A to Z of Aviation Terminology - (A)

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"Abeam" refers to a position of an aircraft or an object that is 90 degrees to the left or right of an aircraft's heading. It is used as a reference for pilots to communicate the position of other aircraft or landmarks relative to their own aircraft.
Absolute altitude refers to the height of an aircraft above mean sea level (MSL). It is expressed in feet or meters and provides a reference point that is independent of local terrain or pressure conditions. Absolute altitude is used by pilots and air traffic controllers to ensure safe separation between aircraft at different altitudes and is a key parameter in determining the flight level of an aircraft.
Absolute ceiling refers to the maximum altitude an aircraft can reach under standard atmospheric conditions and still maintain level flight. It is expressed in feet or meters above mean sea level (MSL). The absolute ceiling is determined by the power available from the aircraft's engine and the aerodynamic design of the aircraft. Beyond this altitude, the aircraft would no longer be able to maintain level flight and would start to descend. The absolute ceiling is an important consideration for pilots, especially when flying over mountainous terrain.
Adverse yaw is a phenomenon that occurs in aircraft when the aircraft's yaw (the rotation around the vertical axis) moves in the opposite direction from the desired turn. This can happen when the pilot applies aileron (the control surface used to roll the aircraft) to initiate a turn, causing one wing to rise and the other to descend.

When the aircraft starts to turn, the descending wing generates more lift than the rising wing, creating a yawing moment that tends to move the nose of the aircraft away from the direction of the turn. This is adverse yaw.

Adverse yaw can be compensated for by applying rudder (the control surface used to yaw the aircraft) in the direction of the turn, which balances the yawing moment and helps the aircraft to follow the desired flight path. The amount of rudder required to compensate for adverse yaw will depend on the design of the aircraft and the speed at which it is flying.

Adverse yaw is an important factor for pilots to understand, as it can affect the stability and control of the aircraft, particularly during takeoff and landing. To minimize adverse yaw, aircraft designers use a variety of techniques, including designing the wing with a washout (a gradual reduction in angle of attack from the wingtips to the roots), using winglets to reduce the wingtip vortices, and designing the ailerons to be more effective.

