Most-missed private pilot written test questions (from 8,049 real answers)

What the data says

• Steep Turns is the most-missed ACS task: 42% of learner-question pairs had at least one wrong answer (119 pairs). It is where load factor, maneuvering speed, adverse yaw and skids live. Its ACS area carries 3% of the test, so it costs fewer points than its miss rate suggests; the same physics also shows up in other areas.
• Operation of Systems is the biggest trap by volume: learners practiced it the most (727 learner-question pairs) and still missed it 20% of the time.
• Light-gun signals: 3 of the 25 most-missed questions are tower light signals. Steady versus flashing, ground versus air: a 3-row table that costs points every time.
• The single most-missed question (9 of 11 learners got it wrong at least once): “Wash-out refers to a wing design where” The answer: the angle of incidence decreases from root to tip. See why.

Miss rate by ACS area

A second, bigger sample: our free PPL test

Anyone can take the free 5-question PPL test, drawn from a set of hard questions. It logs only the topic and whether the answer was right, so it cannot rank questions, but it adds 3,583 anonymous answers (June 28, 2026 to October 3, 2026, bots and test traffic removed). There, Airspace & VFR Minimums is missed most, 54% of the time.

The 25 most-missed questions

1. #1Performance and LimitationsPA.I.F.K3

   82% missed it: 9 of 11 learners got it wrong at least once (15 answers in total)

   Wash-out refers to a wing design where

   • AThe wing thickness decreases from root to tip
   • BThe wing chord decreases from root to tip
   • CThe angle of incidence increases from root to tip
   • The angle of incidence decreases from root to tipCorrect

   Why it traps people

   Taper (chord shrinking toward the tip) and thinner tips are real wing features, so they sound right. Washout is twist: the angle of incidence decreases from root to tip, so the root stalls first and the ailerons keep working.

   The answer, explained

   Wash-out causes the root to stall before the tip, maintaining aileron effectiveness during a stall.

   Source: FAA-H-8083-25 Pilot's Handbook of Aeronautical Knowledge, Aerodynamics of Flight · Question written by Rotate Pilot

2. #2Performance and LimitationsPA.I.F.K3

   70% missed it: 7 of 10 learners got it wrong at least once (16 answers in total)

   What causes an airplane to turn?

   • AThe vertical component of lift
   • BThe side force created by the rudder
   • The horizontal component of liftCorrect
   • DThe centrifugal force in the turn

   Why it traps people

   The rudder yaws the nose, so it feels like the thing that turns the airplane. It is the bank: tilting the lift vector gives it a horizontal component that pulls the airplane around the turn. The rudder only keeps the turn coordinated.

   The answer, explained

   When an airplane is banked, the lift vector tilts. Its horizontal component pulls the airplane toward the center of the turn.

   Source: FAA-H-8083-25 PHAK, Forces in Turns · Question written by Rotate Pilot

3. #3Communications, Light Signals, and Runway Lighting SystemsPA.III.A.K3

   70% missed it: 7 of 10 learners got it wrong at least once (15 answers in total)

   A flashing red light from the tower to an aircraft on the ground means

   • Taxi clear of the runway in useCorrect
   • BStop
   • CReturn to starting point on the airport
   • DCleared for takeoff

   Why it traps people

   Red means stop, so "Stop" gets picked, but that is STEADY red. FLASHING red to an aircraft on the ground means taxi clear of the runway in use. To an aircraft in flight, flashing red means airport unsafe, do not land.

   The answer, explained

   A flashing red light gun signal to an aircraft on the ground means taxi clear of the runway in use (AIM 4-3-13). Don't confuse it with STEADY red (stop) or flashing red to an aircraft in flight (airport unsafe, do not land). Memorize by mode: on the ground = clear the runway; in flight = do not land.

