Aircraft Performance - Complete ATPL Subject Guide

Aircraft Performance, officially designated as ATPL Subject 032, covers the factors affecting aircraft performance during all phases of flight. This subject focuses primarily on propeller-driven aircraft and general performance principles applicable to all aircraft types. Jet aircraft performance (Class A operations) is covered separately in Subject 034.

For professional pilots, performance knowledge is essential for safe flight planning, ensuring regulatory compliance, optimizing fuel efficiency, and making informed decisions about takeoff, climb, cruise, descent, and landing.

What is Aircraft Performance?

Aircraft Performance encompasses the study of:

• Performance fundamentals (forces, power, thrust, drag)
• Takeoff performance (distances, speeds, runway requirements)
• Climb performance (rate of climb, climb gradient, factors affecting climb)
• Cruise performance (range, endurance, cruise speeds)
• Descent performance (descent planning, drag devices)
• Landing performance (distances, approach speeds, factors)
• Performance factors (weight, altitude, temperature, wind, runway condition)
• Performance planning (using charts, calculations, regulations)

Subject 032 Exam Details

Number of Questions: 37 questions Exam Duration: 1 hour 30 minutes Pass Mark: 75% (28 correct answers) Difficulty Level: Medium-Hard (requires understanding of graphs, calculations, and applying concepts) Recommended Study Hours: 60-80 hours Prerequisites: Strong understanding of Principles of Flight (drag, lift, forces) and Mass & Balance highly beneficial

Performance is a demanding subject requiring ability to interpret graphs, perform calculations, and apply theoretical knowledge to practical scenarios.

Performance Fundamentals

Forces in Flight

Aircraft performance is fundamentally determined by the balance of forces acting on the aircraft:

Four Forces:

• Lift (L): Generated by wings, opposes weight
• Weight (W): Gravitational force, acts downward
• Thrust (T): Produced by engines (propeller or jet), provides forward force
• Drag (D): Air resistance, opposes thrust

• Straight and level flight: Lift = Weight, Thrust = Drag
• Steady climb: Thrust > Drag, excess thrust pulls aircraft upward
• Steady descent: Thrust < Drag (or idle thrust), gravity pulls aircraft downward

Power and Thrust

Thrust:

• Force produced by engine/propeller system
• Measured in Newtons (N) or pounds-force (lbf)

• Rate of doing work = Force × Velocity
• Power (P) = Thrust (T) × Velocity (V)
• Measured in Watts (W), kilowatts (kW), or horsepower (HP)
• 1 HP = 746 W

• Maximum power or thrust engine can produce at given conditions
• Propeller aircraft: Power available relatively constant with speed
• Jet aircraft: Thrust available relatively constant, power available increases with speed

• Power needed to overcome drag at given speed
• P_R = Drag × Velocity
• Varies with speed: high at low speeds (high induced drag), high at high speeds (high parasite drag), minimum at intermediate speed

• Thrust engine can produce

• Thrust needed to balance drag in level flight
• T_R = Drag

Drag Review

Understanding drag is fundamental to performance:

Total Drag = Parasite Drag + Induced Drag

• Speed at which total drag is lowest
• Occurs where parasite drag = induced drag
• Best endurance speed for jets (minimum fuel flow per hour)
• Best glide speed (maximum L/D ratio)

• Speed at which lift-to-drag ratio is maximum
• Same as V_MD
• Best range speed for jets (maximum distance per unit fuel)
• Best glide range (maximum glide distance)

Power Curves

Power Required Curve:

• Graph of power required vs. airspeed
• U-shaped curve, minimum power required at V_MP (minimum power speed)

• Horizontal line (propeller aircraft, approximately constant)
• Excess power = Power available - Power required
• Maximum excess power occurs at VMP → Best rate of climb speed (VY)

Takeoff Performance

Takeoff performance determines whether an aircraft can safely depart from a given runway under prevailing conditions.

