What Is FAR Part 91? The Rulebook Every Private Pilot Flies By

FAR Part 91 is the section of the Federal Aviation Regulations (14 CFR Part 91) that sets the general operating and flight rules for nearly every civil aircraft flown in the United States. It covers right-of-way, minimum altitudes, fuel reserves, preflight planning, required equipment, and pilot responsibility — the everyday rules you, as a private pilot, fly under.

If you’ve ever heard an instructor say “that’s a Part 91 operation” and nodded like you understood, this one’s for you. When you rent from the club, fly your own airplane, or take the family up for a $100 hamburger, you’re operating under Part 91. Learn it well now, and the rest of your training starts to click.

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What does FAR Part 91 actually cover?

FAR Part 91, formally 14 CFR Part 91, is titled “General Operating and Flight Rules.” It governs how you operate a civil aircraft in U.S. airspace when you are not flying for hire under a more demanding set of rules. For private pilots, Part 91 is the rulebook you live under on essentially every flight.

Think of Part 91 as the “house rules” of flying. It does not teach you to land in a crosswind. It tells you the things you must do and must not do: how low you can fly, how much fuel to carry, who has the right of way, what paperwork lives in the airplane, and what equipment has to work.

The part is organized into subparts. Subpart B — “Flight Rules” — is the heart of it for student and private pilots, covering VFR, IFR, right-of-way, and minimum altitudes. Subpart C deals with required equipment and instruments, and Subpart E covers the maintenance and inspections you, as an owner or operator, are responsible for.

You will not memorize all of Part 91, and nobody expects you to. What you will do is learn the handful of sections that govern day-to-day flying so well that you can recall them in the cockpit without reaching for the book.

How is Part 91 different from Part 121 and Part 135?

Part 91 covers general, non-commercial operations, while Part 121 governs scheduled airlines and Part 135 governs commuter and on-demand charter. The airlines and charter operators follow stricter rules on crew rest, weather minimums, and maintenance because they carry paying passengers on a schedule. As a private pilot flying yourself and friends, you operate under Part 91.

The simplest way to keep them straight is to ask “who is paying, and for what?” When you rent a Cessna 172 and fly your family to the coast, no one is buying transportation from you — that is Part 91. A regional carrier flying 50 passengers on a published schedule is Part 121. Charter a King Air for a single trip, and the operator is flying you under Part 135.

Here is the important nuance: the higher parts build on top of Part 91, they do not erase it. An airline captain still follows Part 91 right-of-way and basic flight rules — Part 121 just adds more. So the time you invest in Part 91 now pays off no matter how far your aviation career goes.

Who is responsible under Part 91?

Under 14 CFR § 91.3, the pilot in command (PIC) is directly responsible for, and is the final authority as to, the operation of the aircraft. That single sentence is one of the most important in all of aviation. Whatever the airplane does, the PIC owns the outcome — the regulation places that responsibility squarely on you.

This authority cuts both ways. Section 91.3 also lets the PIC deviate from any rule to the extent required to meet an in-flight emergency. If the only safe option happens to break a regulation, you are authorized to do what safety demands. The FAA may ask for a written report afterward, but the rule trusts the person in the seat to act.

Responsibility reaches beyond the flight itself. Under 14 CFR § 91.7, no person may operate an aircraft that is not in an airworthy condition, and the PIC is responsible for determining the aircraft is safe before and during flight. Owner and operator duties — keeping inspections current and the aircraft maintained — live in Subpart E and in 14 CFR § 91.403.

When your examiner asks “who is responsible for this airplane today?” the answer is always you. Internalize that early. It changes how you preflight, how you plan, and how you decide when the weather looks marginal.

What are the Part 91 right-of-way rules?

The right-of-way rules in 14 CFR § 91.113 tell you which aircraft must give way when two aircraft are close enough that a collision is possible. The core principle: when aircraft of the same category are converging at roughly the same altitude, the aircraft to the other’s right has the right of way. And an aircraft in distress always has the right of way over all other air traffic.

Before any of the specific rules apply, 14 CFR § 91.113(b) sets the master rule: regardless of who has the right of way, every pilot must remain vigilant to see and avoid other aircraft. The regulations never excuse you from looking outside.

A few situations come up constantly, so commit them to memory:

• Converging (same category): the aircraft on the right has the right of way.
• Head-on: both aircraft give way to the right.
• Overtaking: the aircraft being overtaken has the right of way; the faster aircraft passes well clear on the right.
• Approaching to land: the aircraft on final approach, or the lower of two aircraft on final, generally has the right of way — but you cannot cut in front of or overtake another aircraft on final.