   Source: AIM 4-3-13 (Traffic Control Light Signals); 14 CFR 91.125 · Question written by Rotate Pilot

4. #4Performance and LimitationsPA.I.F.K2e

   70% missed it: 7 of 10 learners got it wrong at least once (19 answers in total)

   A forward center of gravity affects stall speed by

   • AOnly affecting stall speed at high altitude
   • BHaving no effect on stall speed
   • Increasing stall speedCorrect
   • DDecreasing stall speed

   Why it traps people

   Forward CG makes the airplane more stable, and stable sounds like slower stalls. But a forward CG needs more tail-down force to balance, so the wing carries extra load and stalls at a higher speed. Aft CG lowers stall speed but erodes stability.

   The answer, explained

   A forward CG increases stall speed. The CG ahead of the lift point creates a nose-down moment, so the tail must produce more downforce; the wing then carries more than just aircraft weight, raising effective wing loading and thus the speed at which it stalls. The tempting 'decreases' answer reverses the logic, aft CG lowers stall speed (but hurts stability).

   Source: FAA-H-8083-25 PHAK, Weight and Balance (effects of CG) · Question written by Rotate Pilot

5. #5Steep TurnsPA.V.A.K2a

   67% missed it: 8 of 12 learners got it wrong at least once (15 answers in total)

   Adverse yaw is corrected by applying

   • ABack pressure in the direction of the roll
   • BRudder opposite the direction of the turn
   • CAileron opposite the direction of the turn
   • Rudder in the direction of the turnCorrect

   Why it traps people

   Adverse yaw pulls the nose away from the turn, and "opposite" sounds like a correction. The down aileron on the rising wing makes more drag; you cancel it with rudder in the same direction as the turn (step on the ball).

   The answer, explained

   Adverse yaw — the nose swinging toward the outside of a turn as you roll in — is caused by the down-aileron wing producing more drag. You correct it with coordinated rudder in the DIRECTION of the turn (step on the ball). 'Opposite rudder' is the trap; that would worsen the yaw. Smooth, simultaneous rudder-with-aileron keeps the turn coordinated.

   Source: FAA-H-8083-25 PHAK, Flight Controls (adverse yaw) · Question written by Rotate Pilot

6. #6Performance and LimitationsPA.I.F.K3

   62% missed it: 8 of 13 learners got it wrong at least once (19 answers in total)

   A wing with a high aspect ratio will have

   • AMore induced drag for a given lift coefficient
   • Less induced drag for a given lift coefficientCorrect
   • CLess parasite drag at a given angle of attack
   • DA higher stall speed for a given wing loading

   Why it traps people

   A bigger, longer wing sounds like more drag. For the same lift coefficient a long, slender wing makes weaker wingtip vortices, so it has LESS induced drag. That is why gliders look the way they do.

   The answer, explained

   A high-aspect-ratio wing (long and slender) produces less induced drag for a given lift coefficient because the wingtip vortices are proportionally smaller and weaker. That's why gliders have long, thin wings. The trap is 'more induced drag.' The trade-off is structural: high-aspect-ratio wings are harder to build strong and can be less maneuverable.

   Source: FAA-H-8083-25 PHAK, Aerodynamics of Flight (aspect ratio) · Question written by Rotate Pilot

7. #7Pilotage and Dead ReckoningPA.VI.A.K5a

   64% missed it: 7 of 11 learners got it wrong at least once (20 answers in total)

   The agonic line is where

   • ACompass deviation is zero — the magnetic compass reads exactly the same as the heading indicator
   • BMagnetic dip is zero — the compass card remains level throughout turns and airspeed changes
   • CMagnetic variation is greatest — true north and magnetic north differ by the largest amount
   • Magnetic variation is zero — true north and magnetic north are alignedCorrect

   Why it traps people

   Variation and deviation are easy to swap. Variation is the Earth's: the angle between true and magnetic north, and on the agonic line it is zero. Deviation is your airplane's: the error its own magnetic fields put into the compass.

   The answer, explained

   Along the agonic line, true north and magnetic north are the same, so variation is 0°.

