Performance Final

Performance Calculations

to know Weight and Calculate Profit from payload

Payload

Weight of Pax, Baggage, & Cargo.

Basic Parameters affecting aircraft's performance

Temperature
Altitude
Speed

Temprature benefits in aviation

Performance Calculations.
Determining Icing Conditions.
Airspeed and Altitude Correction,
for Obtaining True Calculations

Ram Rise

increase Temperature due to
Compressibility.

Starting from 0.3 Mach speed

Static Air Temprature (SAT) (or) Outside Air Temprature (OAT)

temperature of

Free moving, Undisturbed Air Around an aircraft

corrected for Instrument & Compressibility Errors

Total Air Temprature (TAT)

“SAT”+ 100% of Ram Rise
obtained by TAT Probes

Ram Air Temperature (RAT)

SAT + Specific % of Ram Rise.

Altitude

Elevation with respect to an assumed reference level

Barometric Altitude

reduction in air pressure with an increase in altitude

QFE (Height)

Altimeter setting that indicates height Above Ground Level (AGL)

Absolute Altitude

Height AGL
Measured by RA

not exceeding 2500 feet

QNH ‘Local Altimeter Settings’

Altimeter setting used Below Transition Layer
when aircraft's fly with reference to

Mean Sea Level
Indicating Elevation, Provided by ATC

Indecated Altitude

Altitude on the altimeter when set to QNH
indicates the aircraft height above MSL

Transition Altitude

Highest available to use below the transition layer.
where transition from QNH To QNE

if Climbing should begin

Transition Layer

1000ft layer between

transition altitude & level

ensuring Vertical Separation of aircraft

Operating on Different Altimeter Settings

Transition Level

Lowest available for use Above the transition Layer.
where transition from QNE to QNH

if Descending should begin

QNE

Altimeter setting used Above Transition Layer
when aircraft have to fly with reference to Flight Level
@ Standard Pressure 1013.25Hpa

and “Pressure Altitude”

Pressure Altitude

Altitude on the altimeter when set to QNE
@ISA
which is 1013.25 hectopascals (hPa)
or 29.92 inches of mercury (inHg).

Density Altitude

Pressure altitude corrected for non-standard Temp.

used for (Perf. Calculations)
DA=[Non stndr temp. - 15°c] x120+PA

True Altitude

Actual Height of an object above Sea Level
not indicated by any instruments.

in ISA conditions, MSL = SL, so True Alt.= Indecatied Alt.

Takeoff speeds

V1, VR, V2, VMU, VMCG, VMCA

Safety key element for takeoff,

Enabling Pilot’s:

Situational awareness &

Decision-making in this

very dynamic stage.

misuse of takeoff speeds can lead to;

Tail strikes, High-speed Rejected takeoffs

Vs

Stall speed @ which airflow Separation Begins,
but Not Full wing stalls for ailerons to Stay Effective.
Highest point in the 'CL and AoA curve.'

VS1G

Stall speed at 1g load factor where Airflow

Separates Completely & Wing fully stalls.

VMCG

Minimum Control speed on Ground

at which aircraft still Controllable using Maximum Rudder Deflection only.
in case of 😞 engine failure & Other engine on T/O Thrust

Increase by

(high, high)—>Temp., Alt.

VMCA

Minimum Control speed in Air (Flight)

at which aircraft still Controllable using Maximum Ailerons Deflection only.
in case of 😞 engine failure & Other engine on T/O Thrust

VMU

Minimum unstick speed.
Lowest speed where aircraft can safely be Airborne
Without Encountering Tail Strike.

• Used during Certification Testing,

• Not Published in most Flight Manuals.

V lof

speed at which the airplane lifts off. depends on:
Weight,
(AoA) angle of attack,
Configurations.

Must always be Below

Maximum Tire Speed.

Maximum Tire Speed

Strength of the tires determines this speed due to the Exposure to

⬆Centrifugal forces @⬆Speeds

✈ Why it matters more at high-elevation airports:

• As Altitude ⬆, Density↓

• To generate same lift higher True Airspeed (TAS) is needed.

• Indicated airspeed (IAS) might be normal, But TAS may exceed the tire limit

VMBE

Maximum Break Energy Speed for

Full Braking to a Complete Stop, within Braking System's Heat Limitations
Depending on

1. Temperature,

2. Pressure,

3. Weight,

4. Runway Slope

5. Wind.

V1

Reference speed, whether you

Reject or Continue the takeoff.
Not a Decision but Action speed,
where the 1st Braking Action must be Applied in case of aborted T/O
therefore decision to reject takeoff must be taken before V1.
Minimum VMCG
Maximum VR & VMBE

VEF

Speed @ which critical engine is assumed to Fail. was 1 second,
now 2 seconds before Action speed (V1)
to allow pilots to react to
😞engine failure.

VR

Speed at which the airplane is rotated for liftoff.
Minimum (Lower limit) V1, & 1.05 VMCA

V2

Take Off Climb Speed
Reached @ Screen Height
& Maintained for the entire climb with takeoff Flaps,
in an 😞engine failure at or after V1.
Minimums (Lower limits) are:
1.1Vmca,

1.2 Vs,

1.13Vs1g

Screen Height

35ft for dry,

15 for wet runways,
above the takeoff surface after an engine failure at V1,
at which V2 speed must be reached.

