Brunei DCA CPL(A) Performance cheat sheet

Performance requirements for the CPL(A) derive from ICAO Annex 6 and the State operating rules; Brunei DCA adopts these through its civil aviation regulations and associated advisory material.

Take-off distance required (TODR) is the horizontal distance from the start of the take-off roll to the point where the aeroplane reaches 35 ft above the take-off surface, or a screen height specified for the class.

Take-off run required (TORR) is the ground distance from brake release to the point where the aeroplane becomes airborne, normally where it reaches VLOF.

Landing distance required (LDR) is measured from the 50 ft screen point to the full-stop point on the runway, multiplied by the applicable factor.

Accelerate-stop distance available (ASDA) equals TORA plus any stopway; clearway contributes only to TODA, never to ASDA or TORA.

Declared distances: TORA, TODA, ASDA and LDA are published for each runway direction and may differ between directions.

V1 is the decision speed at which, following an engine failure, the take-off can be continued to a 35 ft screen or rejected within the ASDA.

V2 is the take-off safety speed reached by 35 ft; it must be at least 1.13 VS1 or 1.08 VSR in the take-off configuration.

ISA sea-level conditions: temperature 15 C, pressure 1013.25 hPa (29.92 inHg), density 1.225 kg/m3, and an average lapse rate of 1.98 C per 1000 ft up to 36,090 ft.

ISA tropopause is at 36,090 ft (11 km), where temperature is -56.5 C and pressure is 226.32 hPa; above it temperature is constant to 65,617 ft.

Pressure altitude is indicated altitude with the subscale set to 1013.25 hPa; density altitude is the altitude in ISA at which the prevailing density would occur.

Density altitude in feet approximates pressure altitude plus 120 times the ISA temperature deviation in degrees Celsius.

Density rho equals p divided by (R times T), with p in Pa, R = 287.05 J/(kg K) and T in kelvin; density falls about 1 percent per 300 ft near sea level.

Aerodynamic lift and propeller thrust vary with density; engine power output varies with density and, for turbojets, strongly with temperature.

Humidity lowers air density because water vapour is lighter than dry air; the effect is small but always reduces performance.

QNH is the pressure reduced to sea level; QFE is the pressure at the aerodrome reference point; QNE is 1013.25 hPa.

Field-length limit: TODR must not exceed TODA, TORR must not exceed TORA, and the accelerate-stop distance must not exceed ASDA.

Balanced field length is the runway length at which the accelerate-stop distance equals the all-engines-operating take-off distance; V1 is the corresponding speed.

Obstacle clearance requires the net take-off flight path to clear all obstacles by 35 ft vertically, or a specified lateral separation if the obstacle is not on the extended centreline.

Net take-off path is the gross gradient reduced by 0.8 percent for two-engine aeroplanes, 0.9 percent for three, and 1.0 percent for four.

Minimum second-segment climb gradient is 2.4 percent for two engines, 2.7 percent for three, and 3.0 percent for four, with gear up, one engine inoperative and V2.

First-segment climb (gear down, V2, one engine inoperative) requires a positive gradient of at least 0.5 percent for two-engine aeroplanes.

Take-off flap settings trade field length against climb gradient: more flap shortens the ground roll but reduces the obstacle-clearance gradient.

A clearway permits a reduction in the required TODR but never reduces TORA, ASDA or the accelerate-stop distance.

The landing distance available (LDA) must be at least the landing distance required, which is the demonstrated distance from 50 ft to a full stop multiplied by the required factor.

For turbojet aeroplanes the required factor is 1.67; for propeller aeroplanes it is 1.43; a dry-runway factor of 1.92 may apply to turbojets when the runway is wet or contaminated.

Wet-runway landing distances are typically increased by 15 percent on top of the dry factor unless the AFM provides specific wet data.

Landing distance increases with weight, temperature, pressure altitude, tailwind and downslope; each knot of tailwind adds roughly 2 percent to the ground roll.

Approach speed for landing is 1.3 VSO in the landing configuration, or VREF, and excess approach speed increases the landing distance by about 5 percent per 5 knots.

A 50 ft screen height is the standard reference; a low approach or a glide path below 3 degrees increases the effective landing distance.

Reverse thrust and wheel brakes are not assumed in the certified landing distance unless the AFM states otherwise.

Runway slope affects landing distance approximately by the percentage gradient; a 1 percent downslope adds about 10 percent to the ground roll.

Maximum rate of climb occurs at the speed for maximum excess power; maximum angle of climb occurs at the speed for maximum excess thrust.