   Source: FAA-H-8083-25 PHAK, Navigation · Question written by Rotate Pilot

8. #8Navigation Systems and Radar ServicesPA.VI.B.K1

   64% missed it: 7 of 11 learners got it wrong at least once (24 answers in total)

   ADF (Automatic Direction Finder) points toward

   • AThe DME (Distance Measuring Equipment) site
   • The NDB (Non-Directional Beacon) stationCorrect
   • CThe VOR (VHF Omnidirectional Range) station
   • DThe magnetic north pole at all times

   Why it traps people

   VOR is the navaid everyone learns first, so it absorbs the answer. The ADF needle points to the NDB it is tuned to, showing relative bearing; magnetic heading plus relative bearing gives the magnetic bearing to the station.

   The answer, explained

   An ADF needle always points directly at the NDB (Non-Directional Beacon) it's tuned to, showing relative bearing from the nose. It does NOT point to true north, a VOR, or an airport. Because it shows bearing relative to the aircraft's heading, you must add the magnetic heading to the relative bearing to get the magnetic bearing TO the station.

   Source: FAA-H-8083-25 PHAK, Navigation (ADF/NDB); AIM 1-1-2 · Question written by Rotate Pilot

9. #9Performance and LimitationsPA.I.F.K1

   64% missed it: 7 of 11 learners got it wrong at least once (21 answers in total)

   Service ceiling is defined as

   • AThe altitude where the airplane can maintain only 500 FPM rate of climb
   • BThe highest altitude at which the airplane may legally be operated
   • The altitude where the airplane can maintain only 100 FPM rate of climbCorrect
   • DThe altitude where the airplane can no longer maintain any rate of climb

   Why it traps people

   Two ceilings, two numbers. Service ceiling is where the airplane can still climb at 100 fpm; absolute ceiling is where it cannot climb at all. The 500 fpm option is invented.

   The answer, explained

   Service ceiling: the altitude at which the maximum rate of climb is 100 FPM. Absolute ceiling: zero rate of climb.

   Source: FAA-H-8083-25 PHAK, Aircraft Performance · Question written by Rotate Pilot

10. #10Operation of SystemsPA.I.G.K1h

    58% missed it: 7 of 12 learners got it wrong at least once (21 answers in total)

    Flying from warm air into colder air without adjusting the altimeter causes it to

    • AShow pressure altitude instead
    • Read higher than actual altitudeCorrect
    • CIndicate true altitude accurately
    • DRead lower than the actual altitude

    Why it traps people

    Colder air feels like it should make the altimeter read low. Cold air is denser, so the pressure levels sit lower and the altimeter reads HIGHER than your true altitude. "From hot to cold, look out below."

    The answer, explained

    'Warm to cold, look out below.' Colder, denser air means true altitude is lower than what the altimeter shows.

    Source: FAA-H-8083-25 PHAK, Flight Instruments (altimeter errors) · Question written by Rotate Pilot

11. #11Human FactorsPA.I.H.K4

    60% missed it: 6 of 10 learners got it wrong at least once (16 answers in total)

    The DECIDE model for aeronautical decision-making stands for

    • ADetermine, Estimate, Choose, Investigate, Decide, Evaluate
    • BDecide, Execute, Consider, Identify, Document, Evaluate
    • CDetect, Evaluate, Choose, Implement, Document, End
    • Detect, Estimate, Choose, Identify, Do, EvaluateCorrect

    Why it traps people

    Every distractor is a plausible-sounding list of decision verbs. The FAA's DECIDE model is: Detect a change, Estimate the need to react, Choose a desirable outcome, Identify actions, Do the necessary action, Evaluate the effect.

    The answer, explained

    DECIDE: Detect a change, Estimate its significance, Choose a safe outcome, Identify actions, Do the best action, Evaluate the result.

