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Are you preparing for your FAA knowledge tests?

This post breaks down the top 10 most common codes for each major knowledge test from January 1 through May 1, 2026. The data is from www.FAATestCodeLookup.com where there have been thousands of reports entered that help CFIs and applicants reference the codes that showed up as missed on their respective knowledge tests.

Understanding these high-frequency missed topic areas can help prioritize your study time effectively and boost your chances of passing on the first try.

Below are the codes that are showing up regularly and the associated content description from the ACS or each test.

Private Pilot Tests:

PA.IV.C.K4 – Ground effect.
PA.II.B.K1 – Passenger briefing requirements, including operation and required use of safety re
PA.I.G.K1c – Powerplant and propeller
PA.IX.A.K2 – Immediate action items and emergency procedures.
PA.I.C.K2 – Acceptable weather products and resources required for preflight planning, current
PA.VI.A.K5 – Plotting a course, including
PA.IV.F.K3 – Wind correction techniques on approach and landing.
PA.II.D.K3 – Airport markings, signs, and lights.
PA.I.E.K1 – Airspace classes and associated requirements and limitations.
PA.I.F.K1 – Elements related to performance and limitations by explaining the use of charts, ta

Instrument Rating Tests:

IR.II.B.K1d – Magnetic compass.
IR.I.B.K3e – Frost.
IR.I.C.K1e – Enroute charts.
IR.I.C.K3c – Fuel requirements, including reserve.
IR.I.C.K1d – Primary and alternate airports.
IR.I.B.K3a – Adverse weather phenomena, including wind shear, and their effect on airplane control and performance.
IR.I.B.K3f – Clouds.
IR.II.B.K2a – Differences between magnetic heading/course and true heading/course.
IR.I.B.K2a – Airport observations (METAR and SPECI) and pilot weather reports (PIREP).
IR.I.B.K3h – Thunderstorms and microbursts.

Commercial Pilot Tests:

CA.I.F.K1 – Elements related to performance and limitations by explaining the use of charts, tables, and data to determine performance.
CA.I.F.K3 – Aerodynamics.
CA.I.G.K1c – Powerplant and propeller.
CA.IV.E.K2 – Best angle of climb speed (VX) and best rate of climb speed (VY).
CA.I.A.K2 – Privileges and limitations of a commercial pilot certificate.
CA.I.E.K1 – Airspace classes and associated requirements and limitations.
CA.VII.E.K2 – Situations that could lead to an inadvertent spin.
CA.IV.B.K1 – A stabilized approach, including energy management concepts.
CA.VI.B.K4 – Use of ATC radar services.
CA.VIII.B.K1 – Operation of pressurization systems.

Flight Instructor Tests:

AI.III.A.K1 – Certification, currency, and recordkeeping requirements, including training and logbook entries.
AI.II.J.K1 – 14 CFR parts 1, 61, and 91.
AI.II.K.K2 – Required student pilot pre-solo knowledge test, solo endorsements, and logbook entries.
AI.II.G.K1 – Airspace classes and associated requirements and limitations.
AI.III.C.K3 – Meteorology applicable to the departure, en route, alternate, and destination under visual flight
AI.II.F.R6 – Shifting, adding, and removing weight.
AI.II.D.K4 – Forces acting on an airplane.
AI.II.D.K2 – Airplane stability, maneuverability and controllability.
AI.II.I.K5 – Calculating
AI.III.A.K2 – Privileges and limitations of pilot certificates and ratings at student pilot, sport, recreational, private

FI.I.D.K2 – Traditional assessments.
FI.I.B.K3 – Perceptions and insight.
FI.I.C.K10c – Lesson plans
FI.I.C.K5c – Guided discussion
FI.I.B.K6a – Cognitive
FI.I.C.K4 – Organization of material.
FI.I.A.K2d – Physical discomfort, illness, fatigue, and dehydration
FI.I.A.K1e – Defense mechanisms
FI.I.A.K2b – Impatience
FI.I.C.K2 – Course of training.

The FAA has issued InFO 26006 (April 10, 2026) to address questions following the MOSAIC rule, which expanded sport pilot aircraft privileges effective October 22, 2025.

Flight instructors with only a sport pilot rating (14 CFR Part 61 Subpart K) are limited to providing training, checking, and endorsements solely for sport pilot privileges under Subpart J. The same restriction applies to Subpart H instructors when they exercise sport pilot privileges.

Any endorsements issued—including flight reviews, high-performance, complex, or tailwheel endorsements—restrict the recipient to sport pilot limitations (§ 61.315 and 61.316), even if the pilot holds a higher certificate.

A sport pilot only flight instructor who provides flight training, including a flight review, even to the holder of a higher-level certificate, is only allowed to provide training that would allow the recipient of that training to exercise sport pilot privileges. To highlight this point in an example consider the following:

• A private pilot has an expired medical, but is flying exercising “sport pilot privileges.”
• That private pilot receives a flight review from a Sport Pilot (only) CFI.
• That private pilot is limited to flying only under sport pilot privileges, even if they then get a new third-class or higher medical or meet the requirements of BasicMed.

For Sport pilot CFIs who are providing a flight review, to make this more clear, the FAA recommends using this sample language for flight reviews (and similar wording for other endorsements) to clearly state the limitation:

“I certify that [name], [certificate grade/number], has satisfactorily completed a flight review of 14 CFR § 61.56(a) on [date] and is limited to sport pilot privileges and limitations (Subpart J).”

Flight training providers and instructors are encouraged to review the full InFO and incorporate the clarified endorsement language to avoid inadvertent privilege limitations. This guidance will be added to future updates of AC 61-65 and AC 61-146.

You can find this document by clicking here.