- The CAX has 100 scored questions plus 5 unscored validation items, 105 total, in 2 hours 30 minutes.
- You need 70% to pass, and the 2025 pass rate was 99.17% across 20,530 tests.
- All 12 content areas map to FAA-S-ACS-7B, effective May 31, 2024 - study the ACS, not guesswork.
- A passing knowledge test report is generally valid 24 calendar months before your practical test.
CAX Exam Overview: Format, Fee, and Timing
The Commercial Pilot Airplane knowledge test - referred to by its FAA code, CAX - is administered by PSI Services LLC on behalf of the FAA. It's a computer-based exam with 100 scored multiple-choice questions and 5 additional unscored validation questions used by the FAA to evaluate future test items, for 105 total questions. You get 2 hours and 30 minutes, and you need a score of 70% or higher to pass.
The current fee is $175 plus applicable tax, payable when you schedule through PSI. Every question on the CAX is built against 12 defined content areas, and understanding how those areas are structured is the difference between studying broadly and studying efficiently. If you haven't already reviewed the full CPL Requirements 2026: Eligibility, Prerequisites & How to Qualify checklist, do that first - it clarifies what you need in hand before you can even sit for this test.
The 12 CPL Content Areas Explained
The FAA organizes the Commercial Pilot Airplane knowledge test into 12 domains. None of them stand alone - questions routinely blend two areas into a single scenario, for example a weight and balance problem set against density altitude performance limits. Below is what each domain actually demands.
Domain 1: Federal Aviation Regulations
Covers Part 61 and Part 91 as they apply specifically to commercial operations - not just private pilot rules repeated.
- Commercial pilot privileges and limitations under Part 61
- Carriage of persons or property for compensation
- Recordkeeping and certificate currency rules
Domain 2: Aerodynamics and Principles of Flight
Goes beyond private-level lift and drag into load factor, stability, and performance at the edges of the flight envelope.
- Load factor in steep turns and maneuvering
- Stall speed relationships to bank angle and weight
- High-performance aircraft handling characteristics
Domain 3: Aircraft Systems and Flight Instruments
Tests understanding of powerplant, electrical, and instrument systems found in complex and high-performance airplanes.
- Turbocharging, cowl flaps, and constant-speed propellers
- Pitot-static and gyroscopic instrument errors
- Retractable gear and system failure scenarios
Domain 4: Weight and Balance
Requires actual arithmetic - computing CG, moment, and loading limits from given data, not just conceptual recall.
- Computing center of gravity from weight and arm data
- Determining if a loaded aircraft is within limits
- Effects of shifting or adding cargo/fuel on CG
Domain 5: Aircraft Performance and Limitations
Chart-reading heavy: takeoff/landing distance, climb performance, and density altitude effects using POH-style tables.
- Interpolating performance charts for nonstandard conditions
- Density altitude impact on takeoff and climb
- Runway length and obstacle clearance calculations
Domain 6: Weather Theory
Focused on the physics behind weather - fronts, stability, turbulence, and icing formation mechanisms.
- Frontal passage and associated hazards
- Atmospheric stability and thunderstorm development
- Structural icing conditions
Domain 7: Weather Reports and Forecasts
Practical decoding of METARs, TAFs, and other products used for real go/no-go flight planning decisions.
- Decoding METAR and TAF products
- Interpreting AIRMETs, SIGMETs, and area forecasts
- Using weather charts to plan a route
Domain 8: Navigation and Flight Planning
Cross-country planning math: fuel, groundspeed, wind correction, and both pilotage and electronic navigation methods.
- Flight plan fuel and time calculations
- Wind correction angle and groundspeed problems
- VOR and GPS navigation interpretation
Domain 9: Airspace Classes and Requirements
Requirements and entry procedures for each airspace class, plus special use airspace considerations.
- Class B, C, D, E, and G entry and equipment requirements
- Special use airspace restrictions
- Weather minimums by airspace class
Domain 10: Airport Operations and Procedures
Traffic pattern procedures, runway markings, and communication requirements at towered and non-towered fields.
- Airport marking and lighting interpretation
- Traffic pattern entry and communication procedures
- Right-of-way and collision avoidance rules
Domain 11: Aeromedical Factors
Physiological effects relevant to commercial-level flying, including hypoxia, fatigue, and altitude illness.
- Hypoxia types and symptoms
- Effects of alcohol, drugs, and fatigue on performance
- Spatial disorientation and vestibular illusions
Domain 12: Aeronautical Decision Making
Scenario-based judgment questions evaluating risk management in commercial operating environments.
- Risk assessment models (PAVE, DECIDE, etc.)
- Recognizing hazardous attitudes
- Single-pilot resource management scenarios
Key Takeaway
Domains 4 and 5 (Weight and Balance, Performance) are computation-heavy - budget extra practice time solving full problems, not just reviewing concepts.
Registration and Eligibility Mechanics
Before you can even schedule the CAX through PSI, you must be at least 16 years old and present an accepted ground-school completion document or an instructor endorsement. Full certificate issuance - actually being granted the commercial pilot certificate - requires you to be 18, demonstrate English proficiency, hold at least a private pilot certificate, complete the required endorsements, log the necessary aeronautical experience, and pass a practical test. Under Part 61, airplane applicants generally need 250 flight hours.