Takeoff Distances and Speeds

Takeoff Phases:

1. Ground roll: From brake release to liftoff
2. Airborne distance: From liftoff to screen height (50 ft / 15 m for single/multi-engine propeller, 35 ft / 10.7 m for jets)
3. Total takeoff distance: Ground roll + airborne distance to screen height

• VR ≥ 1.05 VMC (ensures control if engine fails at rotation)
• V2 ≥ 1.2 VS (adequate stall margin at screen height)

Factors Affecting Takeoff Performance

Weight:

• Increased weight → Longer takeoff distance
• Heavier aircraft requires higher liftoff speed
• Greater mass resists acceleration
• Approximately: 2× weight → 4× takeoff distance (squared relationship)

• Increased altitude → Longer takeoff distance
• Lower air density reduces:
• Engine power (less oxygen for combustion)
• Propeller thrust (less dense air to accelerate)
• Lift (require higher true airspeed to generate same lift)
• Approximately: +1,000 ft altitude → +10% takeoff distance

• Increased temperature → Longer takeoff distance
• Higher temperature reduces air density (similar to altitude effect)
• Density Altitude = Pressure Altitude + (120 × (OAT - ISA Temperature))
• Hot day at high altitude = very long takeoff distance
• Approximately: +10°C → +10% takeoff distance

• Headwind → Shorter takeoff distance (increases airspeed relative to ground speed)
• Approximately: 10 kt headwind → -20% takeoff distance
• Tailwind → Longer takeoff distance (decreases airspeed relative to ground speed)
• Approximately: 10 kt tailwind → +30-40% takeoff distance
• Tailwind has greater effect than headwind (asymmetrical)

• Upslope → Longer takeoff distance (component of weight opposes acceleration)
• Approximately: +1% upslope → +10% takeoff distance
• Downslope → Shorter takeoff distance (component of weight aids acceleration)
• Downslope takeoff may be prohibited (difficult to stop if rejected)

• Dry, paved → Normal takeoff distance (baseline)
• Wet → Slightly longer (reduced tire friction, possible hydroplaning)
• Contaminated (snow, slush, ice, standing water) → Significantly longer
• Slush and standing water add drag, reduce acceleration
• Performance charts often do not cover contaminated runways for propeller aircraft (prohibited or requires manufacturer data)

• High elevation = high pressure altitude, reduces performance
• Must ensure Takeoff Distance Available (TODA) ≥ Takeoff Distance Required (TODR)

Balanced Field Length (Multi-Engine Aircraft)

Balanced Field Length Concept:

• Runway length at which:
• Distance to accelerate to decision speed (V1), experience engine failure, and stop = Distance to accelerate to V1, experience engine failure, and continue takeoff to screen height
• V_1 (Decision Speed): Speed below which pilot must abort takeoff if engine fails; above which pilot must continue

• Distance from brake release to full stop after:
• Accelerate to V_1
• Engine failure at V_1
• Pilot recognition (1-2 seconds)
• Apply brakes, abort takeoff

• Distance from brake release to screen height after:
• Accelerate to V_1
• Engine failure at V_1
• Continue takeoff on remaining engine(s)
• Reach V_2 at screen height

• V_1 value where ASD = AGD
• Ensures adequate runway for either decision (abort or continue)

Takeoff Performance Planning

Regulatory Requirements:

• Must comply with aircraft Flight Manual and regulations (EASA Part-CAT, FAA Part 91/121/135)
• Factored distances (safety margins applied to demonstrated performance)

1. Determine pressure altitude, temperature, weight
2. Enter chart with these values
3. Apply corrections for wind, slope, runway condition
4. Determine takeoff distance required (TODR)
5. Compare TODR with Takeoff Distance Available (TODA)
6. If TODR > TODA, reduce weight, wait for better conditions, or choose longer runway

• Maximum weight at which takeoff distance requirement can be met
• Often limits actual takeoff weight (in addition to structural MTOW)

Climb Performance

Climb performance determines how quickly and efficiently an aircraft can gain altitude.

