How this ranking works

The ranking below is based on three factors: syllabus volume (how much material you need to cover), calculation demand (how much of the subject requires maths and chart work rather than recall), and time pressure in the exam (how tight the question-to-time ratio is in the real sitting). Each subject also includes a study hours estimate, which reflects the range most modular students report spending before reaching consistent 85% mock scores.

These rankings reflect the consensus of ATPL students who have sat all 13 subjects, and they apply to the EASA ECQB question bank. Individual experience will vary based on prior knowledge, a student with an engineering background will find AGK easier than a student without one, but the overall difficulty curve is consistent enough to plan around.

Important caveat

Difficulty and priority are not the same thing. Some of the easiest subjects are the ones you should sit first, to bank passed subjects early. Some of the hardest subjects need the most calendar time, not necessarily the most intense study. The ranking below tells you how hard each subject is; the study order guide tells you when to tackle them.

Quick reference: all 13 subjects at a glance

# Subject Difficulty Est. Study Hours Calculation Heavy?
1 General Navigation Hard 150 to 250 hrs Yes
2 Performance Hard 100 to 160 hrs Yes
3 Flight Planning Hard 80 to 130 hrs Yes
4 Aircraft General Knowledge Hard 100 to 160 hrs Partly
5 Instrumentation Medium 80 to 130 hrs Partly
6 Meteorology Medium 80 to 130 hrs No
7 Radio Navigation Medium 60 to 100 hrs Partly
8 Principles of Flight Medium 60 to 100 hrs No
9 Air Law Medium 60 to 90 hrs No
10 Operational Procedures Manageable 40 to 70 hrs No
11 Human Performance Manageable 40 to 70 hrs No
12 Mass and Balance Manageable 30 to 55 hrs Yes (simple)
13 Communications Manageable 25 to 45 hrs No
Estimated study hours per subject (midpoint of range)
General Nav
~200 hrs
AGK
~130 hrs
Performance
~130 hrs
Flight Planning
~105 hrs
Instrumentation
~105 hrs
Meteorology
~105 hrs
Radio Navigation
~80 hrs
Principles of Flight
~80 hrs
Air Law
~75 hrs
Op Procedures
~55 hrs
Human Performance
~55 hrs
Mass and Balance
~43 hrs
Communications
~35 hrs
From ATPLSTUDY
Free Practice Tests
6,000+ questions across all 13 subjects
EASA-aligned questions with full answer explanations for every subject in this ranking. Free, no account needed. Start wherever you are in your studies.
Start Practising Free

Each subject in detail

Click any subject below to expand the full breakdown, including what makes it difficult, what students most often struggle with, and which other subjects share content with it.

1
General Navigation
150 to 250 hours Calculation heavy ~2 min per question
Hard +
Key topics
Chart work, flight computer (CRP-5), time/speed/distance, compass errors, great circle vs rhumb line, dead reckoning, ETOPS, drift and wind correction
Why students struggle
The combination of a large syllabus and tight time pressure is unforgiving. Many students are not fast enough on the flight computer by exam day, and chart interpretation requires visual practice that only comes with repetition.

General Navigation is the subject that most frequently causes students to need a re-sit or to run short of sittings. The flight computer (CRP-5 or equivalent) needs to be second nature before you enter the exam room. Do not start full mocks until you can use it without thinking about the mechanics. The syllabus is also genuinely broad, covering celestial navigation concepts that require careful study even if they appear infrequently.

Content overlap: Flight Planning, Radio Navigation
2
Performance
100 to 160 hours Calculation heavy
Hard +
Key topics
Takeoff and landing performance charts, TODA/TORA/ASDA, obstacle clearance, climb gradients, en-route performance, Class A/B/C aircraft, V-speeds
Why students struggle
Performance charts are not intuitive. Reading them accurately under time pressure while accounting for slope, wind, temperature, and elevation corrections together requires substantial practice with real chart examples.

Performance ranks second not because the underlying theory is as broad as General Navigation, but because the exam places very specific demands on chart-reading accuracy. A student who understands all the theory but has not spent enough time drilling chart interpretation will lose marks consistently. Pair Performance study with Principles of Flight, as the aerodynamic foundations inform each other.

Content overlap: Principles of Flight, Flight Planning
3
Flight Planning and Monitoring
80 to 130 hours Calculation heavy
Hard +
Key topics
Fuel planning, alternate requirements, IFR flight plans, ICAO flight plan form, point of no return, point of equal time, en-route calculations, ATC flight plan filing
Why students struggle
Flight Planning borrows calculation methods from General Navigation and fuel knowledge from Performance. Students who have not yet consolidated both of those subjects often find Flight Planning confusing because the foundations are not yet solid.