Overall, adverse yaw is a normal and predictable phenomenon that pilots learn to anticipate and manage as part of their training. With experience and proper training, pilots can effectively control their aircraft and fly safely, even in adverse yaw conditions.
Aerial refuelling is the process of transferring fuel from one aircraft to another while both are in flight. It is used to extend the range of aircraft, especially military aircraft, by allowing them to refuel in mid-air without landing. Aerial refuelling can be accomplished in various ways, including the use of a boom attached to the refuelling aircraft or the use of a hose and drogue system that extends from the refuelling aircraft and is received by the receiving aircraft. Aerial refuelling is a complex and potentially dangerous operation that requires precise coordination between the two aircraft and highly trained personnel.
An aeronautical chart is a map specifically designed for use by pilots and air traffic controllers. It provides information on airspace, terrain, navigation aids, and other features relevant to aviation. Aeronautical charts can be divided into several categories, including en route charts, terminal area charts, and approach procedure charts. Enroute charts provide information for flight planning and navigation during the en route phase of flight, while terminal area and approach charts provide detailed information for the approach and landing phases of flight. Aeronautical charts are an essential tool for pilots, providing information necessary for safe and efficient navigation.
AGL stands for Above Ground Level, which refers to the altitude of an aircraft relative to the terrain or ground level directly below it. It is expressed in feet or meters and is used in contrast to MSL (mean sea level) altitude, which provides a reference point that is independent of local terrain or pressure conditions. AGL altitude is important for flight operations near the ground, such as takeoff, landing, and low-altitude navigation, and is used by pilots, air traffic controllers, and other aviation professionals to ensure safe flight operations and terrain clearance.
Ailerons are control surfaces located on the trailing edge of an aircraft's wings. They are used to control the roll or banking of the aircraft and are typically moved in opposite directions to create a difference in lift between the wings and cause the aircraft to roll. Ailerons are an important part of an aircraft's flight control system and play a critical role in maintaining stability and manoeuvrability during flight. When a pilot moves the control wheel or stick, signals are sent to the ailerons, which then move to cause the aircraft to roll. Ailerons are commonly used in both fixed-wing aircraft and some types of rotary-wing aircraft.
Air ambulance is a type of aircraft that is specifically designed or equipped for emergency medical transportation. Air ambulances are used to transport patients who are critically ill or injured from one location to another, usually to a hospital with higher levels of care. Air ambulances can be equipped with medical equipment, such as oxygen, IV pumps, and ventilators, and staffed with trained medical personnel, such as paramedics, nurses, and physicians, to provide care during transport. Air ambulance flights are usually coordinated by specialized air ambulance companies, and are used in a variety of scenarios, including trauma, heart attacks, strokes, and other medical emergencies. Air ambulance is an important component of the emergency medical services (EMS) system and plays a critical role in saving lives and improving patient outcomes.
Air charter is the business of renting an entire aircraft or a portion of an aircraft to a client for a specific purpose or trip. Air charter allows individuals or organizations to bypass the scheduling and route restrictions of commercial airlines and to have a more customized and flexible air travel experience. Air charter companies provide a range of aircraft, from single-engine propeller planes to large corporate jets, to meet the specific needs of their clients. The cost of air charter is typically higher than commercial air travel, but the added flexibility and convenience can be worth the premium for many clients. Air charter is commonly used for business travel, VIP travel, sports teams, medical evacuation, and other specialized needs.
An air charter operator is a company or organization that provides air charter services. An air charter operator operates one or more aircraft and offers these aircraft for rent to clients for a specific purpose or trip. The clients can choose the aircraft type and the route, and the air charter operator will arrange the flight to meet their specific needs. An air charter operator must comply with all relevant aviation regulations, including those related to aircraft maintenance, pilot training and qualifications, and insurance. The air charter operator is responsible for ensuring the safe and efficient operation of the aircraft and must meet the standards set by aviation authorities such as the Federal Aviation Administration (FAA) in the United States. Some air charter operators focus on a specific market segment, such as business travel or VIP travel, while others offer a range of aircraft for a variety of purposes.
An air taxi is a type of small aircraft used for on-demand air transportation, often over short distances. Air taxis are similar to taxi cabs in that they offer point-to-point transportation, but they do so by air rather than by road. Air taxis are typically small, single-engine or turboprop aircraft that are operated by a pilot, and they offer a flexible and convenient alternative to commercial airlines, particularly for travellers who need to reach smaller or remote airports. Air taxis typically have a lower capacity and a higher cost per passenger than commercial airlines, but they offer a more personal and customized travel experience. Air taxis are often used by business travellers, tourists, and others who need to reach their destination quickly and efficiently, or who are travelling to remote locations that are not served by commercial airlines.
Air Traffic Control (ATC) is a system responsible for ensuring the safe, orderly and efficient management of aircraft in the airspace. It manages flight plans, ensures separation between aircraft and provides navigation assistance to pilots.
An aircraft is a machine that is capable of flight, typically through the use of engines, wings, and a fuselage. This includes planes, helicopters, gliders, hot air balloons, and other flying machines.
Aircraft management refers to the process of overseeing and coordinating all aspects of operating an aircraft, including maintenance, flight scheduling, crew management, regulatory compliance, and budgeting. The goal of aircraft management is to ensure safe, efficient, and cost-effective operation of the aircraft.
Aircraft positioning refers to the movement of an aircraft from one location to another, either on the ground or in the air. This includes positioning for maintenance, repositioning for a new flight, or positioning to a storage location when the aircraft is not in use. The goal of aircraft positioning is to ensure the aircraft is in the right place at the right time to support its intended use.
An airfoil is a structure with a curved surface, that generates lift when moved through a fluid, such as air. In aviation, airfoils are used for the wings of aircraft to provide lift and enable flight. The shape of an airfoil is designed to cause a difference in air pressure between the upper and lower surfaces, creating lift.
An Airport Operator Certificate (AOC) is a document issued by a national aviation authority that certifies an airport operator has met the necessary safety, security and operational standards to operate an airport. The AOC is required for airports to legally operate and provides a framework for the management, administration and control of the airport facilities, operations and services. It also serves as evidence of the airport operator's commitment to meeting international safety and security standards and regulations.
An airport is a complex of facilities and runways designed to support the takeoff, landing, and maintenance of aircraft. Airports are typically located near cities or other populated areas and serve as hubs for air travel and commerce.

