CPL Helicopter flashcards

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

Right-of-way in converging flight

When two aircraft converge at the same level, the one with the other on its right gives way. Helicopters also give way to aeroplanes, gliders and balloons, and every aircraft gives way to balloons.

VFR fuel reserve

Planned fuel must include trip fuel plus a reserve allowing at least 30 minutes of flight by day at cruising level, commonly increased to 45 minutes by night or in instrument conditions.

Certificate of airworthiness

Document confirming the helicopter conforms to its approved type design and is maintained per the approved programme; operating without a valid certificate is unlawful.

Semi-rigid rotor head

Two-blade design using an underslung flapping hinge that allows the disc to teeter as a unit, with no individual lead-lag hinges; found on many light piston helicopters.

Freewheel unit

One-way clutch between engine and rotor that transmits power to the rotor but allows the rotor to overrun the engine during autorotation or engine failure.

Hover in ground effect

Hover at a height up to about one rotor diameter, where reduced induced velocity near the surface lowers the power required compared with out-of-ground-effect hover.

Density altitude formula

Pressure altitude plus roughly 120 feet for each degree Celsius the temperature is above the standard atmosphere value at that level; used to correct performance charts.

Hover out of ground effect ceiling

The maximum density altitude at which the helicopter can hover clear of ground effect at a given weight; above it, a descent or loss of control occurs.

Centre of gravity limits

Certified fore and aft and lateral boundaries within which the loaded helicopter must remain for all fuel states; exceeding them degrades control and may be unsafe.

Time of useful consciousness

The interval after loss of oxygen during which a pilot can still act effectively; at 25 000 feet it is only about three to five minutes.

Somatogravic illusion

A false sensation of climbing during acceleration or descending during deceleration, caused by otolith stimulation; the pilot must rely on instruments.

Carbon monoxide hazard

Odourless exhaust gas that causes headache, confusion and loss of consciousness; suspect it if cabin heat is on and symptoms appear, then shut heat and ventilate.

QNH versus QFE

QNH set on the altimeter subscale shows altitude above mean sea level; QFE shows height above a specified reference point such as the aerodrome.

Mountain wave signs

Strong winds across a ridge with lenticular cloud, rotor cloud and severe turbulence on the lee side; downdrafts may exceed the helicopter's climb capability.

Carburettor icing range

Icing may form with outside temperatures between about minus seven and plus twenty-one degrees Celsius, especially at high humidity; carburettor heat is the remedy.

One-in-sixty rule

A track error of one nautical mile after sixty nautical miles flown equals one degree; the same ratio converts off-track distance into a heading correction.

Magnetic variation and deviation

Variation is the angle between true and magnetic north at a location; deviation is the compass error on a given heading, read from the correction card.

RAIM prediction

Receiver autonomous integrity monitoring checks whether enough satellites are available to guarantee position accuracy; required before conducting GNSS approaches.

Stabilised approach gate

A defined height and speed by which the approach must be stabilised; if not, a go-around is flown rather than continuing to land.

Passenger safety briefing

Short briefing covering seat belts, doors, rotor hazard, no smoking, evacuation and the location of emergency equipment; required before every flight carrying passengers.

Read-back requirement

Clearances, hold-short instructions, runway-in-use, altimeter settings and frequencies must be repeated back to the controller to confirm correct reception.

Translational lift

Above roughly fifteen to twenty knots, the rotor leaves its own downwash, reducing induced power and improving efficiency; hover power drops noticeably.

Dissymmetry of lift

In forward flight the advancing blade meets higher relative airflow than the retreating blade; flapping and cyclic feathering equalise lift across the disc.

Settling with power

Vortex ring state from high power, low airspeed and descent above about 300 feet per minute; recovery is by increasing speed or reducing collective.

Blade coning

Upward bending of blades under lift, increasing with weight and collective; excessive coning reduces disc area and raises bending loads on the blade roots.

MAYDAY call

Distress signal spoken three times, followed by station addressed, callsign, nature of distress, position, altitude and intentions; it has absolute priority.

PAN PAN call

Urgency signal spoken three times, used when safety is not immediately threatened but assistance may be needed; it ranks below distress traffic.

Transponder emergency codes

Squawk 7500 for unlawful interference, 7600 for radio failure and 7700 for general emergency; Mode C additionally reports pressure altitude.

Autorotation landing flare

At about fifty to seventy-five feet, flare to reduce rate of descent, level the helicopter, then apply collective to cushion touchdown while rotor RPM remains available.

Dynamic rollover prevention

Avoid any pivot about a caught skid or wheel by applying smooth collective, keeping the disc level and correcting roll immediately with cyclic input.

Ground resonance

Destructive oscillation between rotor imbalance and landing gear; if it starts on the ground, lift off immediately to remove the ground contact.

Tail rotor failure response

Reduce collective, maintain forward speed above translational lift and fly a running landing; in hover, land immediately with minimal collective change.