Acro – Aerobatic paragliding

Adiabatic – Referring to a change in an airmass in which no heat transfer is involved. Typically, the temperature changes as density changes (lapse rates).

ADS-B – (Automatic Dependent Surveillance Broadcast) A type of transponder combined with a GPS to allow accurate electronic conspicuity.

Aerofoil – The curved shape that offers a favourable lift/drag performance when used in an aircraft wing or surface.

AGC training, Advanced Glider Control – These are further training courses designed to help pilots explore the limits of their gliders’ capabilities and deal with departures from normal flight. Conducted at height and over water with a rescue boat available if required for added safety.

AGL – Above ground level

Airbag – A valved space used in paragliding harnesses to increase the deceleration distance,and offer protection to the pilots spine in the event of an impact.

Airspace classification – The structure of controlled airspace classifies each piece into a class, each with its own rules for aircraft using it.

Airspeed – The speed of the airflow over the wing (from front to back)

Air Traffic Control (ATC) – Ground-based service where the controllers advise and direct aircraft they are in contact with, always by radio and often by Radar/ transponder tracking.

Air traffic Zone (ATZ) – The zone of restricted airspace immediately surrounding an aerodrome, which can only be penetrated with the appropriate permission (usually from ATC).

Airway – Corridor of controlled airspace used by commercial air traffic. In most cases VFR flying is not permitted.

All Up Weight  – The total weight of the aircraft and payload that leaves the ground. (I.e. including passenger, fuel etc).

Altimeter – Instrument that displays altitude information to the pilot relative to a pre-set datum.

Alto- (Cloud name) – Prefix that classifies the cloud as being between 8,000ft and 18,000ft AMSL.

Anabatic – An upslope airflow generated by convection activity.

Angle of attack – The angle between the chord line of a wing and the relative airflow.

Angle of incidence – On fixed wing aircraft the angle between the chord line of the wing and the longitudinal axis of the fuselage. As paragliders do not have a fuselage the AoI is usually taken to refer to the angle between the pilot’s position (relative to horizon) and the wing.

APPI – Association of Paragliding Pilots and Instructors.  Founded in 2009 by David Arrufat, a Swiss pilot, the APPI is an association which has a syllabus and rating system that is sometimes used by pilots and instructors in countries without a national governing body.

Aspect ratio  – An expression of the shape of an object.  There are slightly different methods of calculating this figure. In paragliding the formula often used is calculated by dividing the square of the span by the area of fabric. For example, a canopy with a span of 10.5 metres and an area of 25 square metres would work out as 10.5 x 10.5 = 110.25 divided by 25 = an aspect ratio of 4.41.

Autorotation – A paraglider is usually stable in roll, due to pendular stability, but in a high G turn and/or when it is partially collapsed, the forces can act in such a way that the glider remains in a stable spiral.  This is an autorotation.

Backing – An anti-clockwise change in the wind direction, E.g. from Northerly to North-Westerly.

Base leg – The penultimate portion of an aerodrome circuit pattern, This is the crosswind element, after the Downwind leg but before Finals.

Bearing – Course following a compass heading.

Bernoulli – In 1738 Daniel Bernoulli published his principle regarding the relationship between the speed and the static pressure of a gas or liquid. This is one of the basic principles on which aerodynamics relies.

BHPA – British Hang Gliding and Paragliding Association.  The governing body of the sport in the UK.

Big ears – A deliberately induced collapse of the outer cells on each wing tip to reduce the wing area and increase the sink rate of a paraglider.

B-line stall – A deliberately induced distortion of the aerofoil section of a  paraglider. This disrupts laminar flow, reduces airspeed and causes a very rapid descent.

Brummel hook – Small steel or aluminium component for quick connection or disconnection of two lines or cords.  Frequently used on speed systems.

Cascade – Either: The splitting of a line into several branching lines: e.g a control line cascade. OR, a term used if one instability situation evolves (quickly) into two or more instability issues.  E.g., a stall results in a forward pitch that results in a collapse that results in an autorotation.

Chord – A straight line from the trailing edge to the leading edge of a wing, used as a datum for angle of attack.

Cirro- (Cloud name) – Prefix that classifies a cloud as being above 18,000ft AMSL.

Cirrus (Cloud name) – Wispy high level clouds, often composed of ice crystals, which may be the first sign of an approaching warm front.

CIVL – (Commission International Vol Libre). The FAI’s Hang gliding & Paragliding commission. CIVL administers record claims, competitions, sporting codes etc.

Club Pilot – BHPA rating; CP is the point at which new pilots no longer have to be supervised by an instructor.

Cobra launch – A technique useful in stronger winds or restricted launch areas.