Airports typically include several key components, including runways, taxiways, hangars, terminals, and control towers. The runways are the surfaces on which aircraft take off and land, and the taxiways provide a means for aircraft to move between the runways and the terminals. Hangars are buildings where aircraft can be stored and maintained, while terminals are buildings where passengers can check-in, wait for their flights and board the aircraft. The control tower is the central location from which air traffic control personnel direct and monitor aircraft movement on the airport grounds.

Airports also provide support services for aircraft and passengers, including fuel and maintenance services, ground handling and ramp services, food and beverage concessions, and baggage handling and storage. In addition, airports may offer other amenities, such as lounges, shopping and dining options, and transportation services to and from the airport.

Airports play a vital role in connecting people and goods, and they are an essential component of modern transportation systems. With the growth of air travel, airports have become complex and sophisticated operations that require careful planning, design, and management to ensure efficient and safe operations.
An Air Operator Certificate (AOC) is a document issued by a national aviation authority, certifying an airline to operate commercial flights. The certificate verifies that the airline meets relevant safety standards, regulatory requirements, and other standards specified by the aviation authority. An AOC is required for an airline to legally operate commercial flights and is considered essential for the continued and safe operation of the airline. The AOC process involves a comprehensive evaluation of the airline's operational and management systems, personnel, aircraft, maintenance procedures, and other critical areas.
An Airport Reservation Office (ARO) is a location where customers can make flight reservations and purchase tickets for airlines. AROs may be physical offices located at airports or they may be call centers or online platforms operated by airlines or travel agencies. AROs are typically staffed by customer service representatives who assist customers with flight reservations, ticket purchases, seat assignments, and other related services. The primary function of an ARO is to facilitate the booking and ticketing process for customers, ensuring that they are able to make the necessary arrangements for their travels.
Airspace classes are designations used by aviation authorities to define and regulate the use of airspace. There are seven different airspace classes (A-G) with specific rules and regulations for each. These classes determine the level of control and restrictions on aircraft operations in a given airspace.

Here is a brief overview of the seven airspace classes:

A - Controlled airspace that is generally reserved for commercial and military operations, with the highest level of control and restriction on aircraft operations.

B - Controlled airspace around busy airports, with a medium level of control and restriction on aircraft operations.

C - Controlled airspace around smaller airports, with a lower level of control and restriction on aircraft operations.

D - Controlled airspace around some smaller airports, with varying levels of control and restriction on aircraft operations.

E - Controlled airspace for Instrument Flight Rules (IFR) operations, typically at higher altitudes.

F - Advisory airspace, where flight information service is provided but without control of aircraft operations.

G - Uncontrolled airspace, where no flight information service is provided and aircraft are free to operate without specific restrictions.

