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ATPL · illustrated course

ATPL performance course: 14 illustrated chapters

The ATPL performance course follows the syllabus in 14 chapters: 109 key points explained in a few paragraphs, often with a diagram, what to remember and, for many, the classic exam trap. The first chapter, « Regulatory framework and basic concepts », can be read in full on this page.

Read chapter 1The 834 questions of this subject

Contents

Each chapter explains, point by point, what the questions of the bank ask, with a « Remember » box and often the classic exam trap. The first chapter is free, below and in the app; the next ones are for ATPL subscribers.

  1. 1.Regulatory framework and basic concepts

    Free

    Certification and Air OPS, Classes A, B and C, gross and net performance, atmosphere, speeds and wind.

    7 key points · 64 questions of the bank

  2. 2.Flight mechanics relevant to performance

    Subscribers

    Balance of forces, drag and power curves, VMD and VMP, effects of mass, altitude, flaps and centre of gravity.

    10 key points · 145 questions of the bank

  3. 3.Take-off Speeds

    Subscribers

    Critical engine, VMCA, VMCG, VEF, V1, VR, VMU, VLOF, V2 and their regulatory relationships (CS-25).

    8 key points · 114 questions of the bank

  4. 4.Declared distances and required distances

    Subscribers

    TORA, TODA, ASDA, LDA, clearway and stopway, slope and pavement strength, TODR, TORR and ASDR in Class A.

    8 key points · 53 questions of the bank

  5. 5.Maximum take-off mass (Class A)

    Subscribers

    Runway, climb, obstacle, tyre and brake limitations, effects of parameters, balanced V1, stopways and clearways, flap selection and improved climb.

    9 key points · 198 questions of the bank

  6. 6.Take-off flight path and obstacles

    Subscribers

    Climb segments, minimum gradients, net flight path, take-off funnel (obstacle corridor), turns, acceleration height and noise abatement procedures.

    10 key points · 107 questions of the bank

  7. 7.Reduced-Thrust Take-off

    Subscribers

    Assumed temperature and derated thrust: principle, determination, conditions of use and prohibitions.

    5 key points · 13 questions of the bank

  8. 8.Wet and Contaminated Runways

    Subscribers

    Definitions, RWYCC, precipitation drag, effects on take-off and stopping, aquaplaning, anti-skid and spoilers.

    7 key points · 41 questions of the bank

  9. 9.Climb Performance

    Subscribers

    Climb gradient and rate of climb, Vx and Vy, effects of mass, altitude, flaps and wind, IAS/Mach climb and ceilings.

    9 key points · 153 questions of the bank

  10. 10.Cruise: range, endurance, optimum altitude

    Subscribers

    Specific range, maximum range and endurance speeds, wind, LRC, cost index, optimum altitude, buffet and limitations.

    10 key points · 152 questions of the bank

  11. 11.Descent and Gliding

    Subscribers

    Equilibrium in descent, glide angle and lift-to-drag ratio, effects of mass and wind, rate of descent, descent at constant Mach then constant IAS.

    6 key points · 42 questions of the bank

  12. 12.Engine Failure in Cruise: Drift-down

    Subscribers

    Drift-down procedure, gross and net flight paths, obstacle clearance requirements, fuel jettisoning, ETOPS and Class B rules.

    7 key points · 30 questions of the bank

  13. 13.Landing (Class A)

    Subscribers

    Landing distance, VREF, regulatory factors for dry, wet and contaminated runways, effects of parameters, go-around gradients and maximum landing mass.

    6 key points · 109 questions of the bank

  14. 14.Class B aeroplanes: take-off, climb, landing

    Subscribers

    Regulatory take-off and landing factors, surfaces and slopes, obstacle clearance with cloud base, and reading the CAP 698 charts.

    7 key points · 68 questions of the bank

Chapter 1: Regulatory framework and basic concepts

Certification and Air OPS, Classes A, B and C, gross and net performance, atmosphere, speeds and wind.

Two complementary sets of regulations

← Faites glisser le schéma →

Certification (CS-23, CS-25, flight manual) and operations (Air OPS, operations manual)

© ForAllPilots

The performance of a transport aeroplane is governed by two families of texts:

  • certification (EASA CS-25 for large aeroplanes, CS-23 for light and commuter aeroplanes): the manufacturer demonstrates the performance during flight tests and publishes it in the Aircraft Flight Manual (AFM);
  • operations: the European Air OPS regulation (EU 965/2012), Part-CAT, Subpart POL. From it, the operator produces its Operations Manual (OM): charts, RTOM tables, EFB software.

A flight is compliant only if both are respected: the aeroplane is able to do it (certification) and the operator has applied the regulatory margins (operations).

Remember

Manufacturer → AFM (CS-25/CS-23). Operator → operations manual (Air OPS, CAT.POL).

Exam trap

Older questions quote JAR-OPS 1 or EU-OPS: these texts have been replaced by Air OPS (EU Regulation 965/2012). In the exam, "JAR-OPS / EU-OPS" simply means the operations text.

Performance Classes A, B and C

← Faites glisser le schéma →

Table of performance classes by powerplant, seats and mass

© ForAllPilots

Air OPS places each commercial air transport aeroplane in a performance class, according to its powerplant, its maximum certified take-off mass (MTOM) and its maximum operational passenger seating configuration (MOPSC):

  • Class A: all multi-engine jets, and turboprops with more than 9 seats or more than 5,700 kg;
  • Class B: propeller-driven aeroplanes with 9 seats or fewer and 5,700 kg or less;
  • Class C: aeroplanes with piston engines and more than 9 seats or more than 5,700 kg.