Climb Parameters

Rate of Climb (ROC):

• Vertical speed, altitude gain per unit time
• Measured in feet per minute (fpm) or meters per second (m/s)
• ROC = Excess Power / Weight (propeller aircraft)
• ROC = (Excess Thrust × Velocity) / Weight (jet aircraft)

• Ratio of altitude gain to horizontal distance
• Expressed as percentage: Gradient (%) = (Altitude gain / Distance) × 100
• Also expressed as ratio (e.g., 1:20 means 1 ft altitude gain per 20 ft horizontal distance)
• Climb Gradient (%) = (ROC / Groundspeed) × 100
• Example: ROC = 500 fpm, GS = 6,000 ft/min (100 kt = 6,000 ft/min) → Gradient = (500/6,000)×100 = 8.3%

• Angle between flight path and horizontal
• Climb Angle (°) = arctan(Gradient)
• Example: 10% gradient ≈ 5.7° climb angle

Best Climb Speeds

V_Y (Best Rate of Climb Speed):

• Speed at which rate of climb is maximum
• Maximizes altitude gain per unit time
• Occurs at speed of maximum excess power (propeller) or maximum (TA - TR) × V (jet)
• Use when: Climb to cruise altitude as quickly as possible, terrain clearance with time available

• Speed at which climb gradient (angle) is maximum
• Maximizes altitude gain per unit distance
• Occurs at speed of maximum excess thrust (Thrust available - Thrust required)
• Use when: Obstacle clearance immediately after takeoff, short distance to clear obstacle
• VX < VY (slower speed)

Factors Affecting Climb Performance

Weight:

• Increased weight → Reduced rate of climb and climb gradient
• Heavier aircraft requires more power/thrust to maintain level flight, less excess for climb
• Approximately: +10% weight → -20% ROC

• Increased altitude → Reduced rate of climb
• Engine power decreases with altitude (less oxygen)
• True airspeed increases for same indicated airspeed (less drag per kt TAS, but less power available)
• Absolute ceiling: Altitude at which ROC = 0 (cannot climb higher)
• Service ceiling: Altitude at which ROC = 100 fpm (practical maximum operating altitude for propeller aircraft)

• Increased temperature → Reduced rate of climb
• Higher temperature reduces air density, decreases engine power
• Hot day → lower service ceiling

• Headwind → Steeper climb gradient (same ROC, lower groundspeed)
• Tailwind → Shallower climb gradient (same ROC, higher groundspeed)
• ROC unaffected by wind (vertical component), but gradient affected

• Flaps extended → Reduced climb performance (increased drag)
• Landing gear extended → Significantly reduced climb performance (high drag)
• Retract gear and flaps as soon as safely possible after takeoff

Climb Planning

Normal Climb:

• Climb at V_Y for best time to altitude
• Adjust power for climb power setting (manufacturer recommendation)
• Monitor engine temperatures (CHT, EGT)

• Climb at V_X until obstacle cleared
• Transition to V_Y for continued climb

• Maintain constant airspeed or Mach number, allow altitude to increase gradually
• More fuel-efficient for jets, often used on long flights

• Multi-engine aircraft after engine failure
• May not maintain altitude, gradually descend to lower altitude where can maintain level flight on remaining engine(s)
• Drift-down charts show altitude loss vs. distance

Cruise Performance

Cruise performance focuses on maximizing range or endurance while maintaining efficient operation.

Range and Endurance

Range:

• Maximum distance aircraft can fly on given fuel
• Specific Range (SR): Distance per unit fuel = Nautical miles per kg (or per gallon)
• SR = Groundspeed / Fuel Flow
• Maximize range: Fly at speed with maximum SR

• Maximum time aircraft can remain airborne on given fuel
• Specific Endurance: Time per unit fuel = Hours per kg
• Endurance = Time airborne / Fuel consumed
• Maximize endurance: Fly at speed with minimum fuel flow

Best Range and Endurance Speeds

Propeller Aircraft:

Jet Aircraft:

Factors Affecting Range and Endurance

Weight:

• Increased weight → Reduced range and endurance
• Heavier aircraft requires higher lift → higher AOA or faster speed → higher drag → more fuel burn
• As fuel burns during flight, weight decreases, performance improves

• Propeller aircraft:
• Best range altitude: Moderate altitude where engine efficiency and drag balance optimally
• Too low: High drag (dense air)
• Too high: Engine power decreases significantly
• Jet aircraft:
• Best range altitude: High altitude (lower drag, efficient engine operation in thin air)
• Cruise climb common: Altitude increases as weight decreases during flight

• Headwind → Reduced range (groundspeed decreases), endurance unchanged
• Tailwind → Increased range (groundspeed increases), endurance unchanged
• Adjust cruise speed for wind:
• Headwind: Fly slightly faster than best range speed (minimize time in headwind)
• Tailwind: Fly slightly slower (maximize time in tailwind)