There is also a category order when different types converge. Less maneuverable aircraft have priority: a balloon outranks a glider, a glider outranks an airship, and powered aircraft give way to balloons, gliders, and airships. The logic is simple — the aircraft with the fewest options gets to keep going.

What minimum altitudes does Part 91 require?

Under 14 CFR § 91.119, you must fly high enough that, if your engine fails, you can make an emergency landing without undue hazard to people or property on the surface. Over congested areas like a city or open-air assembly, the rule requires at least 1,000 feet above the highest obstacle within a 2,000-foot horizontal radius. Over other than congested areas, the minimum is generally 500 feet above the surface.

One allowance surprises new pilots. Over open water or sparsely populated areas, you may fly lower than 500 feet, but you must stay at least 500 feet away from any person, vessel, vehicle, or structure. That is a horizontal distance, not an altitude floor, and it is how legal low flying works in remote country. These minimums do not apply when you are taking off or landing. The rule governs cruise and maneuvering flight.

The whole section comes back to one idea: altitude is your friend. The minimums exist so an engine failure does not become a tragedy on the ground. When I teach this, I tell students to think less about “what’s the lowest I’m allowed” and more about “how much glide range am I giving myself right now?”

If you want this kind of rule explained the way it actually matters in the cockpit — not just memorized for a test — that is exactly how we build the lessons in our Private Pilot Ground School. Every regulation is tied back to a real decision you will make as pilot in command.

What does Part 91 require before every flight?

Under 14 CFR § 91.103, before beginning a flight, the pilot in command must become familiar with all available information concerning that flight. For any flight away from the local area, that specifically includes weather reports and forecasts, fuel requirements, alternatives if the planned flight cannot be completed, and any known traffic delays. For flights not in the vicinity of an airport, it also includes runway lengths and takeoff and landing distance data.

This is the regulation behind the “WKRAFT” memory aid your instructor may use — Weather, Known ATC delays, Runway lengths, Alternatives, Fuel, Takeoff/landing distances. The point is not the acronym. The point is the law expects you to plan, not to launch and hope.

Notice how it ties back to PIC responsibility. The FAA does not require an instructor or dispatcher to gather this for you — under Part 91, gathering “all available information” is on the pilot in command. Day one as a certificated pilot, this is the habit that keeps you safe: a real briefing, a real fuel plan with reserves, and a real answer to “what will I do if I can’t land where I planned?”

The day the rule saved me a 40-mile detour

A few summers back I was flying a Cessna 172 out of a small strip in interior Alaska, heading to a friend’s cabin with a passenger and a load of supplies. The weather was VFR but soft — a broken layer building over the ridges between us and the destination. On the ground, I did the thing § 91.103 actually asks for: I looked at all available information, not just the part I wanted to see.

The fuel math was fine for the direct route. The “alternatives” piece is where it got interesting. If that layer dropped and the pass closed, my direct line had nowhere good to go — just rising terrain and trees. So before I turned the key, I picked a longer valley route that stayed over a river the whole way, with two gravel bars I could put the 172 down on if I had to.

Twenty minutes in, the pass did exactly what I worried it would and socked in. Because I had already flown the “what if I can’t complete this as planned” question on the ground, the decision in the air was boring — I just followed the valley I’d picked. We landed maybe forty minutes late, engine never missing a beat, my passenger never knowing there’d been a decision to make.

That is what Part 91 is really for. Section 91.103 reads like dry paperwork on the page. In the airplane, it is the difference between a calm rerouting and a bad day.

PLT Study Guide

The FAA tags airman knowledge test questions with PLT (Pilot Learning Statement) codes. Several map directly to the Part 91 topics in this article. Here are the ones that matter, in plain English.

A study tip: when a written-exam question quotes a Part 91 section number, do not panic about the number. Read what the situation is asking — converging traffic, low altitude, preflight planning — and the right-of-way, altitude, or preflight logic above will get you to the answer.

Frequently Asked Questions

Part 91 can feel like a wall of section numbers when you first open the FAR/AIM. It is not. It is a small set of common-sense rules written by people who learned them the hard way — fly high enough to glide clear, carry more fuel than the leg needs, yield to the airplane on your right, and know before you go. Learn those, and you are flying like a pilot in command, not just a certificate holder.

FROM CHRIS

If you are just starting out and want a clear, jargon-free path through the regulations and everything else on the private pilot syllabus, that is exactly what we built Angle of Attack for. Aviation education since 2006, and we have helped thousands of students go from “what is Part 91?” to confident pilot in command.

Throttle On!

Chris Palmer

Founder & Chief CFI, Angle of Attack — Two-Time Master Aviation Educator and Gold Seal CFI