Test prep
Common Part 107 test mistakes: the reasoning errors that cost points
Most lost points come from reasoning slips, not missing facts: mixing MSL with AGL, misreading a chart number, converting Zulu time the wrong way, or using the wrong unit. Each slip has a quick check, and the rule behind each one is in 14 CFR 107.29, 107.51 and 107.65 or in the AIM.
Why do I miss questions I understand?
The test is multiple choice with a single best answer, and the wrong options are built from the slips below. We do not have FAA data on which questions candidates miss, and we are not going to guess at it. This page lists errors in reasoning that are visible from the rules themselves: each one has a rule source and a short check you can run in your head. The numbers in the worked examples are made up but realistic.
Habit that fixes most of these: before you pick an answer, write the unit next to every number (ft MSL, ft AGL, kt, SM, Z) and say which two numbers you are comparing.
How do I avoid mixing up MSL and AGL?
The Part 107 height limit is above ground level (14 CFR 107.51(b)). Chart airspace limits, airport elevations and Class D ceilings are in feet MSL. A comparison only works when both numbers are in the same unit, so convert first. Altitude MSL equals ground elevation plus height AGL.
Worked example
Converting before you compare
Say a roof survey site sits on ground at 640 ft MSL and the pilot plans 350 ft AGL. The aircraft's altitude is 640 + 350 = 990 ft MSL. If a chart shows a Class C shelf with a floor of 1,200 ft MSL over that spot, 990 ft MSL is below the shelf, so the shelf does not apply at that altitude. If the same shelf label were 40 over 8 (floor 800 ft MSL), 990 ft MSL is inside it and authorization is needed.
The trap answer treats 350 ft as if it were the MSL altitude and compares it with 800. It never gets above the shelf floor, so it concludes the flight is outside. It is not.
Sources (checked 2026-11-14): 14 CFR 107.51 (eCFR); FAA Aeronautical Chart Users' Guide.
See MSL vs AGL on a sectional chart for the obstruction label format.
How do Class E floors trip people up?
Class E is the layer that can start at the surface, at 700 ft AGL, at 1,200 ft AGL, or at a stated MSL altitude, and it is described in the FAA study guide and the AIM. Where a chart does not depict a Class E base, Class E begins at 14,500 ft MSL. The part that needs ATC authorization under 14 CFR 107.41 is Class E designated as a surface area for an airport, not Class E in general.
| Chart sign | What it means | Authorization at 400 ft AGL? |
|---|---|---|
| Dashed magenta line around an airport | Class E surface area | Yes (107.41) |
| Faded magenta band | Class E begins at 700 ft AGL, Class G below | No |
| Faded blue band | Class E begins at 1,200 ft AGL, Class G below | No |
Worked example
Class E that is not a surface area
A pilot flies at 350 ft AGL inside a faded magenta ring far from the airport boundary. Class E starts at 700 ft AGL there, so at 350 ft AGL the pilot is in Class G and needs no airspace authorization. The common error is hearing "magenta" and assuming "needs LAANC". Remote ID, registration and 107.51 limits still apply.
Sources (checked 2026-11-14): AIM chapter 3, section 2 (controlled airspace); FAA Remote Pilot sUAS Study Guide (FAA-G-8082-22); 14 CFR 107.41 (eCFR).
What goes wrong when I read a Class D ceiling?
The number in the dashed blue box is the ceiling in hundreds of feet MSL, not feet AGL and not feet above the airport. A 25 is 2,500 ft MSL. If the number has a minus sign, as in -10, the Class D runs up to, but not including, that altitude. Questions use this to ask how high Class D extends, or whether a given aircraft altitude lies inside it.
Worked example
Is a flight at 400 ft AGL inside?
Say an airport with a tower sits at 1,100 ft MSL and the Class D label reads [25]. The ceiling is 2,500 ft MSL. A drone 400 ft above ground near the field is at about 1,500 ft MSL, which is below 2,500, so it is inside Class D. Authorization is required under 14 CFR 107.41.