It is important for pilots to understand the specific rules and regulations associated with each airspace class, as they will have an impact on their flight operations.
Airspeed is the speed of an aircraft relative to the air mass through which it is moving. It is important for navigation and aircraft performance, as it affects lift, fuel consumption, and many other factors. Airspeed is usually measured in knots, kilometers per hour, or miles per hour.
Airway distance refers to the shortest navigable route between two points in the air. It is used by air traffic controllers and pilots to plan flights and ensure safe navigation. The airway distance is calculated based on established flight paths, taking into account terrain, weather, and other factors that may affect the flight. It is typically measured in nautical miles and is different from a great-circle distance, which is the shortest distance between two points on the earth's surface.
An Airworthiness Directive (AD) is a notice issued by aviation regulatory authorities, such as the Federal Aviation Administration (FAA) in the United States or the European Aviation Safety Agency (EASA), to address an unsafe condition in an aircraft type or product and to require actions to correct the condition. ADs are typically issued for aircraft, engines, propellers, and other aircraft components and systems and are mandatory for compliance. The purpose of an AD is to ensure the continued airworthiness and safety of the aircraft and its components, and failure to comply with an AD can result in serious consequences for the aircraft operator. ADs can be initiated by the manufacturer, regulatory authorities, or even by a single operator, and are usually issued after a safety investigation or as a result of mandatory reporting requirements.
An alternate airport, also known as a diversion airport, is a backup airport that a pilot can land at if they are unable to reach the planned destination airport due to weather or other conditions that make landing unsafe or impossible. Alternate airports are part of flight planning and are chosen based on their availability, location, weather conditions, and the aircraft's fuel range. The pilot must have enough fuel on board to reach the alternate airport and still have a reserve of fuel in case of unexpected events, such as headwinds or deviations from the planned flight path. The availability of an alternate airport is a critical factor in flight planning and is closely monitored by air traffic controllers and the flight crew throughout the flight.
An altimeter is an instrument that measures the altitude of an aircraft above a reference level, usually mean sea level. It works by measuring the atmospheric pressure and converting it into an altitude reading. Altimeters are essential for navigation and provide pilots with information about the aircraft's vertical position, which is crucial for flying at the correct altitude, avoiding terrain, and ensuring a safe landing. There are two types of altimeters: barometric and radio. Barometric altimeters measure atmospheric pressure to determine altitude, while radio altimeters use radio waves to measure the distance between the aircraft and the ground. Both types of altimeters are commonly used in aviation and provide critical information for flight safety.
Altitude is the height of an object, such as an aircraft or a mountain, above a reference level, usually mean sea level. In aviation, altitude is a crucial aspect of flight and is used for navigation, performance calculation, and to avoid obstacles and other aircraft. Altitude is usually measured in feet or meters and is reported in terms of indicated altitude, which is what is displayed on the aircraft's altimeter, and true altitude, which is the actual height above sea level. The difference between the two can be significant and is caused by atmospheric pressure and temperature variations. Pilots and air traffic controllers use altitude information to ensure safe flight and separation between aircraft, and it is a key factor in flight planning and execution.
Amphibious floats are devices attached to an aircraft's landing gear to allow it to operate on both land and water. They are designed to provide flotation and stability for the aircraft while on water and also have wheels that can be extended or retracted for landing and takeoff on land. Amphibious floats are commonly used on seaplanes, floatplanes, and amphibious aircraft and are used to access remote areas and lakes where there are no airports. The floats provide the aircraft with the ability to take off and land on water, making them ideal for search and rescue missions, transporting people and goods, and conducting surveillance operations. They are typically made of lightweight materials, such as aluminum or composites, to minimize their impact on the aircraft's performance and weight.
The angle of attack (AOA) is the angle between the chord line of an aircraft's wing and the relative wind direction. The chord line is a straight line that runs from the leading edge to the trailing edge of the wing, and the relative wind direction is the direction of the airflow relative to the wing. The angle of attack is an important factor in determining the lift generated by an aircraft's wing, as well as its stability and control. A high angle of attack can cause the airflow over the wing to separate, resulting in a loss of lift and an increased risk of a stall. A low angle of attack can result in an insufficient lift, making it difficult for the aircraft to maintain altitude. Pilots must carefully monitor the angle of attack during flight and make adjustments to maintain optimal performance and avoid dangerous conditions.
Anhedral is a term used in aviation to describe the downward angle of an aircraft's wings relative to the horizontal plane of the aircraft's fuselage. An aircraft with anhedral wings has its wings angled downward from the root to the tip, rather than being level or angled upward.

