NCCCO specialty written exams compared: LAT, TLL, TSS and STC

For the Core exam itself, see the Core study guide, which splits study time by the Core domain weights.

The four exams side by side

✓ The current candidate handbook (cover MCO CH REV 01/25) prints these figures in the heading of each written outline (printed pages 2, 4 and 11):

	Core (for reference)	LAT, TLL, TSS specialty	STC
Questions	95	28	80
Time	90 minutes	60 minutes	90 minutes
Calculator	Not permitted	Permitted	Not permitted
Domain 1: Site	approx. 22%	approx. 23%	approx. 17%
Domain 2: Operations	approx. 28%	approx. 23%	approx. 45%
Domain 3: Technical Knowledge	approx. 23%	approx. 19%	approx. 21%
Domain 4: Load charts	approx. 27%	approx. 35%	approx. 17%

The three specialties share one outline and one set of figures. The handbook says each specialty exam only asks about cranes in its own specialty area, so a TLL candidate does not get lattice boom questions.

The numbers below are our arithmetic from those figures, not published counts. The handbook says "approximately", so allow a question or two either way.

	Core	Specialty	STC
Load chart questions (questions × weight)	about 26	about 10	about 14
Average time per question	just under 1 minute	a little over 2 minutes	about 1 minute 7 seconds

Two things stand out. A specialty exam gives you more than twice the time per question that Core does, and it lets you use a calculator, because its load chart questions carry the most weight on any of the four outlines. STC runs the other way: Operations is nearly half the exam, load charts are the smallest share, and all of the arithmetic is by hand.

What the specialty outline asks you to do with a chart

The specialty load chart domain (printed page 4) has three tasks. In our words:

1. Know the parts of a load chart: its notes, the specifications, the range diagram, the work area diagram, the boom and jib erection charts and the rated capacity charts.
2. Use a chart for a given configuration to find the maximum radius for placing a load, the gross capacity and the net capacity.
3. Tell the difference between the maximum line pull and the safe working load of running ropes.

The rest of the specialty outline is about the machine rather than the paperwork: boom assembly and disassembly, outriggers, stabilizers and crawlers, pick and carry on rubber or crawlers, boom and jib limiting devices, boom stops and brake locks, two-blocking on telescopic and lattice booms, and standing rope inspection.

A worked net capacity example (invented numbers)

This is the kind of chart work the outline describes. Every number here is made up and does not come from any real crane, manufacturer chart or exam chart.

An invented chart lists 21,500 lb gross capacity at a 30 ft radius for the boom length in use. Its notes say the hook block, any stowed jib and all rigging must be deducted. The setup has:

• hook block: 650 lb
• stowed jib deduction from the chart notes: 1,200 lb
• slings and shackles: 150 lb

Net capacity = 21,500 − 650 − 1,200 − 150 = 19,500 lb.

A load of 18,200 lb is within that net capacity. It uses 18,200 ÷ 19,500, about 93%, of what is available at that radius. With a calculator allowed on the specialty exams, you can afford to check each subtraction. The usual errors are taking the wrong radius row and forgetting a deduction the chart notes require.

What the STC outline asks

✓ STC is described in the handbook (printed page 10) as a subcategory of TSS, built for service truck cranes, typically with booms of 10 to 35 ft and capacities of 1 to 7 tons, often run by remote or pendant control. The same page says a TSS certification already covers service truck cranes, but an STC certification does not cover larger fixed cab telescopic cranes.

Its load chart domain (printed page 12) goes into more detail than the specialty one, even though it carries less weight. It lists chart notes, rated capacity charts and stability charts, then maximum radius, gross capacity, net capacity, load moment and intermediate values on capacity charts for boom length, radius and boom angle. Its Domain 2 also includes outriggers and stabilizers with position sensor monitors, and it lists ASME B30.5, OSHA 1910.180, OSHA 1926 Subpart CC and SAE 765A among the standards to recognize.

Hand arithmetic for STC (invented numbers)

With no calculator, the methods have to work on paper. Again, these numbers are invented.

• Load moment. A 3,000 lb load at a 15 ft radius is 3,000 × 15 = 45,000 ft-lb.
• Intermediate values. An invented chart shows 4,000 lb at 20 ft and 3,200 lb at 25 ft, and you need 22 ft. Some chart notes allow a straight-line value between rows: 4,000 − (2 ÷ 5 × 800) = 3,680 lb. Others require the value for the next longer radius, which is 3,200 lb. Read the notes on the chart you are given before choosing a method.

