If you wonder what some terms used in flight simulator or in the world of aviation in general mean, you should take a look below. Common used terms are in alfabetical order listed here.

Ailerons
Ailerons are mounted on the back edge of each wing near the wingtips, and move in opposite directions. The ailerons are used to bank the aircraft; to cause one wing tip to move up and the other wing tip to move down. When the stick is moved left to bank the airplane to the left, the right aileron is lowered which increases lift on the right wing and therefore increases drag on the right wing.

ATC
Air Traffic Control - A service provided by ground based controllers who direct aircraft on the ground and in the air to ensure safe, orderly and expeditious traffic flow.

Air brakes
Used on high speed aircraft and are intended to increase the drag of an aircraft without altering the amount of lift. Airbrakes and spoilers are often the same device, the combined spoiler/airbrakes act to simultaneously remove lift and to slow the aircraft's forward motion. Ground spoilers, which are a combination of airbrakes/flight spoilers along with additonal panels are deployed upon touchdown to assist braking the aircraft by applying positive downward forces which also ensures that the aircraft remains planted firmly on the ground.

Airspeed
Speed of the aircraft related to the air. True airspeed (TAS) is the real airspeed, independent of the wind speed and direction. Indicated airspeed (IAS) indicates the speed of the air around the aircraft, so it depends on the wind speed, direction and amount of air. IAS is the most important, since the gear and flap speed limits are in IAS.

Altimeter
The altimeter is an instrument which measures vertical distance with respect to a reference level. In an aircraft, the altimeter measures the altitude of the land surface or any object. The traditional altimeter found in most aircraft works in measuring the air pressure from a static port in the airplane. Air pressure decreases with an increase of altitude - about one millibar (0.03 inches of mercury) per 27 feet (8.23 m) close to sea level. For an accurate altitude indication, it has to be adjusted every time. In flight simulator, the ATC will give you the current altimeter setting. Press the B-key to reset the altimeter.

APU
An Auxiliary Power Unit (APU) is a self-contained generator powered with a small gas turbine engine usually located at the tail of an aircraft. Its purpose is to provide pneumatic and electric power to support aircraft operations. The pneumatic and electric power supports cabin conditioning and main engine starting during ground operations and emergency power for in-flight operation in case of a dead engine.

Callsign
Used in radio transmissions between the ATC and an aircraft. A callsign is in fact the name of the aircraft operator. With ATC transmission, the flight number is added to the callsign. In order to avoid confusion with a call sign used by an established airline, some call-signs are less obviously associated with a particular airline than others.

Contrails
Contrails are line-shaped clouds produced by aircraft engine exhaust, typically at aircraft cruise altitudes several miles above the earth's surface (upper atmosphere). The combination of water vapor in aircraft engine exhaust and the low ambient temperatures that often exists at these high altitudes allows the formation of contrails.

DME
Distance measuring equipment: In radio location systems, equipment that ascertains the distance between an interrogator and a transponder. Aircraft use DME to determine their distance from a land-based transponder by sending and receiving pulse pairs - two pulses of fixed duration and separation.

Elevators
An elevator is mounted on the back edge of the horizontal stabilizer on each side of the fin in the tail. They move up and down together. When the pilot pulls the stick backward, the elevators go up. Pushing the stick forward causes the elevators to go down. Raised elevators push down on the tail and cause the nose to pitch up. This makes the wings fly at a higher angle of attack which generates more lift and more drag. Centering the stick returns the elevators to neutral and stops the change of pitch.

Eyebrows
Small windows above the front windshield to help provide better crew visibility. It's a typical Boeing design and is used on the Boeing 707, 727 and 737 models. With today's advanced navigation systems, those windows are not longer relevant.

Flaps
Flaps are hinged surfaces on the trailing edge of an airplane wing which, when deployed, increase the lift (and drag) of a wing. They are usually used while landing to allow the aircraft to fly more slowly and to steepen the approach to the landing site. With takeoff, they create more lift in order to get airborne. Speed limits of each flap setting prevent damage of the flap construction

Flare
The flare is an aircraft landing manoeuvre where the rate of descent will be reduced by transitioning to a stall attitude. The trick is to reduce the amount of trust (or propeller speed) and at the same time bring the nose up. The higher pitch attitude will slow down the descent rate and at the same time make sure that the main landing gear will touchdown first.

FMC
Flight Management Computer. Used in commercial aircraft to input the flightplan and other data. This computer collects data from sensors in an aircraft, controls the autopilot and calculates load, fuel and more.

Heavy
A term that is used in radio transmissions between the ATC and an aircraft to describe that it's a large aircraft. It's added to the callsign and flighnumber like "Speedbird 744 Heavy". An aircraft is considered 'heavy' if an aircraft is capable of takeoff weights greater 255,000 lbs (115,666 kg) in the US (FAA standards) and 299,828 lbs (136,000 kg) in other parts of the world (ICAO standards). The purpose of the serperation into aircraft (weight) classes is the amount of wake turbulence produced by the wingtips. The jet engine exhaust/wash has nothing to do with wake turbulence. Adding the term 'heavy' to a callsign is a reminder to ATC to apply the apropriate wake turbulence separation standards when operating in the terminal area. In FS, the term 'heavy' should be added to any aircraft bigger than a 757 or A321.

Horizontal Stabilizer
The horizontal stabilizer or tailplane is a fixed or adjustable surface from which an elevator may be hinged. In some aircraft models, the entire horizontal stabilizer rotates and functions as an elevator.