Most students find Flight Planning easier once General Navigation is well established, since the fuel and navigation calculations use the same tools. Study it after, or concurrently with, General Navigation and Performance. The ICAO flight plan form is a topic many students underestimate: it appears in the exam with specific questions about field formats and requirements that need dedicated study time.

Content overlap: General Navigation, Performance
4
Aircraft General Knowledge (AGK)
100 to 160 hours Partly calculation
Hard +
Key topics
Piston and turbine engines, fuel systems, hydraulics, pneumatics, electrical systems, ice and rain protection, pressurisation, landing gear, flight controls, avionics
Why students struggle
AGK has an enormous content volume. Students without an engineering or technical background find the depth of systems knowledge required very demanding. Many topics require genuine understanding, not just recall, because exam questions test edge cases and failure modes.

AGK sits at number four because the sheer volume of technical systems content makes it one of the most time-intensive subjects to prepare. Study it concurrently with Instrumentation: the two subjects share significant content on aircraft sensors, avionics, and system components. Covering shared content once and then applying it in both question banks is significantly more efficient than studying each subject in isolation.

Content overlap: Instrumentation, Principles of Flight
5
Instrumentation
80 to 130 hours Partly calculation
Medium +
Key topics
Pitot-static system, altimetry and altimeter errors, gyroscopic instruments, attitude indicators, magnetic compass errors, EFIS, FMS, autopilot systems, ACAS/TCAS, GPWS/TAWS
Why students struggle
Instrument errors require precise understanding to answer correctly. Altimetry errors in particular, such as the effects of non-standard temperature and pressure on indicated versus true altitude, are a consistent source of exam marks lost to imprecise recall.

Instrumentation is the natural companion to AGK, and most students find it easier once AGK systems content is established. The altimetry and compass error sections are the areas that most consistently produce wrong answers, even from students who feel they understand the material. Revisit these sections with question bank practice more than once to ensure the distinctions are solid.

Content overlap: AGK, Radio Navigation
6
Meteorology
80 to 130 hours No calculation
Medium +
Key topics
Atmosphere structure, pressure systems, frontal weather, clouds and precipitation, METAR and TAF decoding, icing, thunderstorms, windshear, jet streams, climatology
Why students struggle
Meteorology has a large syllabus, and while there are no complex calculations, the question bank contains many questions that are very specifically worded around process and cause-and-effect relationships. Surface knowledge is not enough.

Meteorology is one of the most content-rich subjects in the non-calculation category. Students who underestimate it because it lacks maths tend to score in the low 80s on mocks when they expect to score in the high 80s. METAR and TAF decoding, cloud types, and icing mechanisms are all well-represented in the exam. Treat it with the same rigour as the technical subjects.

Content overlap: Operational Procedures, Performance
7
Radio Navigation
60 to 100 hours Partly calculation
Medium +
Key topics
VOR, DME, ILS, ADF/NDB, GNSS/GPS, radar (primary and secondary), radio wave propagation, HF/VHF/UHF characteristics, RNP and RNAV, area navigation
Why students struggle
Radio navigation requires understanding how each system works, not just its purpose. ILS error interpretation and VOR bearing questions are consistently answered incorrectly by students who memorised the system without understanding the geometry behind it.

Radio Navigation sits at number seven because its difficulty is bounded by its syllabus size. Once the core systems are well understood, the question bank rewards that understanding consistently. The ILS section typically requires the most revision time, as error interpretation questions require spatial reasoning that takes practice to become reliable.

Content overlap: Instrumentation, General Navigation
8
Principles of Flight
60 to 100 hours Mostly conceptual
Medium +
Key topics
Lift and drag, aerofoil theory, stall and stall speeds, high-lift devices, stability and control, compressibility effects, swept wing characteristics, helicopter aerodynamics
Why students struggle
High-speed aerodynamics (compressibility, Mach effects, swept wing behaviour) is an area that rewards genuine understanding but is difficult to pass on memorisation alone. The helicopter section can also catch students off guard if left unrevised.

Principles of Flight is a subject where the difficulty is concentrated in specific areas rather than spread across the whole syllabus. Basic aerofoil and lift/drag theory is accessible. Compressibility effects and high-speed aerodynamics require more careful study. Pair this subject with Performance to exploit the shared aerodynamic foundations in both syllabi.

Content overlap: Performance, AGK
9
Air Law
60 to 90 hours Recall based
Medium +
Key topics
ICAO Annexes, airspace classifications, rules of the air, SERA, flight crew licensing, accident investigation, ATC procedures, airworthiness requirements, noise regulations
Why students struggle
Air Law is detail-dense. Specific numbers, distances, and time limits within regulations are tested precisely. Students who understand the general principles but cannot recall specific values often miss marks on questions that hinge on exact regulatory figures.

