If you're staring down the Private Pilot Airman Knowledge Test (the "written"), you already know the FAR/AIM section is where good scores go to die. The aerodynamics and weather questions are mostly pattern-matching. The regulations questions are where examiners — and the FAA test bank — set traps.
We pulled the question categories that show up most often in failed-question reviews from instructors, DPEs, and our own GroundScholar mock-test data. Five FARs account for a wildly disproportionate share of missed regulation questions: 91.103, 91.151, 91.155, 91.205, and 61.113. Below is exactly what the test bank loves to ask, why students miss it, and how to stop missing it.
Why students fail the FAR section
The Private Pilot written has 60 questions and you need a 70% to pass. That means you can miss 18. Sounds generous — until you realize the FAA tends to cluster regulation questions, and a single confused concept (say, fuel reserves) can cost you 3-4 questions in a row.
The failures we see most aren't from students who didn't study. They're from students who:
- Memorized the wrong number. (Day VFR fuel reserve is 30 minutes, not 45.)
- Confused day vs. night requirements. Equipment, fuel, and currency all change after sunset.
- Skipped the airspace fine print. Class E above 10,000 ft MSL has different VFR minimums than Class E below.
- Treated 91.103 as common sense. It's not — the FAA wants specific elements.
Let's go through them.
1. FAR 91.103 — Preflight Action
FAR 91.103 is one of the single most-tested regulations on the PPL written, and the trap is simple: the FAA wants you to know that for any flight, the PIC must become familiar with all available information concerning that flight. For flights not in the vicinity of an airport, and for IFR or any flight, that information specifically includes:
- Runway lengths at airports of intended use
- Takeoff and landing distance data from the AFM/POH
- Weather reports and forecasts
- Fuel requirements
- Alternatives if the planned flight cannot be completed
- Known traffic delays advised by ATC
Why students miss it: The question often phrases it as "Preflight action for a flight not in the vicinity of the departure airport must include…" and the trap answer says only "weather reports and forecasts." The correct answer is the longer list — typically the option that mentions runway lengths and takeoff/landing distance.
Lock it in: When you see "91.103," think WKRAFT: Weather, Known traffic delays, Runway lengths, Alternatives, Fuel, Takeoff/landing distance.
2. FAR 91.151 — Fuel Requirements for VFR
If there's one regulation that wrecks more knowledge tests than any other, it's FAR 91.151. The numbers are tiny but the question writers love to swap them.
| Condition | Minimum reserve at normal cruise |
|---|---|
| Day VFR | 30 minutes |
| Night VFR | 45 minutes |
That's it. Two numbers. And students miss it constantly because:
- They confuse it with IFR fuel reserves (45 minutes, FAR 91.167) — different rule, different test.
- They forget the reserve is calculated at normal cruise speed, not at idle or best endurance.
- They miss that the rule applies to the first point of intended landing, not destination — relevant when the question describes a flight with multiple legs.
Trap question example: "You're planning a VFR cross-country that will land after sunset. What is the minimum fuel reserve required?" Answer: 45 minutes at normal cruise — because part of the flight occurs at night.
3. FAR 91.155 — Basic VFR Weather Minimums
FAR 91.155 is the hardest single regulation on the test for most students because it's a memorization grid. The FAA will test the corners of this table.
| Airspace | Flight Visibility | Distance from Clouds |
|---|---|---|
| Class B | 3 SM | Clear of clouds |
| Class C, D, E (below 10,000 MSL) | 3 SM | 500 below, 1,000 above, 2,000 horizontal |
| Class E at or above 10,000 MSL | 5 SM | 1,000 below, 1,000 above, 1 SM horizontal |
| Class G ≤ 1,200 AGL (day) | 1 SM | Clear of clouds |
| Class G ≤ 1,200 AGL (night) | 3 SM | 500/1,000/2,000 |
| Class G > 1,200 AGL & ≤ 10,000 MSL (day) | 1 SM | 500/1,000/2,000 |
| Class G > 1,200 AGL & ≤ 10,000 MSL (night) | 3 SM | 500/1,000/2,000 |
| Class G > 10,000 MSL | 5 SM | 1,000/1,000/1 SM |
Why students miss it: The most common failed questions involve Class G at night, Class E above 10,000 MSL, and the special VFR carve-outs. A surprising number of test-takers also miss the trick that Class B is just "clear of clouds" — they over-apply the 500/1,000/2,000 rule everywhere.