The January 2023 switch to generic charts

CCO announced in a September 2022 notice that from 1 January 2023 each Mobile Crane Operator specialty exam (LAT, TLL and TSS) would be a single exam using a generic load chart. Before that, candidates chose a chart from a particular manufacturer to test on. CCO's stated reason was that its certifications have never been tied to one manufacturer.

What this means for preparation:

• Practice on the skill, not one maker's layout. Charts differ in where the notes sit and how deductions are listed. Use several unfamiliar charts so you have to find those things each time.
• Be careful with older material. Practice books and question sets written before 2023 may assume you picked a manufacturer chart. The chart method still applies, but the exam no longer asks you to choose a make.
• Learn every part of the chart, not just the capacity table. The specialty outline lists notes, specifications, range and work area diagrams and erection charts, so expect questions that send you to those parts.

Our load chart practice uses invented charts, not manufacturer or exam charts, for repeated work on radius, gross capacity and deductions. If you need the basics first, start with how to read a crane load chart.

Where CCO's documents disagree

These differences appear in documents CCO itself publishes. When two sources differ, use the newest handbook revision and confirm with CCO before your test date.

• Chart wording versus the generic chart notice. The 01/25 handbook still names the specialty Domain 4 "Manufacturers' Load Charts" in its summary and still refers to manufacturers' charts in specialty task 4.2. The 2022 notice says the specialty exams use a generic chart. The STC outline also uses the "Manufacturers' Load Charts" name, and the notice is about the three specialties, not STC, so check which chart STC uses when you register.
• Specialty question count. ✓ The January 2024 handbook and the September 2023 handbook (printed page 4 in both) list 26 questions in 60 minutes. The 01/25 handbook lists 28. The domain weights are the same in all three. The 01/25 revision also renames Domain 1 from "Setup" to "Site" and adds the line pull task (4.3).
• STC question count and weights. ✓ The January 2024 handbook (printed page 11) lists STC as 70 questions in 90 minutes, with Operations at approximately 44%. The 01/25 handbook lists 80 questions and 45%. The 01/24 weights add up to 99%, the 01/25 weights to 100%.
• Time and calculator rules are the same in all three revisions: 60 minutes with a calculator for the specialties, 90 minutes without for STC.

CCO's live Mobile Crane Operator certification overview page said 26 questions per specialty when we checked it on 17 Oct 2026. The 01/25 handbook says 28. Both are current CCO documents, so ask CCO which count applies before your test date. For STC, check the revision code at the bottom of the handbook cover: 70 questions matches the 01/24 handbook, and 80 matches 01/25.

Choosing the specialty, and booking it

The specialty follows the crane you run. The handbook (printed page 1) defines TLL as cranes whose operator station rotates with the upper works, which it says includes walk-around, platform and cab-operated boom trucks. TSS covers cranes with a fixed operator's station. Each added designation's certification expires on the same date as the first one.

You have 12 months after passing your first exam to pass the corresponding exams for that designation, and for STC the written and practical must be passed within 12 months of each other, in either order. Fees, retake waits and that window are in written test cost and retakes.

LAT, TLL and TSS candidates also need Core. To check your Core topics first, take the free 10-question check. It is scored by the Core outline domains, so it shows where Core needs work. It does not test the specialty outline.

Sources

Show the list

• Mobile Crane Operator Candidate Handbook, CCO, cover MCO CH REV 01/25, inner pages REV 06/24. Printed pages 1, 2, 4, 10, 11 and 12. Retrieved 20 Oct 2026.
• Mobile Crane Operator Candidate Handbook, January 2024 revision, CCO, MCO CH REV 01/24, printed pages 4 and 11. Retrieved 20 Oct 2026.
• Mobile Crane Operator Candidate Handbook, September 2023 revision, CCO, MCO CH REV 09/23, printed page 4. Retrieved 20 Oct 2026.
• Mobile Crane Operator certification overview, CCO, live page. Checked 17 Oct 2026; it returned 403 to an automated fetch on 20 Oct 2026, so check it in a browser.
• CCO Announces Updates to Mobile Crane Operator Specialty Exam Load Charts, CCO, September 2022. Retrieved 20 Oct 2026.