Cold front – The zone where a moving cooler airmass is in contact  and interacting with a warmer airmass.

Concertina packing – Technique that minimises stress to leading edge stiffening materials.

Conduction – Heat transfer mechanism, Where a warmer surface transfers heat to a cooler medium that is contact with it. Typically from the surface to the airmass lying on it.

Constant aspect approach – Landing approach technique, a modified version of the powered aircraft circuit approach that is used by unpowered craft.

Control Area (CTA) – Controlled airspace. These usually overlay CTR’s above an aerodrome; and extend from one altitude to another altitude or flight level. Usually Class D but can be Class A.

Convection – The process of warmer and less dense air rising.

Control Zone (CTR) – Controlled airspace around aerodromes, they extend from the surface to around 2,000ft or higher. Usually Class D.

Convergence – In terms of weather, when two airmasses moving in different directions meet, typically above mountain spines or along sea-breeze fronts.

Converging course – In terms of aircraft movement: converging is when two aircraft are on courses that will result in a collision if one or both do not change course or altitude.

Core – The part of a thermal that is ascending fastest.  To core: (v) to fly a flight path that most effectively remains in the area of the strongest lift.

Coriolis effect – The pattern of deflection taken by objects or airmasses as they travel long distances above the surface; caused by the rotation of the earth, which is at different speeds depending on latitude.

Crabbing – A flight path where the aircraft is pointing in a slightly different direction to the direction of travel over the ground, due to a cross-wind.

Cravat – Term used to describe the situation where a piece of the canopy fabric becomes trapped in the lines.

Cross-country – Flight away from the take-off site, using any lift sources en-route to maintain altitude and cover distance.

Cumulonimbus – (Cb) Cloud type, literally, a cumulus cloud bearing precipitation. Is used to describe a cloud with massive vertical development that is associated with thunder and lightning, hail, torrential rain, gust fronts and severe turbulence. 

Cumulus Cloud type – A heaped cloud generated by convection activity, which occurs when a thermal reaches dewpoint.

Danger Area – A hazard to aircraft marked on aeronautical charts, usually military firing ranges.

Deep Stall – An instability situation where the glider is no longer generating lift and is descending very rapidly, but the wing is not collapsed.

Dew point – The temperature at which the air reaches saturation point, and water vapour condenses into visible water droplets. Cloudbase occurs at dewpoint.

DGAC – French system for recording paramotor wing recommended load information (As declared by the manufacturer).

DHV – Deutscher hangelieterverband. German governing body of the sport. The DHV also manage and award airworthiness certification (the LTF system).

Downwind – In the direction the wind is travelling.

Drag coefficient (Cd) – A number used by aerodynamicists to describe the effect of different shapes on the drag generated by airflow around an object.

Dry adiabatic lapse rate (DALR) – The rate at which dry air cools with altitude. 30C per 1,000ft

Dyneema – Material used for paraglider control lines or short (upper) suspension lines

Elementary Pilot’s Certificate (EPC) – BHPA rating level. Typically achieved after about 4-6 days training for a new student.

EN – (European Norm) Product Certification standards body.

EN 966 – Airsports helmet certification standard.

EN 1077 (A & B) – Snowsports helmet certification standards. (A is acceptable for airsports, B is not).

EN 926-2 – Paraglider flight safety certification standard (flight tests).

EN 926-1 – Paraglider load test standard.

EN 1249 1 – Emergency parachute certification standard.

Environmental Lapse Rate (ELR) – The rate at which the atmosphere cools with height. This is a variable value and depends on several environmental factors.

Final approach (Finals) – Last leg of a landing approach.  Wings are level and the aircraft is being slowed immediately prior to touchdown. 

FLARM – Flight Alarm, an electronic conspicuity system. FLARM is widely used by sailplane pilots.

Flight Level (FL) – The readout of vertical position when the altimeter is set to the pressure setting for the ICAO standard atmosphere.  (1013.2hPa @ 150C at sea level).

Flight Radio Telephony Operators Licence  (FRTOL) – CAA licence required to operate an airband radio.

Foehn – A dry warm downslope wind that occurs in the lee of mountainous areas. Poor flying conditions.

Full stall (Dynamic stall) – In paragliding: when the canopy has been stalled and then collapsed as a result of lost internal air pressure.

Geostrophic Wind – The wind direction at 2,000ft above the surface. At this height the wind is not affected by the Coriolis affect which deflects the flow direction of surface winds.

G-Force – The load experienced by the pilot and glider, in level flight it is 1G, under tow it can be 2G in a high-speed spiral it can exceed 6G.

