The Part 107 Exam's Most-Missed Topic
The FAA's own quarterly report shows one Part 107 ACS code missed over 78% of the time — Declaration of Compliance. See the data and the trend.
This page is built entirely on the FAA’s own published data — not site telemetry. We have none to offer: this is a new practice site with no users yet, and even once it has some, their drill results wouldn’t be a representative sample of everyone sitting the real exam. The FAA’s Safety Analysis Branch, by contrast, sees every scored knowledge test administered nationwide. When it tells you which ACS code candidates miss most, that is the number worth building a study plan around.
The report
The source is the FAA’s Frequently Missed Knowledge Test ACS Codes report, 2nd Quarter CY25, covering July 1, 2024, through June 30, 2025 (sources/frequently_missed_acs_codes_fy_2025_2q.pdf, p. 1). It’s published quarterly on the FAA’s Airman Knowledge Test Statistics page, and the methodology is stated plainly in the FAA’s own August 2025 Airman Testing Community Advisory (community_advisory_August_2025.pdf, p. 5):
- Based on data in the FAA’s Safety Performance and Analysis System (SPAS), for the specified timeframe.
- Includes only ACS codes administered at least 100 times — enough volume that the number isn’t noise.
- Displays only codes missed more than 70% of the time. Everything else on the real exam — all 130 other UAG knowledge codes — falls below that bar.
The one UAG row
Out of 131 total UAG knowledge codes, exactly one clears the 70% threshold:
| ACS code | Subject | Missed |
|---|---|---|
UA.I.E.K13 |
Declaration of Compliance (DoC) | 78.58% |
(frequently_missed_acs_codes_fy_2025_2q.pdf, p. 1.) No other UAG code appears in the report at all — not because every other topic is easy, but because nothing else clears a 70% miss rate on at least 100 administrations. UA.I.E.K13 is singled out by the FAA’s own measurement as the single hardest thing a Part 107 applicant currently has to know.
The trend — it’s getting worse
The same code appears in the prior report too, two quarters apart in title but a full year apart in coverage: 2nd Quarter CY24, covering July 1, 2023, through June 30, 2024 (sources/frequently_missed_knowledge_test_acs_codes.pdf, p. 1).
| Report | Coverage | UA.I.E.K13 missed |
|---|---|---|
| 2nd Quarter CY24 | 2023-07-01 → 2024-06-30 | 75.87% |
| 2nd Quarter CY25 | 2024-07-01 → 2025-06-30 | 78.58% |
That’s a rise of roughly 2.7 percentage points year over year, on a code that was already the hardest-missed in the prior report too. Whatever is making Declaration of Compliance hard to learn isn’t resolving on its own — if anything, it’s compounding.
Why it lands where it does
UA.I.E.K13 sits in ACS Area I, Task E — Operations Over People — and Area I (Regulations) is 48% of the current Part 107 knowledge test, by far the largest content area (UAG_Information_Bulletin.pdf, p. 4; full breakdown on What’s Actually on the Part 107 Test). The FAA’s hardest-measured code isn’t tucked into a 2% or 5% sliver of the exam — it’s inside the single block most likely to decide whether an applicant clears the required 70% score.
For the regulation itself — what a Declaration of Compliance actually is, who has to file one, how it relates to a Means of Compliance, and the specific modification scenario that quietly invalidates one — see the Operations Over People study guide.
When we last checked
This page reflects the 2nd Quarter CY25 report, the most recent one published as of October 22, 2026. The FAA posts a new quarter’s report on its Airman Knowledge Test Statistics page roughly a month after each quarter closes; we re-check it on the same schedule and will update this page, including the trend table above, when a new quarter’s number is published.
Drill the exact regulation behind this number with Operations Over People practice questions, or read the full Operations Over People study guide for the DoC/MoC detail the FAA’s data says matters most.
Frequently asked questions
- What's the most-missed topic on the Part 107 exam?
- Declaration of Compliance (ACS code UA.I.E.K13) — the only UAG knowledge code the FAA's own quarterly report lists above a 70% miss rate, at 78.58% in the 2nd Quarter CY25 report (frequently_missed_acs_codes_fy_2025_2q.pdf, p. 1).
- Read the Operations Over People guide →
- Is this based on real FAA data, or this site's own quiz results?
- Real FAA data. It's the FAA Safety Analysis Branch's quarterly Frequently Missed Knowledge Test ACS Codes report, based on SPAS data from every scored knowledge test administered nationwide — not telemetry from this or any other practice site.
- Drill operations-over-people questions →
- Is the miss rate for this topic getting better or worse?
- Worse. The prior report (2nd Quarter CY24) showed 75.87% missed; the current report (2nd Quarter CY25) shows 78.58% — a rise of about 2.7 percentage points year over year.
- Read the Operations Over People guide →
- Why does one hard ACS code matter so much for exam prep?
- Because it sits in ACS Area I (Regulations), which is 48% of the current Part 107 exam — the single largest content area. A code the FAA flags as hardest-missed, inside the block worth the most points, is a high-leverage place to study.
- See the full exam weighting →