Brunei DCA CPL(A) Operational Procedures key terms

The point during a flight where the crew must decide whether to continue to destination or divert. It is calculated so fuel remains sufficient for the chosen alternative plus reserves.

Fuel set aside for unforeseen factors such as weather, routing or traffic delays. It is normally a percentage of trip fuel or a fixed time increment, and is protected until genuinely needed.

The minimum fuel that must remain on landing, intended for holding and a safe approach. It is not available for normal planning and is only used in an emergency.

An aerodrome to which a flight may proceed if landing at the intended destination becomes impossible or inadvisable. It must meet weather, runway and fuel requirements at the planning stage.

A statement to air traffic control that the aircraft is committed to landing at a specific aerodrome and cannot accept undue delay. It is not an emergency but warns that further holding may lead to one.

Fuel allowance for engine start, taxiing and auxiliary power unit use before take-off. It is subtracted from total fuel when calculating take-off fuel and varies with aerodrome layout.

Total fuel loaded before flight, comprising taxi, trip, contingency, alternate and reserve fuel plus any extra. It is recorded on the load sheet and compared with actual consumption.

The part of an aerodrome used for surface movement of aircraft, comprising the manoeuvring area and aprons. Access is controlled, and unauthorised entry requires a specific clearance.

The portion of the aerodrome used for take-off, landing and taxiing, excluding aprons. Aircraft entering it need clearance from the aerodrome control tower.

The defined area on a land aerodrome where aircraft are parked for boarding, loading, refuelling or maintenance. Movement on the apron is often governed by marshallers or local procedures rather than ATC.

A trained person who gives standard hand signals to guide an aircraft on the apron, especially during parking. Pilots must follow marshalling signals unless safety requires otherwise.

A designated position where a taxiing aircraft must stop and await clearance before entering or crossing a runway. It is marked by specific signs and surface markings.

Any unauthorised presence of an aircraft, vehicle or person on a protected runway area. It is a serious safety event and a common cause of collisions on the ground.

An air traffic control instruction permitting an aircraft to enter the runway and position for take-off, but not to begin the take-off roll. A separate take-off clearance is required.

Authorisation from air traffic control to begin the take-off roll on a specified runway. It is distinct from line-up clearance and must be read back correctly.

A published departure route linking the runway to the en-route structure, including track, altitude and speed requirements. It simplifies clearance delivery and reduces controller workload.

A published route from the en-route structure to a point where approach clearance is given. It specifies tracks, altitudes and speed constraints for arriving traffic.

The altitude at or below which the aircraft flies with reference to local pressure settings and above which it uses standard pressure. It varies by state and is published on charts.

The lowest flight level available for use above the transition altitude. The layer between them is the transition layer, where vertical position references change.

The pressure value set on the altimeter subscale, either local QNH or standard pressure. Correct setting is essential for terrain clearance and vertical separation.

A pilot's repetition of an air traffic control clearance or instruction to confirm correct reception. Safety-critical items such as runway, altitude and heading must always be read back.

The point to which an aircraft is authorised to proceed under its current air traffic control clearance. Beyond it, a further clearance must be obtained.

A radio message giving the aircraft's location and related details, such as time, altitude and next position. It is required in areas without radar coverage.

A four-digit code entered in the transponder to identify the aircraft on secondary radar. Codes are assigned by air traffic control and must be set accurately.

The radio frequency 121.5 MHz used for distress and urgency communications. Pilots may use it when unable to establish contact on the assigned frequency.

The spoken distress signal indicating imminent danger requiring immediate assistance. It has absolute priority over all other transmissions and is repeated three times at the start of the call.

The spoken urgency signal used when a situation is serious but does not yet require immediate assistance. It has priority over routine traffic but ranks below distress.

A discontinued approach followed by a climb, used when landing cannot be completed safely. It may be initiated by the crew or instructed by air traffic control.

A published sequence of turns and climbs followed if an approach cannot be completed. It protects terrain clearance and positions the aircraft for another approach or diversion.

An approach in which the aircraft is on the correct path, speed and configuration by a defined height. Failure to meet the criteria normally requires a go-around.

The minimum visibility and cloud conditions permitting a pilot to take off or land at a given aerodrome. They depend on aircraft equipment, crew qualification and published procedures.

Ice accumulation on aircraft surfaces during flight in visible moisture at sub-zero temperatures. It degrades lift and increases drag, requiring prompt use of anti-ice or de-ice systems.

The altitude at which the outside air temperature is zero degrees Celsius. It indicates where icing is likely and is used when planning altitudes and fuel.

A sudden change in wind speed or direction over a short distance, often near thunderstorms or fronts. It can cause severe airspeed fluctuations close to the ground.

A manoeuvre keeping an aircraft within a specified airspace while awaiting further clearance. It follows a published pattern with defined legs, turns and timing or distance.

The runway length required so that a failure at the critical engine speed allows either a stop or a continued take-off within the available distance. It determines the maximum permitted take-off mass.

The decision speed at which the pilot must either continue the take-off or stop. It is calculated for each take-off and is central to performance planning.

The calculation of distances, speeds and climb gradients for a given mass, temperature, pressure altitude and wind. It ensures obstacles and runway limits are respected.

The point where the aircraft's total weight is considered to act. It must remain within the certified forward and aft limits for controllability and performance.

A document showing the aircraft's mass, distribution and centre of gravity position before departure. It is signed by the responsible person and must match the actual loading.

The process of ensuring the aircraft's weight and centre of gravity stay within certified limits for the intended flight. It affects take-off, climb, cruise and landing performance.

A framework in which crews identify external threats and their own errors, then apply countermeasures to prevent an undesired aircraft state. It is central to line operations safety.

The effective use of all available resources, including crew, equipment and information, to achieve safe flight. It covers communication, leadership, workload management and decision making.

A rule prohibiting non-essential activity or conversation during critical phases such as taxi, take-off and approach. It reduces distraction when workload is highest.