Air Law sits in the medium category despite being essentially recall-based, because the volume of specific regulatory detail that needs to be memorised accurately is substantial. The question bank for Air Law is also one of the more strictly worded: knowing the concept is often not enough if you cannot recall the specific value or exception the question is testing.

Content overlap: Operational Procedures, Communications
10
Operational Procedures
40 to 70 hours Recall based
Manageable +
Key topics
Emergency procedures, fire and smoke, ditching, search and rescue, cargo handling, dangerous goods, noise abatement, low-visibility operations, wake turbulence categories
Why students struggle
Students occasionally underestimate Operational Procedures because it lacks any calculation requirement. The dangerous goods and emergency procedures sections contain specific procedural details that are tested with precision and need dedicated revision.

Operational Procedures is a manageable subject with a focused syllabus. Emergency procedures, dangerous goods classifications, and low-visibility operations are the sections that warrant the most attention. This subject pairs well with Air Law and Meteorology in a study phase, as all three are recall-based and can be rotated through efficiently.

Content overlap: Air Law, Meteorology
11
Human Performance and Limitations
40 to 70 hours Recall based
Manageable +
Key topics
Human factors models, perception and cognition, stress and workload, fatigue and sleep, vision and hearing, hypoxia, spatial disorientation, crew resource management, threat and error management
Why students struggle
Human Performance questions are often subtle, with multiple answers that could plausibly be correct. The CRM and threat and error management sections require careful reading, as the exam tests the nuances of human factors models rather than broad generalisations.

Human Performance is one of the most accessible ATPL subjects in terms of content volume, but students occasionally find the question phrasing more subtle than expected. Because the material is based on research and models rather than hard technical facts, questions sometimes test your understanding of the specific framework being described. Familiarity with the question bank is particularly valuable here.

Content overlap: Operational Procedures
12
Mass and Balance
30 to 55 hours Simple calculations
Manageable +
Key topics
Centre of gravity calculations, moment arms, loading envelopes, trim calculations, basic aeroplane and helicopter loading, cargo loading principles
Why students struggle
The calculations are not difficult once the method is understood, but students who have not practised the full range of calculation types, including both aircraft and envelope problems, occasionally encounter question formats they have not seen before.

Mass and Balance is one of the best subjects to tackle early in your ATPL preparation. The syllabus is focused, the calculations are straightforward once the method is understood, and passing it early gives you a banked subject and a confidence foundation for the harder calculation work ahead. It is a good introduction to the exam format before the difficulty escalates.

Content overlap: Performance (loading and limits)
13
Communications
25 to 45 hours No calculation
Manageable +
Key topics
VHF and HF radio procedures, SELCAL, ATIS, distress and urgency calls, ACARS, CPDLC, phonetic alphabet, frequency allocation, read-back requirements
Why students struggle
Very few students struggle meaningfully with Communications. The only area that occasionally produces wrong answers is the distinction between VFR and IFR communications procedures, which are sometimes confused when studied together too quickly.

Communications is the easiest ATPL subject by a clear margin. The syllabus is short, there are no calculations, and the question bank is one of the smallest in the ECQB. Most students pass comfortably with focused study over four to six weeks. Sit it in your first sitting to bank an early pass and establish your exam routine before the harder subjects arrive.

Content overlap: Air Law, Operational Procedures
From ATPLSTUDY
Meteorology & Air Law Practice
Two subjects students underestimate
Met and Air Law look manageable on paper but have large question banks full of specific detail. Test where your gaps actually are before booking.
Try Met & Air Law Questions

Making the most of content overlaps

Several of the 13 subjects share significant content. Studying pairs of related subjects concurrently, rather than sequentially, allows you to cover the shared material once and apply it across both question banks. This is one of the most efficient techniques available in ATPL preparation.

The three most valuable pairings are AGK and Instrumentation, which share aircraft systems, sensors, and avionics content extensively; Performance and Principles of Flight, which share the aerodynamic foundations of lift, drag, and stall behaviour; and General Navigation and Flight Planning, which share calculation methods, the flight computer, and fuel-related navigation concepts. For each pairing, begin whichever subject has the larger or more demanding syllabus first, then introduce the paired subject once you have a working foundation in the first.

The most efficient study sequence

Phase 1: Communications, Mass and Balance, Human Performance. Phase 2: Air Law, Meteorology, Operational Procedures. Phase 3: AGK and Instrumentation together, Principles of Flight. Phase 4: General Navigation, Performance, Flight Planning, Radio Navigation. This sequence builds confidence early, exploits content overlaps, and reserves maximum time for the hardest subjects.

Frequently asked questions

Put the knowledge to work

6,000+ practice questions, free, no account needed

ATPLSTUDY covers all 13 ATPL subjects with EASA-aligned questions and full answer explanations. Start on whichever subject you are studying now.

Start Practising Free