• Non-standard temperature affects air density, engine performance
• Cold day: Denser air, more drag but more engine power
• Hot day: Less dense air, less drag but less engine power

Cruise Speed Selection

Long Range Cruise (LRC):

• ~99% of maximum range at slightly higher speed
• Trade 1% range for ~5% higher speed (saves time with minimal fuel penalty)
• Common choice for airlines

• Fly at V_MD for maximum distance per fuel
• Slower, maximum fuel efficiency

• Faster than LRC, reduced range
• Used when time more critical than fuel

• Balance of fuel efficiency and speed
• Varies by operator preference

Power Settings and Leaning

Propeller Aircraft Power Management:

• Cruise power: Typically 65-75% of maximum continuous power
• Mixture leaning: Adjust fuel-air mixture for altitude
• Rich mixture: Good cooling, lower fuel efficiency, more power
• Lean mixture: Better fuel efficiency, higher temperatures, slightly less power
• Lean for cruise: Best fuel economy (follow manufacturer procedures)
• Full rich for takeoff and landing: Ensure adequate cooling and power

• Lean until EGT peaks (stoichiometric mixture)
• Then enrich slightly (50°F below peak EGT typical) for safety margin
• Some engines: Lean to specific fuel flow or EGT value per manufacturer

Descent Performance

Descent planning ensures safe and efficient transition from cruise to approach.

Descent Planning

Descent Rate:

• Vertical speed during descent (fpm)
• Selected based on desired descent gradient, groundspeed

• Typically 3° for ILS approach (300 ft per NM)
• Rule of thumb: Descent rate (fpm) = Groundspeed (kts) × 5
• Example: GS = 120 kts → ROD = 600 fpm for 3° descent

• Distance to descend (NM) = Altitude to lose (ft) / 300 (for 3° descent)
• Example: Cruise at FL100 (10,000 ft), destination elevation sea level → Distance = 10,000 / 300 ≈ 33 NM
• Start descent 33 NM from destination

• Altitude to lose (thousands of ft) × 3 = Distance (NM)
• Example: 10,000 ft to lose → 10 × 3 = 30 NM

Drag Devices

Speedbrakes / Spoilers:

• Increase drag without increasing speed
• Allow steeper descent or faster deceleration
• Retract before landing (some aircraft auto-retract on approach)

• Extending gear significantly increases drag
• Used to steepen descent or slow down
• Gear down speed (VLO or VLE) must not be exceeded

• Increase drag and lift
• Allow slower approach speed
• Deployed in stages during approach

Descent Speed Management

Maximum descent speed:

• Limited by structural considerations (VMO/MMO)
• May be limited by ATC or noise abatement procedures

• Maintain reasonable speed (250 kts below 10,000 ft in most airspace)
• Configure progressively for approach (flaps, gear)

• Rapid descent (e.g., depressurization)
• Maximum safe speed, speedbrakes deployed, steep descent rate

Landing Performance

Landing performance determines whether an aircraft can safely land on a given runway.

Landing Distances and Speeds

Landing Phases:

1. Air distance: From screen height (50 ft) to touchdown
2. Ground roll: From touchdown to full stop
3. Total landing distance: Air distance + ground roll

• Base speed: VREF (1.3 × VS)
• Gust correction: Add half of gust factor (e.g., wind 15G25, add 5 kts)
• Maximum correction: Typically +10-15 kts above V_REF
• Excess speed increases landing distance significantly

Factors Affecting Landing Performance

Weight:

• Increased weight → Longer landing distance
• Heavier aircraft requires higher approach speed (VREF based on VS, which increases with weight)
• Approximately: +10% weight → +20% landing distance

• Increased altitude → Longer landing distance
• Higher true airspeed for same indicated airspeed
• Reduced air density → less effective brakes (less drag, less propeller braking)
• Approximately: +1,000 ft altitude → +5% landing distance

• Increased temperature → Longer landing distance (reduced air density)

