier certificate.
The second half of the question, involving a private pilot splitting pro rata costs with friends under 61.113(c), is a much more tightly constrained scenario and one of the most commonly misunderstood rules in general aviation. Pro rata cost-sharing requires that the pilot have a "common purpose" with the passengers — meaning the pilot must independently need to be at the destination for reasons unrelated to simply transporting the passenger. If a private pilot flies from A to B purely to pick someone up, with no independent reason to be at B, that leg generally cannot be included in the pro rata cost-sharing calculation, because the flight's sole purpose on that leg is passenger transportation, which fails the common-purpose test the FAA and NTSB have reinforced in enforcement cases going back decades (including the well-known "flight-sharing app" crackdowns like Flytenow). Only the legs where the pilot has a legitimate personal or business reason to travel — coincidentally also carrying the passenger — qualify for pro rata expense-sharing.
For working pilots, CFIs, and check airmen, this distinction matters far beyond checkride trivia. Commercial and ATP applicants are expected to demonstrate command of compensation rules because misapplying them can expose a pilot or operator to violations of 14 CFR 119 (illegal charter operations), which carry certificate action risk and potential civil penalties. Flight schools and DPEs frequently use exactly this kind of "pick up a passenger en route" scenario during oral exams because it forces the applicant to articulate the difference between being paid for piloting (legal under Part 61 commercial privileges in many contexts) and being paid for transporting people or cargo (which triggers Part 135 requirements). Charter operators, fractional programs, and Part 91K flight departments deal with adjacent versions of this issue constantly when structuring owner-flown positioning legs, deadhead segments, and repositioning flights to ensure compensation structures don't inadvertently cross into common carriage.
More broadly, this question reflects the ongoing tension in FAA policy between enabling legitimate cost-sharing and personal flying arrangements and preventing illegal charter — a tension that has intensified with the rise of flight-sharing apps, private jet card programs, and gray-market "shared flight" arrangements marketed on social media. The FAA has issued multiple legal interpretations (Haberkorn, Mangiamele, and others) attempting to clarify pro rata sharing and common-purpose requirements, yet ambiguity persists precisely because scenarios like the one in this post sit at the boundary of the rules. For aspiring commercial pilots, understanding this boundary isn't just a checkride requirement — it's foundational to avoiding enforcement action later in a career that may involve owner-flown aircraft, fractional shares, or informal cost-sharing arrangements with friends and colleagues.