IFR
IFR is the abbreviation for Instrument Flight Rules. These are a set of regulations and procedures for safety of flight in low visibility conditions using the instrument panel and navagation radios as the main reference for flight. Special rules apply to IFR flight as opposed to flight during VFR conditions. Such rules include the amount of fuel required to be onboard the aircraft. Since navigation and control of the aircraft under IFR is done by instruments, flying through clouds is allowed; under VFR it is not.

ILS
Instrument landing system - landing aid for aircraft that uses radio beacons on the ground and instruments on the flight deck. One beacon (localizer) sends out a vertical radio beam along the centre line of the runway. Another beacon (glide slope) transmits a beam in the plane at right angles to the localizer beam at the ideal approach-path angle. The pilot can tell from the instruments how to manoeuvre to attain the correct approach path, or let the autopilot manoeuvre the aircraft automatically on the correct approach path.

NATO phonetic alphabet
The international radiotelephony spelling alphabet. Used for many purposes, such as in ATC radio transmissions. In order to avoid confusion, standard words are assigned to each letter of the alphabet. That way, regardless of native languages, everybody is be able to understand eachother. Click here to view the NATO alphabet.

PAPI
Precision Approach Path Indicator. It's a light system positioned beside the runway that consists of two or four boxes of lights that provide a visual indication of an airplane's position on the glidepath for the associated runway. In the case of 4 lights, 4 red lights mean that you are below approach slope, 4 white lights mean that you are above approach slope, 2 red and 2 white mean that you are on approach slope.

Retard
This word is a callout in cockpit systems used in aircraft manufactured by Airbus. It's a reminder to pilots to bring the thrust levers to idle during the landing maneuver, just prior to touchdown. If the cockpit system detects that you still have power set at 20' radio altitude the call out 'retard, retard' happens.

Rudder
The rudder is the small moving section at the rear of the stabilizer that is attached to the fixed sections by hinges. Because the rudder moves, it varies the amount of force generated by the tail surface and is used to generate and control the yawing motion of the aircraft. The rudder is used to control the position of the nose of the aircraft, it is not used to turn the aircraft in flight. Aircraft turns are caused by banking the aircraft to one side using either ailerons or spoilers. The rudder is controlled with foot pedals, usually coupled to bell cranks on the rudder via wire cables.

Slats
Slats are aerodynamic surfaces on the leading edge of the wing of an airplane. When deployed, they increase lift at higher speed. So by deploying slats, an aircraft can fly slower or take off and land in a shorter distance. Slats are usually deployed with the first flap setting.

Spoilers
(ground)spoilers are flaps used to decrease the speed of the aircraft after touchdown and also ensures that the aircraft remains planted firmly on the ground.

TCAS
Traffic Alert and Collision Avoidance System, or TCAS, is an instrument integrated into other systems in an aircraft cockpit. It consists of hardware and software that together provide a set of electronic eyes so the pilot can "see" the traffic situation in the vicinity of the aircraft. Part of the TCAS capability is a display showing the pilot the relative positions and velocities of aircraft up to 40 miles away. The instrument sounds an alarm when it determines that another aircraft will pass too closely to the subject aircraft. TCAS provides a backup to the air traffic control system’s regular separation processes

Transition Altitude (TA)
A safe altitude above any obstacles within some distance of the operation area. The TA varies from country to country and sometimes even in a country. For north america, it is 18,000 feet. Above the TA, the aircraft altitude will be specified as a flight level.

Trim
Trim or pitch trim, is achieved by moving the entire horizontal stabilizer up or down. It allows a pilot to balance the lift and drag being produced by the wings and control surfaces over a wide range of load and airspeed. When a jetliner takes off, its pitch trim must be set by the pilot so that it is within the fore and aft safety limits, considering the gross weight and CG (center of gravity) of that particular airplane. The CG is determined by how much weight is in the plane, and where that weight is located.

VASI
Visual Approach Slope Indicator. A system of lights on the side of a runway that provide visual descent guidance information during the approach to a runway.

Vertical Speed
Shows ascent and descent rate indicating how fast you have gone vertically up or down.

Vertical stabilizer
A stabilizer that is part of the vertical tail structure of an airplane and supports the rudder. In some aircraft, the vertical stabilizer houses an engine, like the DC10.

VFR
Visual Flight Rules (VFR) is an aviation term referring to a mode of flight. During VFR flight, the pilot refers to things outside of the cockpit to determine position on a map - such as looking at the ground and identifying cities and mountains.

Wake turbulence
Wake turbulence is the term used to describe the effect of the rotating air masses generated behind the wingtips of an aircraft in flight. Wake vortices are formed any time an airfoil is producing lift. These vortices are two counter-rotating cylindrial air masses trailing aft from the aircraft and are particularly severe when generated by large and wide-bodied aircraft. The intensity or strength of the vortex is primarily a function of aircraft weight and configuration (flap setting etc.). The vortices are most dangerous to following aircraft during the takeoff, initial climb, final approach and landing phases of flight. Helicopters also produce wake turbulence and are significantly greater in strenght than those from a fixed wing aircraft of the same weight. Helicopters with two blade main rotor system produce stronger wake than rotor systems with more blades. Helicopters should keep well clear of light aircraft when hovering or while air-taxiing. The wake turbulence effect is not (yet) simulated in the weather engine of Flight Simulator.

Winglet
The winglet is a vertical or angled extension at the tips of each wing, altering the trailing tip vortex system from an aircraft wing and thus enhancing the aircraft performance.