Take off Preformance

Determining 3 things during this initial phase:

1. Capabilities and Limitations of aircraft
   

2. Minimum Runway Length Required for Safe Takeoffs,
   

3. Best Fuel Consumption
   which

   -Ensuring passenger safety

   -Reducing Wear on aircraft
   -Optimizing flight schedules.
   

Crtical Engine

in ↔Multi-engine aircraft with the Most Adverse Effects
on aircraft's Handling and Performance⚙️
in case of its 😞Failure.

TODR

Take-off Distance Required
Horizontal distance starting from;

Ground Roll until reaching 35 feet above take-off surface in case of 😞Engine Failure @V1

with all engines operating, 115% of horizontal distance, starting from ground roll to the screen height,

ASDR

-Accelerate Stop Distance Required
Sum of the Distances required to:
1) Accelerate with All Engines
2) Decelerate to a Full Stop

In Case of EF @ V1

TORA

Takeoff Runway Available Length

TORR

Take-Off Run Required
Horizontal distance from ground roll until reaching
a point equidistant to Vlof &V2
above the takeoff surface in case of 😞EF @ V1

Stop way

Beyond the Runway, above its Extended Centerline, Under Airport Authorities,

Must be Rigid surface.
As Wide As Runway,

increasing aircraft's Weight, that it's

Able to Support during an Aborted T/O.

ASDA

Accelerated Stop Distance Available
Runway Length + Stopway

Clearway (CWY)

Area Clear from objects or any terrain.
Beyond the runway, above its Extended Centerline, Under Airport Authorities,

Might Not be a Rigid surface.

Minimum Width of 500 feet,

Upward Slope not exceeding 1.25%
Increasing Weight & Decreasing V1
to enhance Accelerate Stop Distance.

TODA

Takeoff Distance Available
Runway length+ Clear Way

Unbalanced Field Length (mtkawesa)

TODR ≠ ASDR
Clearway or Stopway Used

Balanced Field Length

TODR = ASDR
Clearway or Stopway are 'Not Used'

Balanced Takeoff

TODR = ASDR

Balanced V1

V1 when the TODR = ASDR

Climb Gradient

Percentage (%) of Height achieved to

Ground Distance crossed.

Gross gradient = 2.4% (2 engines, aircraft)
Net Gradient = 1.6% (used daily)

Factors Affecting Net & Gross Gradients (weight)

• Flaps Configuration
• V1
• V2

Notical mile

=6080 feet

TakeOff Path

actual flight path from 35ft to 1,500ft above the takeoff surface
in case of 😞Engine Failure.

Thrust

Pushing force exerted by the engine of an aircraft.
Affected by:
1.Pressure
2.Temperature
3.Humidity
4.Airspeed

1st Sigment

start from 35’ till

Landing Gear Fully Retracted, @ constant V2 speed

using

• T/O Thrust, T/O Slats & Flaps,

• with +ve Minimum Climb Gradient

2nd sigment

From Landing Gear fully Retracted to at least 400’ AGL@ constant V2 speed

using

• T/O Thrust, T/O Slats & Flaps,

• 2.4% Minimum Climb Gradient

3rd sigment

Horizontal Distance to Accelerate to Final Climb Speed, using

• T/O Thrust,

• Retracted Slats & Flaps

4th sigment

Start from End of Third segment
to at least 1500ft @Final Climb Speed with

• Maximum Continuous Thrust (MCT)

• Retracted Slats & Flaps

• 1.2% Minimum Climb Gradient

Take/Off Thrust

Maximum Thrust Engine Can Produce for
5 minutes 'Both Engines operating'
10 minutes in case of EF.

Go/Around Thrust

same as the maximum takeoff thrust,

with the higher speeds during go-around

Maximum Continuous Thrust

Maximum Thrust Engine Can Produce in Case of Engine Failure Continuously.

Maximum Climb Thrust

Lower than Maximum Continuous Thrust
used in reaching Cruise Speed.
En-route climb & Step Cimb

Step Climb

Series of altitude Gains,

Improving Fuel Efficiency

by Moving into Thinner air.

Preformed around Optimum Altitude,
within 1% Loss range.

Optimum Altitude

Altitude at which Best Fuel to Milage occurs.

Wind Altitude Trade (or) Break Even Wind

Wind Required to Maintain Present

Specific Range @New Altitude.

Maximum Cruise Thrust

Maximum thrust usable during the cruise

Improved Climb Performance Technique

Using Excess RW

Accelerating to Higher Speeds,
Achieving higher Climb Gradient,
Resulting in higher Take Off Weights

QRH

stands for Quick Reference Handbook.

• Includes T/O performance tables and charts.

• Accessible anytime by pilots, Usable at any airport or runway Unlike

  RTOW, which is specific to certain airports/runways.

• Does NOT account for obstacles in the takeoff path.

