CPL Flight Performance and Planning flashcards

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

Induced drag

Drag caused by lift, proportional to the square of the lift coefficient and inversely proportional to the square of speed. It dominates at low speed and high angle of attack.

L/D maximum

The lift-to-drag ratio peaks at the speed where parasite and induced drag are equal. This speed gives best glide range and best specific range in still air.

Load factor in a turn

In a level turn, load factor equals one divided by the cosine of the bank angle. At 60 degrees bank the load factor is two, so stall speed rises by about 41 percent.

Density altitude

Pressure altitude corrected for temperature deviation from ISA. It is the entry value for takeoff, climb, and landing performance charts because it reflects air density.

Excess power

The difference between power available and power required. Divided by weight, it gives the rate of climb; it is greatest at the altitude where the two curves are furthest apart.

Centre of gravity formula

Total moment divided by total mass, where each moment is the item mass multiplied by its arm from the datum. The result must lie within the certified forward and aft limits.

Zero fuel mass

The mass of the aircraft plus payload but without usable fuel. It has its own structural limit and is used to check that the wing bending loads remain within certification.

CG shift from moving load

Moving a mass by a distance shifts the centre of gravity by the mass times the distance divided by the total mass. The shift is in the direction of the movement.

Forward CG effects

A forward centre of gravity increases stall speed, lengthens the takeoff run, increases elevator forces for rotation, and reduces cruise range, but improves longitudinal stability.

Balanced field length

The runway length at which the accelerate-stop distance equals the accelerate-go distance, defining the critical V1. Increasing mass or reducing thrust lengthens it.

V1 decision speed

The speed at which a failure is recognised and the takeoff can still be continued or stopped within the runway. It must not be less than minimum control speed on the ground.

Takeoff distance required

Ground roll plus the airborne segment to the screen height, normally 35 feet. It must not exceed the takeoff distance available after wind, slope, and contamination corrections.

Hydroplaning speed

The speed above which tyres lose contact with a wet runway, roughly nine times the square root of tyre pressure in psi. It degrades braking and directional control.

Landing distance required

The distance from the 50-foot screen height to a full stop with full braking. Wet or contaminated runways apply a factor and reduce the braking coefficient.

Climb gradient formula

One hundred times the rate of climb in feet per minute divided by groundspeed in knots times 101.3. A headwind steepens the gradient for a fixed rate of climb.

Net takeoff flight path

The gross flight path reduced by a gradient decrement of 0.8 to 1.0 percent depending on engine count. It must clear all obstacles by 35 feet vertically.

Specific range

Distance flown per unit of fuel, usually nautical miles per kilogram. It peaks near the speed for maximum lift-to-drag ratio and decreases with headwind.

Top of descent

The point where descent begins, computed as altitude to lose divided by the planned descent gradient in feet per nautical mile. A three-degree path loses about 318 feet per nautical mile.

Final reserve fuel

A fixed regulatory quantity, typically 30 minutes holding at 1500 feet for commercial aeroplanes. It must remain on board at landing and is not usable for planning.

Contingency fuel

Fuel added to the trip fuel, commonly five percent, to cover unforeseen deviations. It may be reduced under approved statistical or decision-point methods when an en-route alternate exists.

Alternate fuel

Fuel to fly from the destination to the chosen alternate via the planned route, including approach and landing. It is computed at the planned landing mass and altitude.

Equal time point

The point where time to the diversion aerodrome equals time back to the departure aerodrome. Distance to it equals total distance times outbound groundspeed divided by the sum of groundspeeds.

Density altitude entry

Pressure altitude plus 120 times the difference between actual temperature and ISA temperature at that altitude. It is used as the entry for takeoff and climb charts.

Wind component resolution

Headwind equals wind speed times the cosine of the angle off the runway; crosswind equals wind speed times the sine of that angle. Use the components, not the reported wind.

Chart interpolation

Read the entry axes, locate the value between grid lines, and interpolate linearly only in the variable shown. Never extrapolate beyond the chart boundary.

Chart configuration assumptions

Performance charts assume a specific flap setting, bleed configuration, and anti-ice state. Correct the result when the actual configuration differs from the chart assumption.

Takeoff alternate

An aerodrome to which an aircraft can proceed if the departure aerodrome cannot be used after takeoff. It is required when return to the departure point is not possible.

Destination alternate

An aerodrome to which an aircraft can proceed if approach and landing at the destination are not possible. It is normally required unless visual approach conditions are assured.

ETOPS diversion time

The approved maximum time for a twin-engine aircraft to reach an adequate aerodrome after an engine failure. It limits the route and depends on aircraft performance and systems.

Performance-limited mass

The lowest mass permitted by field length, climb gradient, obstacle clearance, tyre speed, or brake energy at the critical segment. It may be below the structural maximum takeoff mass.

Minimum fuel declaration

A statement to air traffic control that fuel is such that landing at the destination below final reserve is possible. It requires priority handling but is not an emergency.

In-flight reclearance

An amended clearance issued en route that changes the destination and fuel plan using updated weather and performance data. It allows the crew to replan fuel before arrival.