Common errors: reading 25 as 2,500 ft AGL (which gives 3,600 MSL at this airport and a wrong ceiling), or as 25 ft, or missing that Class D is a cylinder from the surface so the drone's height does not matter near the airport.
Sources (checked 2026-11-14): FAA Aeronautical Chart Users' Guide; 14 CFR 107.41 (eCFR).
How do I convert Zulu time without errors?
Zulu is UTC, the one time standard used in METAR and TAF. To go from UTC to local, subtract the offset; to go from local to UTC, add it. U.S. offsets from UTC are: Eastern 5 hours (4 in daylight time), Central 6 (5), Mountain 7 (6) and Pacific 8 (7). The supplement has a time conversion table (Figure 27), and the Chart Supplement header gives the airport's offset (for example, "UTC minus 8, or UTC minus 7 during daylight time"). The study guide calls Zulu the term used for UTC.
Worked example
Zulu to local, and back
A TAF is valid until 0200Z. In Pacific daylight time (UTC minus 7) that is 7:00 PM local the evening before. A flight planned for 4:00 PM Eastern daylight time (UTC minus 4) is 2000Z. Two checks help: local time is earlier than UTC in the United States, and a UTC time just after midnight belongs to a different calendar date than the local evening.
The date shown in the TAF matters too. The AIM cautions to confirm the date and time of the TAF, for example that FM100000 means 0000Z on the 10th, not 1000Z.
Sources (checked 2026-11-14): FAA Remote Pilot sUAS Study Guide (FAA-G-8082-22); AIM chapter 7, section 1 (meteorology); FAA-CT-8080-2H Airman Knowledge Testing Supplement.
When do knots and miles per hour get confused?
METAR and TAF winds are in knots. 14 CFR 107.51(a) gives the groundspeed limit as 87 knots (100 miles per hour). Manufacturers often list wind limits in miles per hour or meters per second. One knot is about 1.15 mph. Visibility in METAR is in statute miles, and the Part 107 visibility minimum is 3 statute miles. Do not use nautical miles for visibility.
Worked example
Check the wind against the drone limit
Say the METAR wind is 27018G28KT: from 270 degrees at 18 knots, gusting to 28. In mph that is about 21 gusting to 32. If the aircraft manual lists a 25 mph limit, the gusts exceed it even though 18 sounds modest. The common error is comparing 28 to 25 and, on a different day, comparing a 22 knot wind to a 25 mph limit as if they were the same unit. Convert first.
Sources (checked 2026-11-14): 14 CFR 107.51 (eCFR); AIM chapter 7, section 1 (meteorology).
What is the difference between FM and TEMPO in a TAF?
In the AIM's TAF explanation, FM (FroM) marks a significant change expected at the stated time, and the new conditions replace the earlier ones from that time on. TEMPO marks temporary changes lasting less than 1 hour at a time and less than half of the period stated for the TEMPO group. BECMG marks a change expected gradually inside its period. PROB30 or PROB40 gives a 30 or 40 percent chance of the condition in the stated period.
Worked example
Reading a short TAF
Say a TAF reads: TAF KXYZ 121720Z 1218/1324 18008KT P6SM SCT050 FM122200 20012G20KT 5SM BR BKN015 TEMPO 1300/1303 2SM BR OVC008.
- From 2200Z on the 12th the wind is 200 degrees at 12 gusting 20, visibility 5 SM in mist, ceiling broken at 1,500 ft AGL. The earlier lines no longer apply.
- Between 0000Z and 0300Z on the 13th, temporary periods of 2 SM and overcast at 800 ft AGL are possible.
A flight at 0130Z must plan for the TEMPO values. At 2 SM visibility, the 3 SM minimum of 107.51(c) is not met, and an overcast base at 800 ft AGL leaves at most 300 ft AGL under the 500 ft cloud clearance rule. The common error is reading the TEMPO as the forecast for the whole period, or reading the FM line as an addition to the earlier conditions.
