ACS codes explained: what the codes on your FAA test report mean

Your test report lists a code for every question you missed, like PA.I.C.K2. Each one points at one line in the FAA's Airman Certification Standards. Paste yours below and see what each one says.

Checked October 19, 2026 against the four ACS documents listed at the bottom of this page.

How to read a code

The ACS spells the scheme out the same way: "PA = Applicable ACS, I = Area of Operation, C = Task, K2 = Task element (in this example, Knowledge 2)" (Private Pilot ACS, page 66).

Which ACS is which

Other FAA tests (Part 107, mechanic and others) have their own ACS with their own prefixes. This lookup covers the five tests above. FOI codes start with FI because Area I of the flight instructor ACS is coded that way.

K, R and S

• K, knowledge: what you need to know. "The applicant demonstrates understanding of" the item.
• R, risk management: a hazard you need to spot. "The applicant is able to identify, assess, and mitigate risk associated with" the item.
• S, skill: what you do in the airplane. "The applicant exhibits the skill to" do the item.

Your knowledge test report mostly shows K and R codes. The ACS says knowledge and risk management elements "are primarily evaluated during the knowledge testing phase," and skills are tested on the checkride.

What happens with your codes

The ACS notes that your Airman Knowledge Test Report (AKTR) "lists ACS codes that correlate to a specific Task element" for any question you got wrong. Two people use that list:

• Your examiner. On the checkride the evaluator must test "any elements in which the applicant was shown to be deficient on the knowledge test" (Private Pilot ACS). Expect questions on every code on your report.
• Your instructor. Your endorsement for the practical test must certify that you've shown satisfactory knowledge of the areas you missed (14 CFR 61.39(a)(6)(iii)).

So clear them before the checkride: look each code up, read the Task's references in the ACS, practice that area, and go over the list with your CFI. Passing score questions, how long your report is good for, and retests: FAA written test passing score.

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More questions

What do the codes on my FAA knowledge test report mean?

Each one is an Airman Certification Standards (ACS) code for a question you got wrong. The code names the ACS, the Area of Operation, the Task and the element you missed, for example PA.I.C.K2 = Private Pilot ACS, Area I (Preflight Preparation), Task C (Weather Information), knowledge element 2.

What does PA.I.C.K2 mean?

PA is the Private Pilot Airplane ACS (FAA-S-ACS-6C), I is Area of Operation I (Preflight Preparation), C is Task C (Weather Information) and K2 is knowledge element 2: Acceptable weather products and resources required for preflight planning, current and forecast weather for departure, en route, and arrival phases of flight.

What is the difference between K, R and S codes?

K is a knowledge element, R is a risk management element and S is a skill element. The ACS says knowledge and risk management elements are primarily evaluated during the knowledge testing phase; skills are tested on the checkride.

Will the examiner ask about the codes I missed?

Yes. The ACS says the evaluator must test any elements in which you were shown to be deficient on the knowledge test, as applicable.

Do I need an instructor endorsement for my missed codes?

Yes. Under 14 CFR 61.39(a)(6)(iii) your instructor must endorse that you have shown satisfactory knowledge of the subject areas you were deficient in on the knowledge test.