032 Flight Performance
Definitions
Aerodrome Any area of land or water designed, equipped, set apart or commonly used for affording facilities
for the landing and departure of aircraft, but shall not include any area the use of which for
affording facilities for the landing and departure has been abandoned and has not been resumed.
Elevation: The elevation of the highest point of the landing area.
Reference Point: geographical location and the centre of where an ATZ is established.
Aircraft A machine that can derive support in the atmosphere from the reactions of the air other than the
reactions of the air against the earth’s surface.
Turbojet: the energy of the jet operates a turbine that in turn operates the air compressor.
Turboprop: the energy of the jet operates a turbine that drives the propeller.
Aeroplane A power-driven heavier-than-air aircraft, deriving its lift in flight chiefly from aerodynamic
reactions on surfaces which remain fixed under given conditions of flight.
Large Aeroplane: more than 5700 kg maximum certificated take-off weight.
Aircraft Value to show aeroplane load force. The aircraft classification number must be compared to the
Classification pavement classification number (PCN) of an aerodrome, may exceed the PCN by as much as 50%
Number (ACN) but only if the manoeuvring of the aeroplane is very carefully monitored.
Airframe The fuselage, booms, nacelles, cowlings, fairings, aerofoil surfaces (including rotors but excluding
propellers and rotating aerofoils of engines), and landing gear of an aircraft and their accessories
and controls.
Alternate Airport An airport at which an aircraft may land if a landing at the intended airport becomes inadvisable.
Altitude Density Altitude: The altitude in ISA, where the prevailing measured density occurs.
“A high Density Altitude is one that represents a higher altitude in the International Standard
Atmosphere”.
Elevation: The vertical distance of an object above mean sea level.
Pressure Altitude: The altitude of an aircraft above the pressure level of 1013.25 hPa.
Flight Level: A surface of constant atmospheric pressure that is related to 1013.25 hPa.
Height: The vertical distance between the lowest part of the aeroplane and the relevant datum.
Angle of Attack Angle between the chord line of the wing of an aircraft and the relative airflow.
Apron Defined area on a land aerodrome provided for the stationing of aircraft for the embarkation and
disembarkation of passengers, the loading and unloading of cargo, and for parking.
Auxiliary power Any gas turbine-powered unit delivering rotating shaft power, compressor air, or both which is
Unit not intended for direct propulsion of an aircraft.
Baulked Landing A landing manoeuvre that is unexpectedly discontinued.
Brake Horsepower The power delivered at the main output shaft of an aircraft engine
Buffet Speed The speed at which the airflow over the wing separates creating turbulent airflow aft of the
separation point which buffets the aeroplane.
Ceiling Absolute Ceiling: The altitude at which the theoretical rate of climb, with all engines operating at
maximum continuous power, is reduced to 0 ft/min.
Service Ceiling: The pressure altitude at which the rate of climb is reduced to a specified
minimum value (approximately 300 ft/min).
Cloud Ceiling: The vertical distance from the elevation of the aerodrome to the lowest part of any
cloud visible from the aerodrome which is sufficient to obscure more than one half of the sky.
,Continuous One Power Rating: The minimum test bed acceptance power, as stated in the engine type certificate
Engine Inoperative data sheet, when running at the specified conditions and within the appropriate acceptance
limitations.
Thrust Rating: The minimum test bed acceptance thrust, as stated in the engine type certificate
data sheet, when running at the specified conditions and within the appropriate acceptance
limitations.
Power: The power identified in the performance data for use after take-off when a power unit has
failed or been shut down, during periods of unrestricted duration.
Thrust: The thrust identified in the performance data for use after take-off when a power unit has
failed or been shut down, during periods of unrestricted duration.
Critical Engine The engine whose failure would most adversely affect the performance or handling qualities of
an aircraft.
Declared The distances declared by the aerodrome authority for the purpose of application of the
Distances requirement of the Air Navigation Order.
Exhaust Gas The average temperature of the exhaust gas stream.
Temperature
Forces Drag: That force on an aeroplane which directly opposes thrust.
Lift: That force acting on an aerofoil which is at right angles to the direction of the airflow.
Thrust: That force acting on an aeroplane produced by the engine(s) in a forward direction.
Weight: m*g
Frangibility The ability of an object to retain its structural integrity and stiffness up to a specified maximum
load but when subject to a load greater than specified or struck by an aircraft will break, as to
present minimum hazard to an aircraft.