Best glide speed is the speed for minimum drag, approximately 1.3 times the speed for minimum power, and gives the maximum range in a power-off glide.

Specific range in cruise is maximised near the speed where (L/D) divided by specific fuel consumption is highest; a headwind shifts the optimum speed higher.

Cruise altitude is limited by the drift-down requirement: the aeroplane must be able to descend at a specified rate to an altitude where it can maintain level flight on remaining engines.

Service ceiling is the altitude at which the maximum rate of climb falls to 100 ft/min; absolute ceiling is where the rate of climb is zero.

Descent gradient in a glide is the ratio of height lost to horizontal distance, and is independent of weight at a given speed and configuration.

Endurance is maximised at the speed for minimum power required, which is lower than the speed for maximum range.

En-route fuel planning accounts for climb, cruise, descent, contingency, alternate and final reserve; the final reserve for turbine aeroplanes is typically 30 minutes at holding speed.

Centre of gravity forward of the limit increases the pitch-down moment, raises stall speed and increases take-off and landing distances.

Centre of gravity aft of the limit reduces longitudinal stability and may make the aeroplane unrecoverable from a stall or spin.

Take-off and landing distances increase with weight; the effect is non-linear because the square of the stall speed and the acceleration both change.

Maximum take-off mass, maximum landing mass and maximum zero-fuel mass are separate limits, and the lowest applicable one governs the flight.

Moment equals weight times arm; the centre of gravity is the total moment divided by the total weight, expressed as a percentage of mean aerodynamic chord.

Zero-fuel mass is the mass of the aeroplane and its contents excluding usable fuel; it must not exceed MZFM.

Load sheet computations use index units or moment arms; a forward CG reduces the elevator authority available for rotation.

Operating empty mass includes crew and unusable fuel but excludes payload and usable fuel; it is the basis for all loading calculations.

A headwind component reduces ground roll in proportion to the square of the ground speed; a 10 percent headwind reduces the ground roll by roughly 19 percent.

A tailwind increases take-off and landing distance; the increase is about 20 percent for a 10 percent tailwind component, and tailwind take-offs may be prohibited.

Runway slope: an upslope increases the take-off ground roll and decreases the landing roll; a 1 percent upslope adds about 10 percent to the take-off distance.

Wet runways reduce braking friction; standing water, slush, snow and ice further reduce it and can cause aquaplaning or loss of directional control.

Contaminated runway data in the AFM is specific to the contaminant type and depth; the take-off distance may increase by 100 percent or more on slush or snow.

Grass, gravel or soft surfaces increase rolling resistance and reduce acceleration; the AFM provides separate factors for each surface type.

Crosswind component equals wind speed times the sine of the angle between wind and runway; the crosswind limit is a demonstrated value in the AFM.

Runway surface condition reports use terms such as dry, damp, wet, standing water, slush, snow and ice; the reported braking action affects the usable landing distance.

The AFM is the approved document for the aeroplane type; performance data in it is certified and must be used in preference to any other source.

Charts are entered with pressure altitude, temperature, weight, wind and runway slope; intermediate values are obtained by interpolation between the plotted lines.

Read each chart at the correct reference conditions and apply the corrections in the order stated in the notes, typically wind, slope, surface and contamination.

Do not extrapolate beyond the limits of a chart; data outside the plotted range is not certified and must not be used.

Distances on AFM charts are normally given for ISA, zero wind, level dry runway and a specified flap setting; any deviation requires a correction.

The first-segment, second-segment and final take-off climb gradients are plotted separately; the limiting gradient determines the maximum weight.

Landing charts assume a 50 ft screen and full braking; reverse thrust and other non-certified aids are not included unless stated.

Performance data is valid only for the configuration and procedures specified; deviations such as unapproved flap settings invalidate the figures.

High elevation, high temperature and high humidity all reduce air density and therefore reduce lift, thrust and propeller efficiency.

Density altitude increases by about 120 ft for each degree Celsius above ISA at a given pressure altitude.

True airspeed for a given indicated airspeed increases with density altitude; the ground speed and take-off run increase accordingly.

High density altitude raises the true stalling speed and the true take-off speed, lengthening the ground roll and reducing the climb gradient.

Turbojet and turboprop engines lose thrust with increasing temperature; the effect is most severe above the flat-rated temperature.

Humidity has a small effect on density but a larger effect on engine performance in some installations; it is never beneficial.

Mountain airports combine high elevation with high temperature; the resulting density altitude may exceed the aerodrome elevation by several thousand feet.

Landing distance also increases with density altitude because the true approach speed and the true touchdown speed are higher.