Anhedral is used to reduce the lift generated by the wings during low-speed flight, which helps to increase stability and prevent the aircraft from entering a stall. Anhedral also reduces the risk of wing tip stalls, which can cause an aircraft to roll or yaw unpredictably.

Anhedral is often used in aircraft designs that require low-speed stability and handling, such as gliders, light sport aircraft, and unmanned aerial vehicles (UAVs). The design of anhedral wings can vary widely, depending on the aircraft's intended use and operating conditions. Some aircraft have wings that are angled downward only slightly, while others have wings that are angled downward by several degrees.
Approach and Departure Control (ADC) is a type of air traffic control service that manages aircraft as they approach and depart from an airport. ADC is responsible for ensuring safe and efficient operations in the airspace surrounding the airport and for coordinating arrivals and departures with other air traffic control services, such as the tower control and the en-route control center. The approach and departure controllers use radar and other equipment to monitor aircraft movements, provide guidance to pilots, and ensure that aircraft are properly spaced and sequenced for landing and takeoff. They also provide information to pilots on weather conditions, altitude restrictions, and other factors that may affect their flight. ADC is a crucial component of the air traffic control system and plays a critical role in ensuring the safe and efficient operation of the world's airports.
An Approach Light System (ALS) is a lighting system installed at an airport to provide visual guidance for aircraft during their approach to landing. The system is designed to help pilots accurately align the aircraft with the runway centerline and to provide visual cues for determining the correct descent path to the runway. ALS can consist of a variety of lights, including low-intensity runway lights, sequenced flashing lights, and high-intensity runway lights, and can be combined with other visual aids, such as a precision approach path indicator (PAPI) or a visual approach slope indicator (VASI). The type and configuration of the ALS depend on the type of runway and the approach environment and is selected to provide the best combination of visual guidance and safety for aircraft. The ALS is an essential component of the airport's lighting system and plays a critical role in ensuring safe and efficient operations at the airport.
Approach speed is the speed at which an aircraft descends and approaches the runway for landing. It is a critical factor in determining the aircraft's performance and safety during landing, and is determined based on factors such as the aircraft's weight, configuration, and wind conditions. Approach speed is typically specified by the manufacturer and is used by pilots to determine the correct landing configuration, such as flaps and landing gear extension, to ensure a safe and stable approach and landing. The approach speed must be carefully monitored by the pilot during the landing process and adjusted as necessary to maintain the correct flight path and landing stability. If the approach speed is too high, the aircraft may float or overshoot the runway, while if it is too low, the aircraft may stall or touch down too far down the runway, which can be dangerous. Approach speed is a critical aspect of flight safety and must be managed carefully to ensure a safe and successful landing.
An apron is an area of an airport adjacent to the terminal buildings and hangars where aircraft are parked, loaded and unloaded, refueled, and serviced. The apron is usually made of concrete or asphalt and is designed to withstand the weight and movement of aircraft. The apron is divided into parking stands or gates, where aircraft can be parked and accessed by passengers and crew. The apron also contains refueling and de-icing trucks, baggage carts, and other ground service equipment. The apron is a busy and controlled area, and access to it is restricted to authorized personnel only. The apron is a critical component of an airport and plays a crucial role in the efficient operation of the airport by facilitating the movement of aircraft and passengers.
ARGUS (Automated Real-time Ground Surveillance) is a technology used in air traffic control and airport security to enhance situational awareness and improve the safety and efficiency of flight operations. ARGUS uses multiple sensors and cameras to create a real-time, 360-degree view of the airport environment, including the runways, taxiways, and apron areas. The system integrates and processes the data from these sensors to provide a comprehensive view of all aircraft and ground vehicle movements, allowing air traffic controllers and airport security personnel to detect potential threats and respond to emergencies more quickly and effectively. ARGUS also provides a valuable tool for aircraft tracking and management, helping to improve the efficiency of airport operations by reducing congestion and delays. ARGUS is widely used in the aviation industry and has become a critical component of modern air traffic control and airport security systems.
An autogiro, also known as a gyroplane or gyrocopter, is a type of aircraft that uses an unpowered rotor to generate lift and a powered propeller to generate forward thrust. The autogiro was developed in the 1920s as a precursor to the helicopter and is considered to be a unique and hybrid type of aircraft, combining features of both fixed-wing aircraft and rotary-wing aircraft.