• Headwind → Shorter landing distance (lower groundspeed at touchdown)
• Approximately: 10 kt headwind → -20% landing distance
• Tailwind → Longer landing distance (higher groundspeed at touchdown)
• Approximately: 10 kt tailwind → +40% landing distance
• Tailwind landing avoided if possible (regulations often limit tailwind component to 10 kts)

• Upslope → Shorter landing distance (component of weight aids deceleration)
• Downslope → Longer landing distance (component of weight opposes deceleration)
• Approximately: +1% downslope → +10% landing distance

• Dry, paved → Normal landing distance (baseline)
• Wet → Longer distance (reduced braking friction, possible hydroplaning)
• Approximately: +15-30% landing distance
• Contaminated (snow, slush, ice) → Significantly longer
• May double or triple landing distance
• Performance data may not be available for contaminated runways (pilot judgment required)

• Stabilized approach: Proper speed, descent rate, configuration → Normal landing distance
• Steep approach: Higher descent rate → Longer flare, longer landing distance
• High speed on approach: Excess speed bleeds off during flare → Significantly longer landing distance
• 10 kts excess speed → ~20% longer landing distance

Landing Performance Planning

Regulatory Requirements:

• Landing distance required (LDR) must be less than Landing Distance Available (LDA)
• Dry runway factor: LDR × 1.67 ≤ LDA (approximately 60% of runway length available)
• Wet runway factor: Additional margin required (varies by regulation)

1. Determine pressure altitude, temperature, weight
2. Enter chart with these values
3. Apply corrections for wind, slope, runway condition
4. Determine landing distance required (LDR)
5. Apply safety factor (1.67 for dry runway)
6. Compare factored LDR with Landing Distance Available (LDA)
7. If factored LDR > LDA, reduce weight, divert to longer runway, or wait for better conditions

• Maximum weight at which landing distance requirement can be met
• May require fuel burn, fuel jettison, or diversion if landing weight will exceed limit

Stopping Performance

Wheel Brakes:

• Primary means of deceleration after touchdown
• Effectiveness depends on:
• Brake system condition
• Tire condition and pressure
• Runway surface friction
• Weight on wheels (more weight = better braking)

• Propeller aircraft: Propeller provides some drag
• Jets: Reverse thrust significantly reduces ground roll

• Deployed on landing to reduce lift ("dump lift"), increase weight on wheels
• Improves brake effectiveness

• Redirects engine exhaust forward
• Highly effective at high speeds, less effective below ~60 kts
• Not credited in certified landing distance (but used in practice)

Performance Planning and Regulations

Regulatory Framework

EASA and FAA Regulations:

• Part-CAT (Commercial Air Transport): Strict performance requirements, factored distances
• Part-NCO (Non-Commercial Operations): Less stringent, but still must comply with AFM
• Light aircraft / General Aviation: Follow AFM/POH performance charts

• CS-23 (EASA) / Part 23 (FAA): Normal, utility, aerobatic, and commuter aircraft
• CS-25 (EASA) / Part 25 (FAA): Large transport aircraft
• Performance demonstrated during certification, published in AFM

Using Performance Charts and Tables

Types of Performance Charts:

• Tabular: Data in table format, interpolation required
• Graphical: Data on graphs, read values from curves
• Nomographs: Multiple scales connected by reference lines

1. Identify chart type: Takeoff, landing, climb, cruise, etc.
2. Determine required inputs: Weight, altitude, temperature, wind, etc.
3. Enter chart: Follow instructions (may require multiple steps)
4. Interpolate: If conditions between tabulated values, interpolate linearly
5. Apply corrections: Wind, slope, surface condition
6. Apply safety factors: Regulatory factors (e.g., 1.67 for landing)
7. Compare with available distance/performance

• Linear interpolation: Assume values change linearly between tabulated points
• Formula: Value = Value1 + [(Value2 - Value1) × (Input - Input1) / (Input2 - Input1)]

• Misreading scales: Check units (ft vs. meters, °C vs. °F, kg vs. lbs)
• Wrong chart: Ensure using correct chart for conditions (e.g., flap setting, runway surface)
• Forgetting corrections: Must apply all applicable corrections (wind, slope, etc.)
• Arithmetic mistakes: Double-check calculations, especially under pressure

Operational Considerations

Balanced Field Considerations:

