NCAA CPL Flight Performance & Planning flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

Centre of gravity formula

CG position equals total moment divided by total mass, where each item's moment is its mass multiplied by its arm from the datum. Arms forward of the datum are negative, so signs must be applied consistently.

Zero-fuel mass

Take-off mass minus usable fuel. It must not exceed maximum zero-fuel mass, which is usually the structural limit on payload; exceeding it requires reducing payload or fuel before departure.

Dry operating mass

Empty mass plus crew, crew baggage, catering and potable water. It excludes traffic load and usable fuel, and its associated index is the dry operating index used on the load sheet.

CG shift for moved mass

When a mass is moved within the aircraft, the CG moves by (mass moved x distance moved) divided by total mass, in the direction of the move. Fuel transfer between tanks is a common application.

Aft CG limit reason

The aft limit is set by longitudinal static and dynamic stability requirements. An excessively aft CG reduces stick-fixed stability and can make stall and spin recovery difficult or impossible.

Floor loading limit

A structural limit expressed as mass per unit area, or running load per metre of fuselage. A load within maximum take-off mass can still exceed it, so it is checked separately.

Index formula

Index equals moment divided by a constant, plus a reference constant K. The load sheet converts total index back to CG position using the aircraft's index-to-CG table.

Density altitude formula

Density altitude equals pressure altitude plus 120 times the difference between outside air temperature and ISA temperature at that level. It governs take-off distance and climb performance.

Balanced field length

The runway length at which the accelerate-stop distance equals the accelerate-go distance to 35 ft. V1 is chosen so that the field length required is minimised for the given mass.

V1 decision speed

The speed at which an engine failure is recognised and the decision to stop or continue is made. It must not be less than VMCG and must allow the aircraft to stop within the runway.

V2 take-off safety speed

The minimum speed to be attained by 35 ft above the take-off surface with one engine inoperative. It must not be less than 1.13 VS1 or VMC, whichever is higher.

Second-segment climb gradient

With gear up, one engine inoperative, take-off flaps and V2, the gross gradient must be at least 2.4% for twins, 2.7% for three engines and 3.0% for four engines.

Net take-off flight path

The gross flight path reduced by 0.8% for twins and 0.9% for three engines. The net path must clear all obstacles by at least 35 ft vertically.

Wind correction rule

Apply only 50% of a reported headwind and 150% of a reported tailwind to take-off and landing distance calculations, unless the operator's approved procedure specifies a different conservative rule.

Landing distance required

The distance from 50 ft above the threshold to a full stop, corrected for wind, slope and surface. It must not exceed landing distance available, and contaminated runways require additional factors.

VREF landing reference speed

The target speed at the 50 ft point in the landing configuration, normally 1.3 times the stall speed in the landing configuration. It is used for landing distance and approach planning.

TODA and TORA

Take-off distance available includes the clearway; take-off run available is the physical runway length. The take-off run required must not exceed TORA, and the distance required must not exceed TODA.

Operational flight plan

The pilot's document recording route, levels, masses, fuel and performance for the flight. It is distinct from the ATS flight plan filed with air traffic services.

Wind triangle equation

The wind correction angle satisfies sine of the angle equals wind speed times sine of the wind angle minus track, divided by TAS. Groundspeed follows from TAS and the wind component along track.

Point of no return

The point from which the fuel to return to base equals the fuel to continue. It is computed from fuel available, groundspeeds out and back, and fuel consumption per hour.

Critical point

The point from which the fuel required to reach the destination equals the fuel required to return to base. It is computed like the point of no return but with the destination as the alternate.

Mach number relation

Mach number equals true airspeed divided by the local speed of sound. The speed of sound falls with temperature, so a given Mach number corresponds to a lower TAS in cold air.

Great-circle distance

Sixty nautical miles per degree of angular distance along the great circle. The rhumb line is a constant-track line that is longer than the great circle except on the equator or a meridian.

Navigation log purpose

It records waypoint, track, TAS, wind, heading, groundspeed, distance, ETA, fuel flow and fuel remaining for each leg, allowing in-flight comparison with the plan and timely re-planning.

Contingency fuel

Normally 5% of trip fuel, or 3% under an approved scheme with a suitable en-route alternate. It covers unforeseen deviations from the planned route and is not intended for holding.

Final reserve fuel

Fuel to hold for 30 minutes at 1500 ft above the aerodrome in ISA conditions, for turbine aeroplanes. It must remain on landing and must not be planned for use.

Alternate fuel

Fuel from the destination to the alternate, including a missed approach, climb and descent. If two alternates are required, the fuel for the more distant one is used.

Taxi fuel

Fuel consumed before take-off, including engine start and APU use. It is added to trip, contingency, alternate and final reserve fuel to give the minimum block fuel.

Minimum fuel declaration

Declared when the aircraft can only land with the final reserve intact. It is an advisory to ATC, not an emergency, but any further delay may lead to a mayday fuel situation.

Mayday fuel

Declared when the fuel remaining is below the final reserve and the aircraft is committed to landing at the nearest suitable aerodrome. The crew must declare an emergency to ATC.

Fuel density effect

Jet fuel density varies with temperature, so mass must be derived from volume and density. A 1 C change alters Jet A-1 density by about 0.0008 kg per litre, affecting mass and balance.

Fuel tankering

Carrying extra fuel because it is cheaper at the departure aerodrome. The extra mass increases take-off and landing masses, so the cost saving must be weighed against the performance penalty.

Commander fuel authority

The commander has final authority over fuel and may add extra fuel. The operator must provide a fuel policy meeting the regulations, and the commander may deviate only in the interest of safety.