    Source: FAA-H-8083-25 PHAK, Aeronautical Decision-Making · Question written by Rotate Pilot

12. #12Operation of SystemsPA.I.G.K1a

    60% missed it: 6 of 10 learners got it wrong at least once (14 answers in total)

    Anti-servo tabs on a stabilator

    • ABalance the stabilator aerodynamically so control forces remain constant
    • Increase control force feedback so the stabilator is not too sensitiveCorrect
    • CReduce control force feedback so the stabilator is easier to deflect
    • DMove opposite the stabilator to hold the surface in a trimmed position

    Why it traps people

    A tab that "helps" sounds like it should make the controls lighter; that is a servo tab. On a stabilator, the anti-servo tab moves in the same direction as the trailing edge and adds resistance, so the all-moving tail is not too sensitive.

    The answer, explained

    Stabilators (all-moving horizontal tails) can be overly sensitive. Anti-servo tabs provide an opposing force to give the pilot better feel.

    Source: FAA-H-8083-25 PHAK, Flight Controls (stabilator) · Question written by Rotate Pilot

13. #13Weather InformationPA.I.C.K3g

    60% missed it: 6 of 10 learners got it wrong at least once (18 answers in total)

    Clear air turbulence (CAT) is most likely found

    • ANear the jet stream, always on the warm (equatorial) side
    • BBelow 10,000 feet in the friction layer over rough terrain
    • Near the jet stream, especially on the polar (cold) sideCorrect
    • DWithin the mature stage of a well-developed cumulonimbus

    Why it traps people

    Thunderstorms are the obvious turbulence answer, but turbulence inside a storm is not clear-air turbulence. CAT is tied to strong wind shear near the jet stream, most often on its polar (cold, low-pressure) side.

    The answer, explained

    CAT is turbulence in clear air (no clouds) often associated with wind shear near the jet stream. It's hard to detect and forecast.

    Source: FAA-H-8083-28 Aviation Weather Handbook (clear air turbulence) · Question written by Rotate Pilot

14. #14Communications, Light Signals, and Runway Lighting SystemsPA.III.A.K3

    60% missed it: 6 of 10 learners got it wrong at least once (15 answers in total)

    Light signals from the tower — steady green to an aircraft on the ground means

    • AReturn to starting point
    • Cleared for takeoffCorrect
    • CCleared to cross runway
    • DCleared to taxi

    Why it traps people

    On the ground, green means go, but which go? STEADY green is cleared for takeoff; FLASHING green is cleared to taxi.

    The answer, explained

    A steady green light on the ground means cleared for takeoff.

    Source: AIM 4-3-13 (Traffic Control Light Signals) · Question written by Rotate Pilot

15. #15Steep TurnsPA.V.A.K2c

    55% missed it: 6 of 11 learners got it wrong at least once (21 answers in total)

    If aircraft weight decreases, maneuvering speed (Va)

    • AIs not affected by weight
    • DecreasesCorrect
    • CStays the same
    • DIncreases

    Why it traps people

    Lighter feels safer and faster. But a lighter airplane stalls at a lower speed, so at a given speed it can reach a damaging load factor before the wing stalls. To keep the same protection, maneuvering speed goes DOWN as weight goes down.

    The answer, explained

    Va decreases with lower weight because the airplane can reach higher load factors before stalling at a given speed.

    Source: FAA-H-8083-25 PHAK, Aerodynamics of Flight (load factor, VA) · Question written by Rotate Pilot

16. #16Navigation Systems and Radar ServicesPA.VI.B.K1

    55% missed it: 6 of 11 learners got it wrong at least once (26 answers in total)

    DME (Distance Measuring Equipment) displays

    • Slant range distance to the ground station in nautical milesCorrect
    • BMagnetic bearing and groundspeed relative to the VOR station
    • CHorizontal ground distance to the ground station in statute miles
    • DSlant range distance to the ground station in statute miles

    Why it traps people

    People picture a map distance. DME measures the line-of-sight (slant range) distance from the airplane to the station, in nautical miles. Directly over the station it still shows your height.

    The answer, explained

    DME shows slant range (line-of-sight) distance to the station, not ground distance. The difference is significant when close to the station at high altitude.

