BDCA PPL Knowledge Exam flashcards

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

Quadrantal rule

IFR cruising levels above 3000 ft AGL: magnetic tracks 000 to 179 use even flight levels, tracks 180 to 359 use odd flight levels, ensuring opposite-direction traffic is separated by 1000 ft.

Transition altitude

The altitude at or below which vertical position is expressed as altitude on the QNH; above it, flight levels on standard pressure 1013.2 hPa are used.

Right of way

Converging aircraft of the same category: the one on the right has right of way. Head-on: both turn right. Overtaking: the overtaken aircraft has priority. Landing aircraft have priority over ground traffic.

VFR cloud separation

Below 10 000 ft AMSL in controlled airspace: 5 km flight visibility, 1500 m horizontally and 300 m vertically from cloud. At or above 10 000 ft: 8 km and 1500 m/600 m.

Four-stroke cycle

Induction, compression, power and exhaust strokes; the crankshaft turns 720 degrees per complete cycle, so each cylinder produces one power stroke every two revolutions.

Detonation

Explosive uncontrolled combustion causing high peak pressures and temperatures with audible knocking; caused by low octane fuel, lean mixture, high manifold pressure at low RPM or high inlet temperature.

Magneto check

During the run-up each magneto is selected in turn; maximum drop is about 175 RPM and maximum difference between magnetos about 50 RPM, proving both ignition circuits operate.

Blocked static port

With the static source blocked, the airspeed indicator over-reads in a climb and under-reads in a descent, the altimeter freezes and the vertical speed indicator stops responding.

Centre of gravity formula

Total moment divided by total mass gives the CG position; each item's moment is its mass multiplied by its arm from the reference datum, and the result must lie within the certified limits.

Density altitude

Pressure altitude corrected for temperature: add 120 ft for each degree Celsius the outside air temperature exceeds ISA. High density altitude reduces power, thrust and lift and lengthens take-off.

Best angle of climb

Vx gives the greatest height gain per unit horizontal distance and is used to clear obstacles; Vy gives the greatest height gain per unit time and is used for normal climb.

Final reserve fuel

Fuel required to hold for 30 minutes at 1500 ft above the aerodrome for VFR flight, added to trip, contingency, alternate and taxi fuel in the flight plan.

Hypoxia signs

Euphoria, impaired judgement, cyanosis, headache and breathlessness; time of useful consciousness falls from about 3 to 5 minutes at 25 000 ft to 30 to 60 seconds at 35 000 ft.

Hyperventilation

Excessive breathing rate lowers carbon dioxide, causing dizziness, tingling and cramps; treatment is to slow the breathing rate, and if hypoxia is possible, use 100 percent oxygen.

Somatogravic illusion

A sudden acceleration is misinterpreted by the vestibular system as a climb, and a deceleration as a descent; the pilot must rely on instruments, especially in low visibility.

Dark adaptation

The eyes need about 30 minutes to adapt to darkness; rod vision is used and is degraded by smoking, high altitude and bright light, so avoid white light before night flight.

ISA conditions

Sea level temperature 15 degrees Celsius, pressure 1013.25 hPa, temperature lapse rate 1.98 degrees Celsius per 1000 ft up to the tropopause at about 36 090 ft and -56.5 degrees Celsius.

Cloud base estimate

Cloud base in feet is approximately the temperature-dewpoint spread in degrees Celsius multiplied by 400; a small spread indicates a low cloud base and high humidity.

Carburettor icing

Can occur at outside air temperatures between about -7 and +21 degrees Celsius, especially with high humidity; it reduces power and is indicated by a drop in RPM, treated with carburettor heat.

Cold front passage

A cold front has a steep slope, a narrow band of heavy showers, a rapid wind veer and a temperature drop, with good visibility behind the front and a risk of thunderstorms.

QNH and QFE

QNH set on the altimeter gives elevation above mean sea level; QFE gives height above the aerodrome reference point. QNE is standard pressure 1013.2 hPa giving flight levels.

Great circle

The shortest path between two points on the Earth's surface; on a Mercator chart it appears as a curved line, while the rhumb line is a straight constant-track line.

Triangle of velocities

True heading and true airspeed combined with the wind vector give track and groundspeed; drift is the angle between heading and track and the wind correction is applied into the wind.

VOR radial

The VOR receiver displays the magnetic bearing from the station; with the CDI centred and a FROM indication the aircraft is on the selected radial, and the TO/FROM flag shows the sense.

ADF relative bearing

The angle measured clockwise from the aircraft heading to the direction of the station; magnetic bearing to the station equals heading plus relative bearing, and the needle points to the station.

ILS glidepath

The glidepath provides vertical guidance, normally at 3 degrees, giving about 300 ft of height per nautical mile; decision height is referenced to the radio altimeter.

Engine failure after take-off

Lower the nose to maintain flying speed, select a landing area ahead, do not turn back below 500 ft, complete restart checks, transmit MAYDAY and brief passengers.

Wake turbulence

Wingtip vortices are strongest when the generating aircraft is heavy, clean and slow; take off before and land after a heavy aircraft and stay above its flight path.

Radio failure squawk

Squawk 7600 for radio failure, 7700 for emergency and 7500 for unlawful interference; in VMC continue and land at the nearest suitable aerodrome and report.

Load factor in turn

In a level turn the load factor equals 1 divided by the cosine of the bank angle; at 60 degrees it is 2, and stall speed rises by the square root of the load factor.

Induced drag

Drag caused by the generation of lift; it increases with the square of the lift coefficient and decreases as speed squared increases, so total drag is minimum where induced equals parasite drag.

Stall recovery

Reduce the angle of attack by moving the control column forward, keep the wings level with rudder, and add power as height is regained; counter a wing drop with rudder, not aileron.