Items Affecting Takeoff Performance

✅ Controllable Factors:

• Aircraft Configuration:

  • Trim devices

  • Flaps, slats

  • Spoilers

  • Landing gear position

• Wheel Brake Configuration:

  • Antiskid system (ON/OFF)

• Engine Thrust Setting

Gross Weight

❌ Uncontrollable Factors:

• Runway Length

  (+ clearway / stopway availability)

• Runway Condition:

  • Wet, dry, snowy

  • Smooth or rough surface

• Runway Environment:

  • Temperature

  • Pressure (altitude)

  • Slope

• Wind Components

Optimum Takeoff Flaps Settings

Compromisation between 2 values
if Runway's the problem,

more flaps are useful.

if Climb Gradient's the problem,

fewer flaps are useful.

Regulated TakeOff Weight (RTOW)

Maximum Takeoff Weight limited by:

1. Climb limit

2. Tire speed limit

3. Runway limit

4. Brake energy limit

5. Obstacles limit

6. Structure limit

Factors Affecting Engine Thrust

Pressure

Temperature

Humidity

AirSpeed

thrust reduction

• Allowed by regulations, but:

  • Must not exceed 25 (Minimum= 75% of full-rated takeoff thrust)

• Two methods

  1. Assumed Temperature Method (ATM)– Boeing

     -Flex Temperature (Flex) – Airbus

  2. De-rate For Boeing

'ATM' Assumed Temprature Method for Boeing
'FLEX' Fexible temperature for Airbus

Easily calculated Dictated Temp.

Limiting Actual T/O Thrust

Reducing Cost by ⬇Stress on Turbine, ⬆Engine Life

& Fuel Effeciency

D-Rate for Boeing

Replacing the full rated engine by another less thrust engine. Through the FMC.
Very important: the de-rated engine is an entirely different engine but when using the ATM or flex: the VMCG is calculated based on the full rated thrust

Flat Rated Power

Maximum Thrust Output based on Ambient (Outside Air) Temperature
Provided by the Engine

EPR

Engine Pressure Ratio: Measuring Thrust

Tref

higest Temperature engine can provide Flat rated power at.

starts to Decrease After, due to Temp. increase

Tmax

Maximum temperature at which the engine Can provide thrust.

Climb

Portion of flight
Starts at the End of Takeoff Segments &
Beginning of En-Route Climb.

Angle Of Climb

Gaining of Altitude per unit of Horizontal Distance

Best Angle Of Climb 'Vx'

Speed @ which Shortest Distance is required for reaching
a Specific Altitude.

Rate Of Climb

Gaining of Altitude per unit of Time.

Best Rate Of Climb "Vy"

Speed @ which Shortest Time is required for reaching
a Specific Altitude.

IN CASES OF EMERGENCY. FROM THE INITIAL CLIMB TO TOP OF CLIMB (TOC)

• 250 KIAS below 10,000ft referred to as constrained speed (KIAS knots of indicated airspeed)
• 300 KIAS/ 0.78 Machmaintaining 300 knots until switch into Mach number usage
• 0.78 Mach / 300 KIASfor descent • 250 KIAS below 10,000f

Cruise

Phase of flight, From Top of Climb to Top of Descent

approximately 90% of flight.
main pilot's task in this phase is

saving fuel as much as possible

Load Factor (or) G Factor

relation between Lift produced to

A/C Gross Weight
Opposing it.

Maneuvering Margin

Ability of Air surrounding the wings to
Support the aircraft's Weight at High Altitudes

Apparent Gross Weight (or) Equivelant Weight

Actual weight of A/C multiplied by the G Factor.
Consisting of:
1.Actual weight
2.Lift & Gravitational forces of Vertical Acceleration & horizontal Stabilizers
4.Centrifugal forces (in TURNS)

Buffet Boundries

low and high speeds for Initial Buffet
at any Given Altitude and Weight

Low Speed Buffet

caused by Air-flow Separation before Stall.

High Speed Buffet

caused by Shockwaves Formation

Speed Margines (Buffet Margine)

Margin between low and high speeds for initial buffet
at any given Altitude and Weight

Coffin Corner (or) Q Corner (or) Aerodynamic Ceilling

Altitude where it's difficult to keep an airplane in Stable flight where there is

No Margin between low & high-speed buffet boundaries,

while Load Factor is 1.0 g.

Endurance ‘How Long You Last?’

Maximum Time Engine can Operate on Given Fuel quantity

Range ‘How Far Can You Go?’

Maximum Distance in (NAM) Engine can Operate on Given Fuel quantity

Specific Range

Rate of Distance Traveled per Unit of Fuel
Number of nautical air miles (NAM) the aircraft can fly per 1,000 kg of fuel can be calculated using the following equation
Specific Range (SR) = TAS/Total Fuel Flow

Maximum Range Cruise (MRC) ‘More Miles, Less Rush’

Speed Where Maximum Range (Distance to Fuel) is Achieved.

Long Range Cruise (LRC)

faster than MRC, saves time with only 1% loss in SR ‘Fuel Efficiency’.

Maximum Speed Cruise

Provide Maximum cruise thrust,
used when Time is more valuable than Fuel