    Source: AIM 1-1-7 (Distance Measuring Equipment) · Question written by Rotate Pilot

17. #17Steep TurnsPA.V.A.K2a

    55% missed it: 6 of 11 learners got it wrong at least once (20 answers in total)

    A skid is an uncoordinated flight condition where

    • AThe airplane's nose is pointed outside the turn (too little rudder)
    • The airplane's nose is pointed inside the turn (too much rudder)Correct
    • CThe airplane's ball is centered but the wings are overbanking in the turn
    • DThe airplane's bank angle is too steep for the rate of turn selected

    Why it traps people

    Slip and skid get swapped. In a skid there is too much rudder for the bank: the nose points into the turn, the rate of turn is too high, and the ball slides to the OUTSIDE. In a slip it is the reverse.

    The answer, explained

    In a skid, excess rudder causes the nose to point inside the turn, and the ball is displaced to the outside of the turn.

    Source: FAA-H-8083-25 PHAK, Flight Instruments (turn coordinator) · Question written by Rotate Pilot

18. #18Performance and LimitationsPA.I.F.K3

    55% missed it: 6 of 11 learners got it wrong at least once (17 answers in total)

    As airspeed increases, induced drag

    • ARemains constant
    • DecreasesCorrect
    • CIncreases
    • DFirst increases then decreases

    Why it traps people

    Total drag rises with speed, and that bleeds into this answer. Parasite drag increases with airspeed; induced drag DECREASES, because at higher speed the wing needs a lower angle of attack to make the same lift.

    The answer, explained

    Induced drag is inversely proportional to the square of airspeed. At higher speeds, lower AOA means less induced drag.

    Source: FAA-H-8083-25 PHAK, Aerodynamics of Flight (drag) · Question written by Rotate Pilot

19. #19Communications, Light Signals, and Runway Lighting SystemsPA.III.A.K3

    50% missed it: 6 of 12 learners got it wrong at least once (18 answers in total)

    Light signals from the tower — steady red to an aircraft in flight means

    • AExercise extreme caution, runway may be occupied
    • Give way to other aircraft and continue circlingCorrect
    • CAirport unsafe, do not land, divert to alternate
    • DReturn to starting point on the airport surface

    Why it traps people

    Red in the air sounds like "do not land", but that is FLASHING red. STEADY red to an aircraft in flight means give way to other aircraft and continue circling.

    The answer, explained

    A steady red light in flight means give way to other aircraft and continue circling.

    Source: AIM 4-3-13 (Traffic Control Light Signals) · Question written by Rotate Pilot

20. #20Pilotage and Dead ReckoningPA.VI.A.K5

    50% missed it: 5 of 10 learners got it wrong at least once (15 answers in total)

    On a Lambert Conformal Conic projection (sectional chart), a straight line approximates a

    • ALine of equal variation
    • BConstant heading line
    • CRhumb line route
    • Great circle routeCorrect

    Why it traps people

    "Constant heading" and "rhumb line" sound like what a straight line should be, and on a Mercator chart they are. Sectionals use the Lambert conformal conic projection, where a straight line is very close to a great circle.

    The answer, explained

    Lambert conformal conic projections are used for sectional charts; straight lines closely approximate great circle routes.

    Source: FAA-H-8083-25 PHAK, Navigation; FAA Aeronautical Chart User's Guide · Question written by Rotate Pilot

21. #21Performance and LimitationsPA.I.F.K3

    50% missed it: 5 of 10 learners got it wrong at least once (13 answers in total)

    The horizontal stabilizer primarily provides

    • ADynamic spiral stability
    • Lateral (roll) stabilityMost-picked wrong answer (4 of 4 recorded wrong picks)
    • Longitudinal (pitch) stabilityCorrect
    • DDirectional (yaw) stability

    Why it traps people

    Pitch happens AROUND the lateral axis, and that word pulls people to "lateral stability". Stability about the lateral axis is called LONGITUDINAL stability; lateral stability is roll. The horizontal stabilizer provides pitch (longitudinal) stability.

