Oman CAA PPL Theory Exam key terms

The minimum flight visibility and distance from cloud that a pilot flying under visual flight rules must maintain, varying with airspace class and altitude.

Uncontrolled airspace in which IFR and VFR traffic are not separated by ATC; VFR pilots remain responsible for their own separation and must meet the applicable VFR minima.

A clearance allowing a VFR flight to operate inside a control zone when weather is below normal VFR minima, subject to ATC approval and specified visibility and cloud clearance conditions.

Controlled airspace extending upwards from the surface around an aerodrome, within which ATC clearance is required and special VFR may be authorised in poor weather.

The rule requiring IFR flights above a specified altitude to choose flight levels according to magnetic track, so that opposing traffic is separated by at least 1000 feet.

A track-based cruising level rule historically used for IFR flights below the transition altitude, assigning levels by magnetic track quadrant to keep opposing traffic vertically separated.

The altitude at or below which aircraft set altimeters to local QNH and above which they set standard pressure 1013.2 hPa, as published for each aerodrome or area.

The lowest flight level available for use above the transition altitude, ensuring at least 1000 feet of vertical separation between aircraft using QNH and those using standard pressure.

A surface of constant atmospheric pressure referenced to 1013.2 hPa, expressed in hundreds of feet, used above the transition altitude to give all aircraft a common pressure reference.

A service provided by ATC using radar, ADS-B or multilateration to identify aircraft and provide position information, traffic information and, where approved, separation.

A four-digit octal code entered in the aircraft transponder so that ATC surveillance systems can identify the flight on their displays.

The transponder reply that transmits pressure altitude, allowing ATC to display and monitor the aircraft's altitude alongside its position.

The pressure value (QNH, QFE or standard 1013.2 hPa) set on the subscale so that the altimeter indicates the intended reference, such as elevation, height or flight level.

The ratio of total lift to aircraft weight; it increases in turns and manoeuvres and determines the structural stress placed on the airframe.

The speed above which full or abrupt control deflection can overstress the airframe, so controls must be applied smoothly to avoid exceeding the design load factor.

The lowest indicated airspeed at which an aeroplane can maintain level flight in a given configuration; it rises with weight, load factor and forward centre of gravity.

The angle between the wing chord line and the relative airflow; lift increases with it until the critical angle, beyond which the wing stalls.

The angle of attack at which airflow separates from the wing and lift drops sharply; an aeroplane stalls whenever this angle is reached, regardless of speed or attitude.

The point through which the total weight of the aircraft acts; its position affects stability, stall behaviour, cruise performance and the ability to recover from a spin.

The calculation confirming that the loaded aircraft's mass and centre of gravity position lie within the limits stated in the flight manual for the planned flight.

The mass of the aircraft including crew, passengers, baggage and usable fuel excluded; it must not exceed the maximum zero fuel mass certified for the type.

The total mass of the aircraft at the start of the take-off run, comprising zero fuel mass plus usable fuel, and limited by the maximum certified take-off mass.

Pressure altitude corrected for non-standard temperature; high density altitude reduces engine power, propeller thrust and wing lift, lengthening take-off and reducing climb performance.

The altitude indicated when the altimeter subscale is set to 1013.2 hPa; it is the reference used for performance charts and flight levels.

A condition in which body tissues receive insufficient oxygen; symptoms include euphoria, impaired judgement and cyanosis, and they worsen insidiously with increasing altitude.

The period after loss of oxygen supply during which a person can still take effective corrective action, shortening rapidly as altitude increases above 10,000 feet.

A false perception of the aircraft's position or motion caused by misleading vestibular and visual cues, most likely in cloud or at night without a stable visual horizon.

A false sensation of pitching up or down caused by linear acceleration or deceleration, which can lead a pilot to make inappropriate control inputs after take-off or during a go-around.

Abnormally rapid breathing that lowers blood carbon dioxide, causing dizziness, tingling and confusion that can resemble hypoxia and is often provoked by stress or anxiety.

The altimeter subscale setting that makes the instrument read aerodrome elevation when the aircraft is on the ground, giving altitude above mean sea level in flight.

The altimeter subscale setting that makes the instrument read zero on the aerodrome, so the pilot sees height above that aerodrome rather than altitude above sea level.

Standard pressure 1013.2 hPa used as the altimeter setting above the transition altitude, so that all aircraft share a common pressure datum for flight levels.

The temperature to which air must be cooled at constant pressure and moisture content for saturation to occur; a small temperature-dew point spread indicates high humidity and fog risk.

The altitude at which the air temperature reaches 0 degrees Celsius; above it, supercooled water and airframe icing become possible in cloud or precipitation.

Ice formation in the carburettor venturi caused by fuel vaporisation and pressure drop, most likely at temperatures between about -10 and +25 degrees Celsius with high humidity.

The angular difference between true north and magnetic north at a given place, applied when converting between true and magnetic headings on charts and in navigation calculations.

The error in a magnetic compass caused by the aircraft's own magnetic fields; it varies with heading and is recorded on a compass correction card.

The direction in which the aircraft's longitudinal axis points, measured clockwise from a chosen north reference and expressed in degrees.

Distance measuring equipment that provides slant range from the aircraft to a ground station, so the indicated distance is slightly greater than the horizontal distance at high altitude.

A ground-based navigation beacon transmitting radial information so that an equipped aircraft can determine its bearing from the station and track along a selected radial.

The mandatory repetition by the pilot of safety-related ATC clearances and instructions, such as route, level, heading and frequency, to confirm correct receipt.

The international radiotelephony distress signal, spoken three times, used when an aircraft is threatened by serious or imminent danger and requires immediate assistance.

The international radiotelephony urgency signal, spoken three times, used for a condition concerning safety that does not require immediate distress action.

The system of pressure sources and lines that supplies total pressure from the pitot tube and static pressure from the static ports to the airspeed indicator, altimeter and vertical speed indicator.

A blockage of the pitot head, often by ice or insects, that causes the airspeed indicator to behave like an altimeter, showing increasing speed in a climb and decreasing speed in a descent.

The ratio of true airspeed to the local speed of sound; it increases with altitude for a given true airspeed and matters for high-speed aeroplanes and jet operations.