Memorization shortcut: "3-152" for normal Class E (3 SM, 1,000 above, 500 below, 2,000 horizontal). Then learn the two exceptions: B = clear of clouds, 3 SM and above 10,000 = 5-1-1-1.
4. FAR 91.205 — Required Equipment
FAR 91.205 is the equipment list, and the FAA loves to ask which instruments must be installed and operative for day VFR, night VFR, and IFR. The mnemonic that's been saving PPL applicants for decades:
Day VFR — "A TOMATO FLAMES":
- Airspeed indicator
- Tachometer (each engine)
- Oil pressure gauge (each engine using pressure system)
- Manifold pressure (each altered engine)
- Altimeter
- Temperature gauge (each liquid-cooled engine)
- Oil temperature gauge (each air-cooled engine)
- Fuel gauge (each tank)
- Landing gear position indicator (if retractable)
- Anti-collision lights (for aircraft certificated after 3/11/96)
- Magnetic compass
- ELT (when required by FAR 91.207)
- Safety belts and shoulder harnesses
Night VFR adds — "FLAPS":
- Fuses (one spare set, or three of each kind)
- Landing light (if for hire)
- Anti-collision lights
- Position lights
- Source of electrical power
Why students miss it: They confuse "anti-collision" (required day VFR for newer aircraft, always required at night) with "position lights" (night only). They also forget that a landing light is only required when the aircraft is operated for hire — not for every night flight.
5. FAR 61.113 — Privileges and Limitations of a Private Pilot
Not on your key-FAR list, but worth flagging: this one shows up on nearly every PPL written. The trap is expense sharing. A private pilot may not act as PIC for compensation or hire, but may share operating expenses with passengers pro-rata — and only for fuel, oil, airport expenditures, or rental fees. If the question describes splitting "all costs" or "hangar fees," it's wrong. The pilot must also pay at least a pro-rata share — they cannot fly for free while passengers cover the bill.
Other FARs the test bank loves
A shorter list of regulations you should know cold:
- FAR 61.56 — Flight review every 24 calendar months (1 hour ground + 1 hour flight).
- FAR 61.57 — Recency of experience: 3 takeoffs/landings in 90 days to carry passengers; full stop landings required at night and in tailwheel aircraft.
- FAR 91.3 — PIC is the final authority and may deviate from any rule in an in-flight emergency.
- FAR 91.107 — Seatbelts and shoulder harnesses for taxi, takeoff, and landing.
- FAR 91.111 / 91.113 — Right-of-way rules (balloon → glider → airship → airplane/rotorcraft, and aircraft in distress always wins).
- FAR 91.159 — VFR cruising altitudes above 3,000 AGL (odd+500 eastbound, even+500 westbound).
- FAR 91.211 — Supplemental oxygen (12,500-14,000 MSL after 30 min; required above 14,000 for crew; passengers above 15,000).
- FAR 91.215 — Transponder requirements (Mode C above 10,000 MSL excluding ≤ 2,500 AGL, and within Mode C veil).
How to stop missing FAR questions
- Study the FAR text directly, not paraphrases. Most prep apps summarize. The FAA writes test questions using language pulled almost verbatim from the regulations.
- Drill the numbers in isolation. Build flashcards for just the numerical thresholds: 30/45 fuel, 3-152 VFR mins, 12,500/14,000/15,000 oxygen, 10,000 transponder.
- Practice corner-case questions. Class G at night, Class E above 10,000, equipment for night vs. day, expense sharing edge cases. The test bank lives in the corners.
- Take full-length timed practice tests. Then review every wrong answer with the actual FAR open. If you can't recite the cite, you don't know the rule.
How GroundScholar helps with this
GroundScholar's Private Pilot drill mode tracks which FARs you miss most and re-surfaces those questions until you're hitting 90%+ consistently. Every answer explanation links to the actual regulation text — not a paraphrase — so you're learning from the source the FAA writes questions from. The mock written test pulls from the same question style as the real FAA bank, weighted toward the high-failure categories above.
For the oral and checkride later, the AI examiner uses the same FAR-anchored knowledge graph: when you say "45 minutes night reserve," it knows you're citing FAR 91.151(a)(2) and can drill deeper if your answer was shaky. Every cite is verified against the live FAR/AIM, so you're never memorizing outdated numbers.
If you've already failed the written once — or you're three weeks out and your practice scores are stuck at 72% — start with the FARs above. They're where the points are hiding.