For a step-by-step breakdown of every prerequisite, see CPL Requirements 2026: Eligibility, Prerequisites & How to Qualify. If you're still asking basic questions like what the certificate actually is, start with What Is CPL? or CPL Meaning before diving into domain-level prep.
| Requirement | Detail |
|---|---|
| Minimum age (knowledge test) | 16 years old |
| Minimum age (certificate issuance) | 18 years old |
| Prerequisite certificate | At least Private Pilot certificate |
| Flight hours (Part 61) | 250 hours generally required |
| Test fee | $175 plus applicable tax |
| Test length | 2 hours 30 minutes, 105 total questions (100 scored) |
| Passing score | 70% |
| Score report validity | Generally 24 calendar months before the practical test |
Which Domains Carry the Most Weight
The FAA does not publish a precise question count per domain for the CAX, but candidates and instructors consistently report certain domains showing up more frequently on real exam attempts. Regulations (Domain 1), Weather Reports and Forecasts (Domain 7), and Navigation and Flight Planning (Domain 8) tend to appear across a large share of question sets, since they involve numerous discrete regulatory citations and chart-reading scenarios that lend themselves to many distinct question variations.
Domain 4 (Weight and Balance) and Domain 5 (Performance and Limitations) are lower in raw question count but disproportionately time-consuming, since each question typically requires working through a chart or calculation rather than recalling a fact. Plan your 2 hours 30 minutes accordingly - don't let a handful of computation-heavy questions eat time you need for the rest of the exam.
For a broader discussion of what makes the exam challenging in practice, read How Hard Is the CPL Exam? Complete Difficulty Guide 2026, and check CPL Pass Rate 2026: What the Data Shows for the current pass-rate context.
Mapping Domains to a Study Schedule
Rather than studying domains in the order the FAA lists them, sequence your review so foundational domains come first and computation-heavy domains get isolated blocks with no distractions. A simple four-week structure built around the 12 domains looks like this:
Foundations
- Domain 1: Federal Aviation Regulations
- Domain 9: Airspace Classes and Requirements
- Domain 10: Airport Operations and Procedures
Aircraft Knowledge
- Domain 2: Aerodynamics and Principles of Flight
- Domain 3: Aircraft Systems and Flight Instruments
Calculation-Heavy Domains
- Domain 4: Weight and Balance
- Domain 5: Aircraft Performance and Limitations
- Domain 8: Navigation and Flight Planning
Weather and Judgment
- Domain 6: Weather Theory
- Domain 7: Weather Reports and Forecasts
- Domain 11: Aeromedical Factors
- Domain 12: Aeronautical Decision Making
Whatever cadence you use, cycle back through weak domains with timed practice sets rather than rereading notes passively - recognition under time pressure is what the actual 2 hour 30 minute test demands. For a condensed reference to keep nearby during this final review phase, bookmark the CPL Cheat Sheet 2026: One-Page Review of Must-Know Facts, and for a fuller preparation framework see the CPL Study Guide 2026: How to Pass on Your First Attempt.
After the Knowledge Test
Passing the CAX gets you a knowledge test report, which is generally valid for 24 calendar months before you must complete the practical test. That window matters for scheduling - if your flight training stretches longer than expected, confirm your report hasn't expired before you show up for your checkride.
Passing the knowledge test doesn't grant privileges on its own. Certificate issuance still requires meeting the age, experience, and endorsement requirements outlined earlier, and once you're certificated, exercising commercial pilot privileges remains subject to flight-review, recency, and medical requirements. Confirm your exact passing threshold and scoring mechanics in CPL Passing Score 2026: Exactly What You Need to Pass, and check current testing windows in CPL Exam Dates 2026: Testing Windows, Deadlines & Scheduling before you lock in a date.
You can run full-length timed simulations covering all 12 domains at CPL Exam Prep's practice test platform to gauge readiness before you pay the $175 PSI fee.
Why These Domains Matter on the Job
These aren't abstract test categories - they map directly to what commercial operators expect a working pilot to know cold. Charter operators, aerial survey companies, flight schools hiring CFIs, and regional carriers building toward an ATP all assume competency across weight and balance, performance planning, weather interpretation, and decision-making under Part 135 or Part 91 operations. Weak spots in Domain 4, 5, or 12 knowledge tend to surface again during initial operating experience, not just on a written test.
If you're weighing whether the investment of time and the $175 test fee - plus the broader training costs - pays off, review CPL Certification Cost 2026: Complete Pricing Breakdown alongside CPL Salary Guide 2026: Complete Earnings Analysis and Is the CPL Certification Worth It? Complete ROI Analysis 2026. For a look at where the certificate actually leads, see CPL Jobs and general background at CPL Training or CPL Certification.
Key Takeaway
Study the 12 domains as job-relevant skills, not test trivia - operators evaluate the same competencies during hiring and line checks.
Frequently Asked Questions
The Commercial Pilot Airplane knowledge test (CAX) covers 12 content areas, ranging from Federal Aviation Regulations to Aeronautical Decision Making, all aligned to FAA-S-ACS-7B.
The exam has 100 scored questions and 5 unscored validation questions, for 105 total, with 2 hours 30 minutes allowed and a 70% passing score required.
Weight and Balance (Domain 4) and Aircraft Performance and Limitations (Domain 5) are frequently reported as the most time-consuming because they require working full calculations rather than recalling facts.
A passing knowledge test report is generally valid for 24 calendar months before you must complete the practical test.
No. The knowledge test only requires you to be at least 16 with an accepted ground-school completion document or instructor endorsement. The 250-hour Part 61 requirement and other experience apply to certificate issuance, not the knowledge test itself.