Sources (checked 2026-11-14): AIM chapter 7, section 1 (meteorology); 14 CFR 107.51 (eCFR).
How do I get cloud clearance right?
14 CFR 107.51(d) requires at least 500 ft below the cloud and 2,000 ft horizontally from it. The 500 ft is vertical and applies below the cloud, and 2,000 ft is the horizontal distance. Cloud heights in a METAR are in hundreds of feet AGL (the study guide says sky condition is reported with a three-digit number in hundreds of feet AGL). Flight visibility must be at least 3 statute miles as well.
Worked example
Maximum altitude under a broken layer
The METAR shows BKN012: a broken layer at 1,200 ft AGL. Subtract 500 ft: the highest permitted altitude is 700 ft AGL, and the 400 ft limit is the binding one. If the report shows OVC006, the base is 600 ft AGL, 600 minus 500 is 100 ft AGL, and the clearance is the binding limit. The two common errors are flying up to the base and thinking the 500 ft is a horizontal distance.
Sources (checked 2026-11-14): 14 CFR 107.51 (eCFR); FAA Remote Pilot sUAS Study Guide (FAA-G-8082-22).
What do candidates misread about night and twilight lighting?
14 CFR 107.29 allows flight at night only if the remote pilot completed an initial knowledge test or training under 107.65 after April 6, 2021, and the aircraft has lighted anti-collision lighting visible for at least 3 statute miles with a flash rate sufficient to avoid a collision. The same lighting is required during civil twilight, which runs from 30 minutes before official sunrise to sunrise and from official sunset to 30 minutes after sunset (except in Alaska). You may reduce the intensity but may not extinguish the lights. 14 CFR 1.1 defines night as the time between the end of evening civil twilight and the beginning of morning civil twilight.
Worked example
Lights in the half hour after sunset
Say official sunset is 7:42 PM. Civil twilight ends at 8:12 PM. The anti-collision lights are required from 7:42 PM, not from 8:12 PM. The common error treats twilight as daytime. A second error is thinking a pilot with a 2019 certificate may fly at night just by adding lights; the knowledge test or training date also matters.
Sources (checked 2026-11-14): 14 CFR 107.29 (eCFR); 14 CFR 107.65 (eCFR); 14 CFR 1.1 (eCFR).
See night operations.
Does my Part 107 certificate expire after 24 months?
No. The certificate does not expire, but 14 CFR 107.65 says you may not exercise remote pilot in command privileges unless within the previous 24 calendar months you passed an initial knowledge test, completed recurrent training, or, as a Part 61 pilot with a current flight review, completed the training in 107.74. A "valid" certificate and current recency are different things.
Worked example
Valid but not current
Say you passed the test in June 2024 and took no recurrent training. In July 2026 you still hold the certificate, but 24 calendar months have passed, so you may not act as remote pilot in command until you complete recurrent training. The free FAA course is on FAASafety.gov. The wrong answers on the test often say "the certificate expires" or "you must retake the knowledge test", which the rule does not require.
Sources (checked 2026-11-14): 14 CFR 107.65 (eCFR); FAA: Become a Certificated Remote Pilot; FAASafety.gov (recurrent training).
See recurrent training.
How can I practice catching these slips?
Use the free chart questions on Figures 20, 26 and 69 for the MSL-to-AGL and shelf-floor slips, and run a timed set of operating-rules questions for clouds, speed and lights. After each miss, write one line stating which unit or rule you got wrong. A weekly review of those lines shows your own pattern, which is more useful than any general list. The two-week plan puts a mistake review on day 13.
Free practice questions on this topic
3 original questions from the Sectional Cue bank. Try each one, then open the answer.