An autogiro operates differently from a helicopter, as the rotor generates lift in a passive manner, relying on airflows generated by the forward motion of the aircraft to keep the rotor turning. The powered propeller provides the forward thrust to keep the aircraft moving and allows it to climb and descend.

Autogiros have been used for a variety of purposes, including military reconnaissance and observation, agricultural spraying, and personal transportation. However, the widespread adoption of helicopters has largely relegated the autogiro to a niche role in aviation history, and it is now used primarily for recreational purposes.
Automated Surface Observing System (ASOS) is a network of automated weather stations located at airports across the United States. The system provides up-to-date weather information, including temperature, dew point, wind speed and direction, visibility, cloud cover, and precipitation. The data collected by ASOS is used by aviation organizations, weather forecasters, and the general public to help make informed decisions regarding travel and outdoor activities. ASOS is maintained by the National Weather Service and replaces human-observed weather stations to provide more comprehensive and frequent weather observations.
Automatic Terminal Information Service (ATIS) is a continuously looped recorded broadcast of up-to-date information specific to an airport, including weather information, active runways, and any other pertinent details to aid pilots during their approach, landing and takeoff phases. ATIS is intended to help reduce the workload on air traffic control (ATC) and provide consistent and accurate information to pilots in real-time.
Aviation refers to the operation of aircraft to provide transportation of goods and people, as well as military, scientific, and recreational activities. It encompasses the design, manufacturing, maintenance, and use of aircraft, and the infrastructure and organizations necessary for air navigation and air traffic control. The development of aviation has had a profound impact on the world, enabling faster and more efficient travel, commerce, and communication, as well as advancing military capabilities and scientific research. Aviation continues to evolve, with new technologies and innovations leading to the development of more efficient and environmentally friendly aircraft.
Avionics refers to the electronics and technology used in the design and operation of aircraft. This term covers a wide range of systems including navigation, communication, flight control, weather radar, and displays. Avionics technology has advanced significantly in recent years and plays an important role in the safety, efficiency, and performance of modern aircraft. The integration of avionics systems with flight management systems, navigation databases, and other on-board computers has resulted in the development of sophisticated aircraft that are able to fly more accurately and safely, even in adverse weather conditions.
The avionics master switch is a switch or circuit breaker that provides centralized control over the electrical systems that operate the aircraft's avionics and communications equipment. The avionics master switch is typically located in the cockpit of the aircraft and provides a single point of control for turning on and off the various avionics systems, including the radios, navigation equipment, instruments, and displays.

The avionics master switch is an important safety feature in aviation, as it allows the pilot to quickly and easily shut down all of the aircraft's avionics systems in the event of an emergency, such as an electrical failure or a fire. By turning off the avionics master switch, the pilot can isolate the electrical systems from the aircraft's batteries, reducing the risk of electrical arcing or fire.

In modern aircraft, the avionics master switch may be incorporated into a more comprehensive electrical power distribution system, allowing the pilot to control the distribution of power to individual systems or sub-systems as needed. The avionics master switch may also be integrated into the aircraft's emergency procedures, providing a simple and straightforward way for the pilot to respond to emergency situations and ensure the safety of the aircraft and its occupants.

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