Class A is the most demanding (failure of the critical engine at any moment, contaminated runways addressed) but it allows operation in the widest range of conditions.

Remember

Class B: propellers, ≤ 9 seats AND ≤ 5,700 kg. Multi-engine jet = always Class A.

Exam trap

A 6-seat, 5,650 kg business twin-jet is Class A (jet), not Class B. According to Air OPS, a twin piston-engine "commuter" with more than 9 seats or more than 5,700 kg (up to 19 seats and 8,618 kg) falls under Class C; some exam manuals nevertheless place it in Class B, and a question "according to the text" expects that answer.

CS-23 categories: normal, utility, aerobatic

← Faites glisser le schéma →

CS-23 categories and their main limits

© ForAllPilots

A light aeroplane certified under CS-23 belongs to a category that sets its load factors and its use:

  • normal: non-aerobatic flight, bank angle limited to 60°, positive limit load factor up to 3.8 (a formula that decreases with mass);
  • utility: 4.4, limited aerobatics (spins if approved);
  • aerobatic: 6.0;
  • commuter: twin-engine aeroplanes up to 19 passengers and 8,618 kg, same limits as normal.

The normal, utility and aerobatic categories are limited to 9 passengers and 5,700 kg. A 2,100 kg aeroplane with n = +3.5 therefore belongs to the normal category.

Remember

Normal 3.8 g (60° max) — utility 4.4 g — aerobatic 6 g.

Exam trap

Since 2017, CS-23 has classified aeroplanes by seating and performance levels, but exam questions still use the historical categories.

Gross and net performance

← Faites glisser le schéma →

Distribution of fleet performance: gross = average, net = gross minus a margin

© ForAllPilots

Certification tests give measured performance on new aeroplanes flown by test pilots. From this, the manufacturer derives the gross performance: the average performance that a well-maintained fleet, operated according to the manual's procedures, should achieve.

By definition, half of the aeroplanes perform worse than the average. For commercial air transport, net performance is therefore used: gross performance degraded by a safety margin. The more probable the event, the larger the margin; for an extremely improbable event, it can be zero.

Example: on take-off, net gradient = gross gradient − 0.8 % (twin-engine aeroplane).

Remember

Gross = fleet average. Net = degraded gross (regulatory margins). Obstacles are calculated using net performance.

Hot, high and humid: density

← Faites glisser le schéma →

High temperature, altitude and humidity reduce air density

© ForAllPilots

Almost all performance depends on the air density ρ:

  • pressure altitude is the altitude read with the 1013.25 hPa setting;
  • density altitude is the pressure altitude corrected for the temperature deviation from ISA (in the standard atmosphere, the two are equal);
  • humidity also reduces ρ (water vapour is lighter than dry air).

When ρ decreases: for the same indicated airspeed the TAS increases (hence ground speed and distances), and the engine thrust or power decreases. Result: longer take-off and landing distances, lower gradients and rates of climb, lower ceilings.

Remember

ISA: 15 °C and 1013.25 hPa at sea level, −2 °C/1,000 ft, tropopause 36,090 ft at −56.5 °C.

Exam trap

Temperature is not the only factor: pressure matters too. A cold runway at high pressure is "good performance". Higher atmospheric pressure (high QNH) shortens the take-off and improves climb.

IAS, CAS, TAS and Mach

← Faites glisser le schéma →

Variation of TAS with altitude at constant CAS and at constant Mach

© ForAllPilots

  • IAS: airspeed indicator reading; CAS: IAS corrected for instrument and position errors. CAS measures the dynamic pressure (total pressure Pt − static pressure Ps).
  • TAS: actual speed relative to the air; TAS = EAS / √σ, and it increases with altitude at constant CAS.
  • Mach = TAS / a, with a = 39√T (kt, T in kelvins).

In a climb at constant CAS, TAS and Mach increase. At constant Mach, TAS decreases in the troposphere (the temperature falls) and remains constant above the tropopause. The stall speed is constant in IAS, but increases in TAS and in Mach with altitude.

Remember

Constant Mach: below the tropopause CAS ↓ and TAS ↓; above it CAS ↓ and TAS constant.

Wind components

← Faites glisser le schéma →

Resolution of a 20 kt wind at 50° to the runway axis

© ForAllPilots

The wind is resolved relative to the runway or track axis:

  • headwind / tailwind component = V × cos θ;
  • crosswind component = V × sin θ (θ = angle between the wind and the axis).

The longitudinal component is used in all performance calculations (take-off, landing, ground distances). The crosswind component does not enter into performance: it is a flight manual limitation (demonstrated crosswind, for example 0.2 VS0 for a CS-23 light aeroplane).

Example: runway 35, wind 300°/20 kt → θ = 50°, crosswind ≈ 15 kt. With VS0 = 70 kt, the demonstrated wind (14 kt) is exceeded.

Remember

Crosswind = V sin θ; headwind = V cos θ. sin 10° ≈ 0.17: 30 kt wind at 10° → 5 kt crosswind.

Exam trap

Crosswind changes neither the runway-limited mass nor the take-off speeds in regulatory calculations: it appears only as a limitation.

The course goes on with chapter 2, « Flight mechanics relevant to performance ». It is read in the Course tab of the app with a ATPL subscription, and each chapter ends with the questions of the bank about it. See pricing

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