Class C shelf floor
1. In Figure 20, the Norfolk Class C label just north of the Norfolk Intl data block reads 40 over 12. Assume the ground under that shelf is 20 ft MSL. Does a drone at 300 ft AGL there need a Class C authorization? (uses Figure 20, open the free chart lesson)
- Yes, because Class C starts at the surface anywhere inside the outer magenta circle
- No, because the shelf floor is 1,200 ft MSL and the drone is at about 320 ft MSL
- Yes, because the 12 means the shelf begins 120 ft above the ground
Show answer and explanation
B. No, because the shelf floor is 1,200 ft MSL and the drone is at about 320 ft MSL
Class C altitudes are in hundreds of feet MSL, so 40 over 12 is a shelf from 1,200 ft MSL to 4,000 ft MSL. A drone at 300 ft AGL over 20 ft ground is at about 320 ft MSL, below the shelf, so 14 CFR 107.41 does not require a Class C authorization for that altitude. Only the inner area marked SFC starts at the surface, and the 12 is 1,200 ft MSL, not 120 ft AGL.
Source: FAA-CT-8080-2H, Figure 20; Chart Users' Guide; 14 CFR 107.41
Shelf floor calculation
2. In Figure 69, the obstruction 1037 (977) lies near the Class C sector labeled 40 over 15. Using it to estimate ground level, would a drone at 400 ft AGL there be inside that Class C sector? (uses Figure 69, open the free chart lesson)
- Yes; 400 ft AGL is above the 150 ft floor
- No; that sector begins at 4,000 ft MSL
- No; it would be at about 460 ft MSL, below the 1,500 ft MSL floor
Show answer and explanation
C. No; it would be at about 460 ft MSL, below the 1,500 ft MSL floor
The ground is about 1,037 minus 977, or 60 ft MSL, so 400 ft AGL is about 460 ft MSL. The bottom number, 15, is the floor in hundreds of feet MSL, so the sector starts at 1,500 ft MSL and the drone is below it. There is no 150 ft floor, and 4,000 ft MSL is the ceiling, not the floor.
Source: FAA-CT-8080-2H, Figure 69; Chart Users' Guide; 14 CFR 107.41
Class D ceiling
3. In Figure 69, a remote pilot has authorization to fly in the Kingsville NAS (NQI) Class D near area 2 while the tower operates. Per the dashed blue box with 25, what is the top of that Class D? (uses Figure 69, open the free chart lesson)
- 2,500 ft AGL
- 2,500 ft MSL
- 8,000 ft MSL
Show answer and explanation
B. 2,500 ft MSL
The number in the dashed blue box is the Class D ceiling in hundreds of feet MSL, so 25 means 2,500 ft MSL. Class D ceilings are not charted in AGL. 80 in the data block (*L 80) is the longest runway, 8,000 ft, not an altitude.
Source: FAA-CT-8080-2H, Figure 69; Chart Users' Guide; 14 CFR 107.41
Related guides
- MSL vs AGL: altitude math on a sectional chart
- Part 107 operating rules: altitude, speed, visibility and clouds
- How to read a TAF for the Part 107 test
- Part 107 night operations: lights, twilight and training
- A two-week Part 107 study plan, day by day
- All Part 107 guides
Study the charts on your phone
Sectional Cue has 1150+ original questions with explanations, 27 FAA figures you can tap to read, and timed 60-question rehearsals. About 152 questions and three chart lessons are free.
Sources
- 14 CFR 107.51 (eCFR), checked 2026-11-14
- 14 CFR 107.29 (eCFR), checked 2026-11-14
- 14 CFR 107.65 (eCFR), checked 2026-11-14
- AIM chapter 7, section 1 (meteorology), checked 2026-11-14
- AIM chapter 3, section 2 (controlled airspace), checked 2026-11-14
How this page was made: written by Certloom Learning from the sources above, with the rules checked against the current regulation text. Practice items are original questions from the app's reviewed bank. Spot an error? certloomlearning@gmail.com.