Go-around A procedure involving a decision to abort the landing and climb straight ahead to rejoin the
circuit. Such a decision might be taken at any time during the final approach,
ICAO Standard Atmosphere defined in ICAO Document 7488/2:
Atmosphere • The air is a perfect dry gas
• The temperature at sea level is 15°C
• The pressure at sea level is 1013.2 hPa (29.92 in Hg)
• The temperature gradient from sea level to the altitude at which the temperature
becomes –56.5°C is 0.65°C/100 m (1.98°C/1000 ft)
• The density at sea level under the above conditions is 1.2250 kg/m^3
IFR conditions Weather conditions below the minimum for flight under visual flight rules.
Instrument A device using an internal mechanism to show visually or aurally the attitude, altitude, or
operation of an aircraft or aircraft part. It includes electronic devices for automatically controlling
an aircraft in flight.
Load Factor The ratio of a specified load to the total weight of the aircraft.
The specified load is expressed in terms of any of the following: aerodynamic forces, inertia
forces, or ground or water reactions.
Maximum Power: power identified in the performance data for use during periods of unrestricted duration.
Continuous Thrust: thrust identified in the performance data for use during periods of unrestricted duration.
Missed Approach When an aircraft is caused to abort a landing after it has already started its landing approach.
Outside Air The free air static (ambient) temperature.
Temperature
Pitch Setting The propeller blade setting determined by the blade angle
Pitot Tube A small tube whose open end collects Total Pressure.
Propeller Fixed Pitch: A propeller, the pitch of which cannot be changed.
, Variable Pitch: A propeller, the pitch of which changes or can be changed, when the propeller is
rotating or stationary.
Rejected Take-off A situation or event in which it is decided, for safety reasons, to abandon the take-off of an
(RTO) aircraft.
Roll Motion of the aeroplane about its longitudinal axis.
Runway Strip: An area of specified dimensions enclosing a runway intended to reduce the risk of damage
to an aircraft running off the runway and to protect aircraft flying over it.
Threshold: The beginning of that portion of the runway usable for landing.
Take-off Mass
Power
Thrust
Taxiway A defined path on a land aerodrome established for the taxiing of aircraft and intended to provide
a link between one part of the aerodrome and another.
Windshear Localized CHANGE IN WIND SPEED AND/OR DIRECTION over a short distance, resulting in a
tearing or shearing effect that can cause a sudden change of airspeed.
Yaw Motion of an aeroplane about its normal axis.
, EU-OPS Performance Classification
Class A (CS-25) Multi-engine aeroplanes powered by turbo-propeller engines with a maximum approved passenger
seating configuration of more than 9 Seats or a maximum take-off mass exceeding 5700 kg,
All multi-engine turbojet powered aeroplanes.
Class A aeroplanes must abide by the Certification Specifications laid out in the EASA CS-25.
Class B (CS-23) Propeller driven aeroplanes with a maximum approved passenger seating configuration of 9 or less
seats, and a maximum take-off mass of 5700 kg or less.
Class B aeroplanes must abide by the Certification Specifications laid out in the EASA CS-25.
Class C Aeroplanes powered by reciprocating engines with a maximum approved passenger seating
configuration of more than 9 seats or a maximum take-off mass exceeding 5700 kg.
Unclassified This class is given to those aeroplanes whose performance characteristic is unique and special
performance consideration is required.
For example, the Unclassified class includes supersonic aeroplanes and sea planes.
Performance Expression
To achieve the required safety standard, the aviation authorities have added a safety margin into the aeroplane
performance data. The application of these safety margins changes the expression of the performance data.
Measured performance Achieved by the manufacturer under test conditions for certification.
It utilizes new aeroplanes and test pilots and is therefore unrepresentative of the
performance that will be achieved by an average fleet of aeroplanes.
Gross Performance Gross performance is the average performance that a fleet of aeroplanes should achieve if
satisfactorily maintained and flown in accordance with the techniques described in the
manual.
Gross performance is measured performance reduced by a set margin to reflect average
operating performance.
Gross Height The true height attained at any point in the take-off flight path using gross climb
performance.
Gross height is used for calculating pressure altitudes for purposes of obstacle clearance
and the height at which wing flap retraction is initiated.
Net Performance Net performance is the gross performance diminished to allow for various contingencies
that cannot be accounted for operationally e.g. variations in piloting technique, temporary
below average performance, etc.
It is improbable that the net performance will not be achieved in operation, provided the
aeroplane is flown in accordance with the recommended techniques. This level of
performance is approximately 5 standard deviations from the average performance or
gross performance.
Therefore, 99.99994% of the time, the aeroplane will achieve net performance or better.
However, there is less than one chance in a million that the aeroplane will not achieve the
net performance.
This is the safety standard which the aviation authorities aim to achieve.
Net Height The true height attained at any point in the take-off flight path using net climb
performance.
Net height is used to determine the net flight path that must clear all obstacles by the
statutory minimum to comply with the Operating Regulations.