    The answer, explained

    The horizontal stabilizer provides pitch stability around the lateral axis.

    Source: FAA-H-8083-25 PHAK, Aerodynamics of Flight (stability) · Question written by Rotate Pilot

22. #22National Airspace SystemPA.I.E.K1

    50% missed it: 5 of 10 learners got it wrong at least once (15 answers in total)

    The maximum indicated airspeed below 10,000 feet MSL is

    • ANo speed limit
    • B300 knots
    • 250 knotsCorrect
    • D200 knots

    Why it traps people

    200 knots is also in 91.117, which is why it tempts: it is the limit under a Class B shelf and near Class C or D airports at or below 2,500 ft. The general limit below 10,000 ft MSL is 250 knots indicated.

    The answer, explained

    14 CFR 91.117(a): No person may fly faster than 250 KIAS below 10,000 feet MSL.

    Source: 14 CFR 91.117 · Question written by Rotate Pilot

23. #23Lost ProceduresPA.VI.D.K1

    50% missed it: 5 of 10 learners got it wrong at least once (18 answers in total)

    If lost, a pilot should first

    • Climb for better visibility and radio/navigation reception, then orient using known techniquesCorrect
    • BSquawk 7700 immediately and hold present heading until ATC provides radar vectors to an airport
    • CReverse course to the reciprocal heading and fly the elapsed time back to the last known fix
    • DDescend for a closer look at ground landmarks, then match features to the sectional chart

    Why it traps people

    Descending for a closer look feels natural and squawking 7700 feels decisive. The FAA's first step is to climb (weather and traffic permitting): more altitude means you see farther and get better radio, navigation and radar coverage.

    The answer, explained

    Climbing improves visibility, radio range, and GPS/VOR reception. Use '4 C's: Climb, Communicate, Confess (to ATC), Comply.'

    Source: FAA-H-8083-25 PHAK, Navigation (lost procedures) · Question written by Rotate Pilot

24. #24Operation of SystemsPA.I.G.K1h

    50% missed it: 5 of 10 learners got it wrong at least once (20 answers in total)

    Indicated airspeed is corrected for instrument and position error to give

    • Calibrated airspeedCorrect
    • BTrue airspeed
    • CDensity airspeed
    • DEquivalent airspeed

    Why it traps people

    True airspeed is the one people care about, so it gets picked too early. The order is I-C-E-T: indicated, corrected for instrument and position error = calibrated; then compressibility = equivalent; then density = true.

    The answer, explained

    IAS corrected for instrument and position error = CAS (calibrated airspeed). CAS corrected for density = TAS.

    Source: FAA-H-8083-25 PHAK, Flight Instruments (airspeed) · Question written by Rotate Pilot

25. #25Steep TurnsPA.V.A.K2d

    50% missed it: 5 of 10 learners got it wrong at least once (21 answers in total)

    The load factor in a 45-degree bank level turn is approximately

    • A2.00 G
    • 1.41 GCorrect
    • 1.15 GMost-picked wrong answer (3 of 3 recorded wrong picks)
    • D1.73 G

    Why it traps people

    1.15 G is the load factor at 30 degrees of bank, the number most students memorize first. At 45 degrees it is 1 / cos 45° ≈ 1.41 G, and at 60 degrees 2 G.

    The answer, explained

    In a level (constant-altitude) turn, the wings must support the aircraft's weight AND provide the horizontal force that curves the flight path. Load factor = 1 / cos(bank angle). At 45 degrees: 1 / cos(45) = 1 / 0.707 = 1.41 G. This is why steeper level turns raise stall speed: at 1.41 G the wing behaves as if the aircraft weighed 41% more, and stall speed rises by the square root of the load factor (about 19% higher at 45 degrees of bank).

    Source: FAA-H-8083-25 PHAK, Aerodynamics of Flight (load factor) · Question written by Rotate Pilot

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