• Critical for multi-engine aircraft departing from short runways
• Ensure adequate runway length for both accelerate-stop and accelerate-go scenarios

• Obstacle clearance: Must achieve specified climb gradient to clear obstacles
• Departure procedures (SID) may specify minimum climb gradients
• Reduced climb performance (high weight, high altitude, high temperature, engine out) may prevent departure

• Structural limits (MTOW, MLW, MZFW)
• Performance limits (takeoff distance, landing distance, climb gradient)
• Limiting weight: Minimum of all applicable limits

• Wind (headwind/tailwind components, gusts)
• Temperature (hot day → reduced performance)
• Pressure altitude (altimeter setting, elevation)
• Runway condition (dry, wet, contaminated)
• Visibility (affects approach and landing minima, not directly performance but operational limit)

• Conservative planning: Use worst-case reasonable assumptions
• Margin: Don't plan to use 100% of available runway
• Alternatives: Have backup plan (divert, delay departure, reduce weight)
• Go/No-Go Decision: Be prepared to cancel or delay flight if performance marginal

EASA Learning Objectives - Subject 032

According to the EASA ATPL syllabus, candidates must demonstrate knowledge of:

Performance Fundamentals

• Forces in flight: Lift, weight, thrust, drag, and their balance
• Power and thrust: Definitions, power required vs. available, thrust required vs. available
• Drag: Parasite and induced drag, total drag curve, minimum drag speed (VMD, L/Dmax)
• Power curves: Power required curve, minimum power speed (V_MP)

Takeoff Performance

• Takeoff distances: Ground roll, airborne distance, total takeoff distance, screen height
• Takeoff speeds: VR, VLOF, V2, VMC, V_S
• Factors affecting takeoff: Weight, altitude, temperature, wind, slope, surface condition
• Balanced field length: V_1, accelerate-stop distance, accelerate-go distance
• Takeoff performance planning: Using charts, regulatory requirements, performance-limited weight

Climb Performance

• Rate of climb and climb gradient: Definitions, calculations, relationship to excess power/thrust
• Best climb speeds: VX (best angle), VY (best rate), use cases
• Factors affecting climb: Weight, altitude, temperature, wind, configuration
• Ceilings: Absolute ceiling, service ceiling
• Climb planning: Normal climb, obstacle clearance, cruise climb

Cruise Performance

• Range and endurance: Definitions, specific range, specific endurance
• Best range and endurance speeds: Propeller vs. jet aircraft
• Factors affecting range/endurance: Weight, altitude, wind, temperature
• Cruise speed selection: LRC, MRC, high-speed cruise, economy cruise
• Power settings and leaning (propeller aircraft)

Descent Performance

• Descent planning: TOD calculation, descent rate, descent gradient
• Drag devices: Speedbrakes, spoilers, landing gear, flaps
• Descent speed management

Landing Performance

• Landing distances: Air distance, ground roll, total landing distance
• Landing speeds: VREF, VAPP, VAT, VTD
• Factors affecting landing: Weight, altitude, temperature, wind, slope, surface condition, approach profile
• Landing performance planning: Using charts, regulatory factors, performance-limited landing weight
• Stopping performance: Brakes, aerodynamic braking, reverse thrust

Performance Planning

• Regulations: EASA Part-CAT, certification standards (CS-23, CS-25)
• Performance charts: Types, interpretation, interpolation
• Operational considerations: Balanced field, climb gradients, limiting weights, weather, risk management

Exam Tips & Common Questions

Memory Aids

Four Forces in Flight:

• "Lift opposes Weight, Thrust opposes Drag"

• "VX for maXimum angle (obstacle clearance), VY for Yank (pull up fast, best rate)"

• "Best Range = VMD (Minimum Drag), Best Endurance = VMP (Minimum Power)"
• "VMP < VMD" (minimum power slower than minimum drag)

• "High, Hot, Heavy → Long takeoff distance"
• Increased altitude, temperature, weight all increase takeoff distance

• "Headwind helps (shorter distance), Tailwind hurts (longer distance)"
• "Tailwind effect > Headwind effect" (asymmetric)

• "10 kts extra speed → 20% longer landing distance"

High-Yield Topics

Based on historical exam analysis, these topics appear frequently:

1. Forces, power, and drag (10-15% of questions)

• Power required vs. available curves
• Minimum drag speed (VMD), minimum power speed (VMP)
• Excess power and climb performance

1. Takeoff performance calculations (20-25% of questions)

• Using takeoff charts
• Factors affecting takeoff distance (weight, altitude, temperature, wind, slope)
• Balanced field length, V_1 concept

1. Climb performance (15-20% of questions)

• VX vs. VY (best angle vs. best rate)
• Rate of climb and climb gradient calculations
• Factors affecting climb (weight, altitude, temperature, configuration)

1. Range and endurance (10-15% of questions)

• Best range and endurance speeds (propeller vs. jet)
• Factors affecting range/endurance (weight, altitude, wind)

1. Landing performance calculations (15-20% of questions)

• Using landing charts
• Factors affecting landing distance (weight, altitude, temperature, wind, surface)
• Approach speed and its effect on landing distance

1. Performance factors and graphs (15-20% of questions)

• Interpreting performance charts and graphs
• Interpolation
• Applying corrections and safety factors

Common Mistakes to Avoid

• Confusing VX and VY: Remember VX is slower, for obstacle clearance (angle); VY is faster, for best rate (time efficiency)
• Forgetting wind correction direction: Headwind reduces distance, tailwind increases distance
• Misreading chart scales: Always check units and scale carefully
• Forgetting to apply safety factors: Landing distance must include regulatory factor (e.g., ×1.67)
• Ignoring interpolation: If conditions between tabulated values, must interpolate
• Mixing up propeller and jet best speeds: Propeller best endurance at VMP; jet best endurance at ~1.32 × VMD

Tricky Question Types

Multi-Factor Performance:

• "What is takeoff distance for aircraft at 3,000 ft pressure altitude, 30°C, 10 kt tailwind, 2% upslope?"
• Approach: Start with baseline distance (chart), apply each correction sequentially or cumulatively as specified

• "Aircraft climbs at 500 fpm with groundspeed 100 kts. What is climb gradient?"
• Answer: Gradient (%) = (ROC / GS) × 100 = (500 / 6,000) × 100 = 8.3%
• Note: 100 kts = 100 NM/hr = 6,000 NM/60 min = 100 NM/min = 100 × 6,076 ft/min ≈ 6,000 ft/min (approximation for calculation)

• "What is best glide speed for maximum glide range?"
• Answer: VMD (L/Dmax), speed of minimum drag

• "Landing at 10 kts above V_REF increases landing distance by approximately how much?"
• Answer: ~20% longer

• "At balanced field length, accelerate-stop distance _ accelerate-go distance."
• Answer: Equals

Practical Application for Pilots

Pre-Flight Performance Planning

Takeoff Planning:

• Calculate takeoff distance required using AFM charts
• Check against runway length available
• Determine performance-limited takeoff weight if necessary
• Verify obstacle clearance requirements met
• Brief rejected takeoff procedure and V_1 (if applicable)

• Plan climb speed (VY for normal climb, VX if obstacle clearance needed)
• Calculate expected climb performance (time, fuel, distance)
• Brief emergency return procedure if applicable

• Select cruise altitude and speed (consider winds, fuel efficiency)
• Calculate range and endurance
• Plan fuel reserves

• Calculate top of descent
• Plan descent speed and configuration changes
• Calculate approach speed (V_REF + corrections)

• Calculate landing distance required using AFM charts
• Check against runway length available
• Determine performance-limited landing weight if necessary
• Plan go-around if landing performance marginal

In-Flight Performance Management

Monitoring:

• Compare actual performance (climb rate, fuel burn, groundspeed) with planned
• Adjust plan if actual differs significantly from expected

• If performance worse than expected (e.g., low climb rate), consider:
• Reduce weight (jettison fuel if available, return to departure airport)
• Change route (avoid high terrain)
• Divert to airport with better performance margin

• Reduced climb performance, may not maintain altitude
• Drift down to lower altitude if necessary
• Divert to nearest suitable airport

Performance-Related Incidents

Real-World Examples:

• Takeoff overrun: Inadequate takeoff performance planning (high weight, hot day, short runway, tailwind)
• Controlled flight into terrain (CFIT): Insufficient climb performance to clear terrain (high weight, high altitude, engine failure)
• Landing overrun: Excessive approach speed, tailwind landing, wet/contaminated runway, pilot continued approach despite unstabilized conditions

• Always perform thorough performance calculations
• Use conservative assumptions
• Brief rejected takeoff and go-around procedures
• Be prepared to delay departure or divert if performance marginal
• Stabilized approach criteria: If not stabilized by 500 ft AGL, go around

Study Strategy for Performance

Recommended Study Sequence

1. Performance fundamentals (1 week)

• Forces, power, thrust, drag
• Power curves, VMP, VMD

1. Takeoff performance (1-2 weeks)

• Takeoff distances, speeds
• Factors affecting takeoff
• Balanced field length
• Chart interpretation and calculations

1. Climb performance (1 week)

• ROC, gradient, VX, VY
• Factors affecting climb
• Ceilings

1. Cruise performance (1 week)

• Range, endurance, best speeds
• Factors affecting range/endurance

1. Descent and landing performance (1-2 weeks)

• Descent planning
• Landing distances, speeds
• Factors affecting landing
• Chart interpretation and calculations

1. Practice exams (1 week)

• Work full-length practice exams
• Focus on chart interpretation and multi-step calculations

Study Resources

• EASA Syllabus: Review official learning objectives
• Textbooks: CAE Oxford, Bristol Ground School, ATPL Ground Training
• Aircraft Flight Manuals (AFM/POH): Real performance charts (Cessna, Piper, Beechcraft for propeller; Boeing/Airbus for jets covered in Subject 034)
• Question banks: Aviationexam, Bristol GS, ATPL Ground Training (practice chart interpretation)
• Flight Simulator: Practice performance planning (takeoff, climb, cruise, descent, landing)

Study Tips

• Master the fundamentals first: Understand forces, power, drag before tackling performance calculations
• Practice chart interpretation: Work through many examples until comfortable
• Learn to interpolate: Essential skill for exam and real-world use
• Memorize key concepts: VX vs. VY, range vs. endurance speeds, performance factor effects
• Use systematic approach: Organize work, show all steps, check units
• Time management: Exam is 1.5 hours for 37 questions, ~2.4 minutes per question; practice working efficiently
• Draw diagrams: Visualize scenarios (aircraft climbing, forces, etc.) to aid understanding

Integration with Other Subjects

Performance connects with several other ATPL subjects:

• Principles of Flight: Drag, lift, forces—foundation for performance
• Mass & Balance: Weight affects all aspects of performance
• Meteorology: Wind, temperature, pressure altitude all affect performance
• Flight Planning: Performance data used for flight planning
• Performance Class A: Jet aircraft performance (separate subject, builds on Subject 032 concepts)
• Operational Procedures: Performance planning integrated into flight operations

Conclusion

Aircraft Performance is a demanding but highly practical subject. Every flight requires performance planning: Will the aircraft clear the runway and obstacles on takeoff? Can it climb to cruise altitude? Will it land safely on the available runway? Understanding performance is not just about passing an exam—it's about ensuring safe and efficient flight operations throughout your career.

The key to success in Performance is understanding the principles (forces, power, drag) and practicing calculations (using charts, interpolating, applying corrections). Master VX and VY concepts, understand how weight/altitude/temperature affect performance, and become proficient at reading performance charts.

Performance questions often involve multi-step calculations with charts and graphs. Practice these systematically: identify inputs, enter chart, interpolate, apply corrections, check answer reasonableness. Develop speed and accuracy through repeated practice.

Finally, always remember the practical application. Performance planning is not optional—it's a regulatory requirement and a safety necessity. Conservative planning with adequate margins can mean the difference between a safe flight and an accident.

Related Articles:

• Performance Class A (Jets) - ATPL Subject 034
• Mass & Balance - ATPL Subject 031
• Principles of Flight - ATPL Subject 081
• Flight Planning - ATPL Subject 033
• Meteorology - ATPL Subject 050
• Operational Procedures - ATPL Subject 070

• Review EASA Learning Objectives thoroughly
• Practice interpreting performance charts and graphs
• Master VX and VY concepts and use cases
• Work through takeoff and landing distance calculations
• Begin practicing with Performance question banks