Bahrain CAA ATPL Theory key terms

The speed by which a failure of the critical engine must have been recognised so that the pilot can either continue the take-off or stop the aircraft on the remaining runway. It is determined before take-off from mass, runway and atmospheric data.

The minimum speed that must be reached by 35 feet above the runway surface with one engine inoperative, ensuring adequate climb gradient and control. It is maintained until sufficient height allows acceleration and flap retraction.

The runway length at which the distance needed to accelerate and stop after an engine failure equals the distance needed to continue the take-off and reach 35 feet. It represents the most limiting field length for a given mass.

The certified forward and aft limits within which the aircraft's centre of gravity must lie for every phase of flight. Exceeding forward limits increases stick forces and landing distance; exceeding aft limits reduces static stability.

The chord of an equivalent rectangular wing that has the same area and pitching moment characteristics as the actual wing. CG position is often expressed as a percentage of MAC for loading and control calculations.

The mass of the aircraft including structure, powerplant, systems, unusable fuel, and all operating fluids and equipment required for flight, but excluding crew, passengers, payload and usable fuel. It is the starting point for all mass and balance calculations.

The mass of the aircraft with all payload and crew but without usable fuel. It is compared against a maximum certified value because structural limits apply regardless of how much fuel is carried.

The initial tendency of an aircraft to return to its original equilibrium state after a disturbance. Positive static stability aids handling and reduces pilot workload, while negative static stability makes control difficult or dangerous.

The angle of attack at which the wing reaches maximum lift coefficient and beyond which airflow separates, causing a stall. It is independent of mass, bank angle and airspeed, though those factors change the speed at which it is reached.

The tendency of an aircraft with upward-angled wings to roll away from a sideslip, contributing lateral stability. Too much dihedral can cause Dutch roll and spiral instability, so it is balanced against directional stability.

The ratio of true airspeed to the local speed of sound. It governs compressibility effects such as shock-wave formation, Mach tuck and buffet margins, and is a primary limit at high altitude.

The narrow band of airspeed and altitude at which the low-speed stall margin and the high-speed Mach buffet margin converge. Flying within it leaves almost no tolerance for turbulence or manoeuvre.

The actual speed of the aircraft through the surrounding air mass, corrected for air density and compressibility. It is used for navigation and for determining Mach number and aerodynamic margins.

The speed shown on the airspeed indicator before correction for position error, density and compressibility. It is the primary reference for handling, stall margins and structural limits because it reflects dynamic pressure.

The network of pressure probes 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. Blockages produce characteristic instrument errors.

The reference pressure dialled into a barometric altimeter so that it indicates the intended datum, such as mean sea level or standard pressure. Using the wrong setting compromises terrain clearance and vertical separation.

The altitude above which pilots set standard pressure and fly at flight levels, and below which they use local pressure settings. It is published for each aerodrome or area and marks the boundary between altimeter and flight-level references.

The lowest flight level available for use above the transition altitude, ensuring at least the required separation between aircraft flying on standard pressure and those using local pressure. It varies with atmospheric pressure.

An airspace designation permitting 1,000-foot vertical separation between suitably equipped aircraft between specified flight levels. Operators require approval, specific altimetry equipment and height-keeping performance monitoring.

The convention assigning magnetic cruising levels according to track direction, with eastbound tracks using odd levels and westbound tracks using even levels. It provides systematic vertical separation between opposing traffic flows.

An authorisation from air traffic control for an aircraft to proceed under specified conditions. It does not relieve the pilot in command of responsibility for terrain clearance, wake turbulence separation or compliance with regulations.

The mandatory repetition by the pilot of safety-related clearance elements such as route, level, speed and frequency, allowing the controller to verify correct reception. Failure to read back correctly is a major source of communication error.

The prescribed wording used in radiotelephony to convey clearances and information unambiguously. Deviation from it increases misunderstanding risk, particularly with non-native speakers or poor radio quality.

A radio message giving an aircraft's identification, position, time, level and next reporting point. It allows controllers to maintain separation in procedural or low-coverage airspace without radar.

The shortest path between two points on the surface of a sphere, lying on a plane passing through the Earth's centre. It is used for long-distance navigation because following it minimises fuel and time.

A line of constant track that crosses every meridian at the same angle, appearing straight on a Mercator chart. It is longer than a great circle except along meridians and the equator, but simplifies constant-heading navigation.

The angle at which meridians meet, equal to the difference in longitude multiplied by the sine of the latitude. It is used to convert between true and grid or magnetic directions over long distances.

A ground-based navigation aid transmitting signals that allow an aircraft to determine its magnetic bearing from the station. Radial information supports route navigation, position fixing and instrument approach procedures.

A transponder-based system measuring slant range between the aircraft and a ground station by timing signal exchanges. The indication exceeds true ground distance by an amount depending on altitude and range.

A precision approach aid providing lateral guidance from a localiser and vertical guidance from a glide path, together with distance and marker information. It supports approaches to low decision heights in poor visibility.

The altitude at which a missed approach must be initiated if the required visual reference has not been established. For precision approaches it is referenced to a barometric altimeter, unlike decision height which uses radio height.

The lowest altitude permitted during a non-precision approach before the required visual reference is acquired. Descent below it is only allowed once the runway environment is clearly visible.

A condition in which body tissues receive insufficient oxygen, causing impaired judgement, euphoria and loss of consciousness. It can occur from altitude exposure, decompression or equipment failure and is insidious in onset.

The period after loss of cabin pressure during which a person can still take effective corrective action before incapacitation. It shortens rapidly with increasing altitude and is used to plan oxygen and descent procedures.

A false perception of the aircraft's position or motion relative to the Earth, often arising when visual references are lost and vestibular cues mislead. It is countered by instrument cross-checks and disciplined scan techniques.

A false sensation of pitching up or down caused by linear acceleration or deceleration stimulating the inner ear. It can lead a pilot to push forward after take-off acceleration, with dangerous loss of height.

The temperature to which air must be cooled at constant pressure for water vapour to condense into liquid water. A small spread between temperature and dew point indicates high humidity, fog risk and possible carburettor icing.

The rate at which temperature decreases with increasing height in the atmosphere. The standard atmosphere uses about 2 degrees Celsius per 1,000 feet, and deviations affect aircraft performance and altimeter accuracy.

Ice formation in a carburettor caused by fuel vaporisation and pressure reduction cooling the air, most likely at temperatures between about minus 10 and plus 20 degrees Celsius with high humidity. It can cause rough running or engine failure.

A narrow, fast-moving band of strong winds near the tropopause, associated with large horizontal temperature gradients. It strongly affects ground speed, fuel planning and turbulence on long-haul routes.