Glide angle – Ratio of height lost to distance covered over the ground e.g a 1,000m flight from 100m height is a glide angle of 10:1 .

Global Positioning System (GPS) – Instrument that determines location by reference to a number of satellites.

Groundspeed – Speed of the aircraft  over the ground.

Heading – Direction in which the aircraft is pointing (often determined by a compass reading).

Hook knife  – Knife with an enclosed blade that can be used to cut line or webbing (but not to stab yourself).

Humidity – The percentage of water vapour in the air relative to the saturation limit. 

Hypothermia – Adverse reaction to prolonged low temperatures. Where the body’s core temperature is under threat and the body closes down functions.

Hypoxia – Adverse reaction to a reduced oxygen supply, usually caused by high altitude where pressure is reduced to the point that the body cannot process sufficient oxygen.

Instrument Flying Rules (IFR) – Regulations governing flight when in IMC (instrument flying conditions) e.g poor visibility.

Instrument Meteorological Conditions (IMC) – Flying conditions which fall below VMC minima. (poor visibility).

International Civil Aviation Organisation (ICAO) – United Nations air navigation body set up to promote international co-operation on air transport and related issues.

Inversion A situation where the air temperature increases with altitude, often encountered in regions of high atmospheric pressure.

IPPI – The CIVL pilot rating structure.

Isobars – The lines drawn on a surface pressure chart to link points ore equal pressure. Usually shown with 4hPa spacing.

Katabatic winds – Downslope winds commonly encountered in mountainous areas early and later in the day when there is insufficient heat to generate an anabatic flow.

Kevlar – Trade name for super-aramid material. This is the usual material chosen for paragliders suspension lines as it is very strong and resistant to stretch or shrinkage.

Lapse rate – The rate at which temperature changes with height.

Lift/Drag ratio (L/D) – The resultant is the effective force acting perpendicular to the weight (usually vertically up). It is composed of both drag and lift, and the ratio of the two forces is expressed as an L/D ratio. The greater the lift in relation to the drag, the flatter the resulting glide path of the aircraft will be.

Leeside – The downwind side of an obstacle, usually a mountain or ridge.

Lee wave – Wave lift often has its peak some way downwind of the feature that triggered it, this why it is sometimes referred to as “lee wave”.

Lenticular – Type of cloud caused by wave, easily identified by its smooth shape (often lens shaped), cross-wind orientation and lack of movement.

Line-over – The situation where a poorly laid-out paraglider has a line over the top of the canopy fabric.

Live tracking – Used by some competition pilots and expedition pilots, live trackers, transmitting GPS data, allow the pilot’s position and speed to be viewed on the internet.  This can be a useful safety tool and add a great element of interest to competitions.

Lock-out – The situation during a tow launch where the glider drifts off-line to the point where the line tension is acting to pull them into the turn and the ground.

LTF – Certification system administered by the DHV.

Military Aerodrome Traffic Zone (MATZ) – An additional outer “shell” of space beyond a military aerodrome ATZ that may contain a high concentration of air traffic, possibly fast moving. Marked on aircharts to warn other air users. Not illegal to penetrate without prior permission but not advisable under most circumstances.

METAR – A report of the actual real-time weather conditions at an aerodrome; accessed through the Met Office AirMet Website.

Nimbo- (Cloud name) – Rain (or snow) bearing cloud.

Nose down spiral – An established spiral dive where the glider has accelerated to the point that the leading edge is pointing at the ground.  This results in dramatic height loss and high G forces.

Occluded front – The situation where a faster moving cold front has caught up with a warm front and undercut it, pushing the warm airmass clear of the surface.

Parachutal stall – See Deepstall.

Parachute landing fall – Technique to minimise injury in the event of a fast/steep approach and impact, the PLF relies on increasing the deceleration distance and rolling on the hips and back to reduce point stress on the limbs.  

Pitch – Rotation around a lateral axis, i.e nose up or down.

Polar Curve – Graph plotting the sink rate performance of a glider against its airspeed.

Porosity – The measure of how much air can “bleed” through fabric.  High porosity is a good indicator of ageing fabric and is used as a key indicator during annual airworthiness checks.

Pressure altitude – Altimeter reading based on a datum of the ICAO standard atmosphere, i.e a flight level.

Prohibited airspace – Aircraft may not penetrate these areas.

Pulled-down Apex – Classic design of emergency parachute which maximises the Cd of a round parachute.

QFE – Altimeter reading when above a specific datum point such as airfield or take off point.

QNH – Altimeter reading when set with sea level as the datum point (Zero).

QNE – Altimeter reading when se at “normal” datum, which is the ICAO standard atmosphere. (1013.2hPa @ 150C at sea level).

Radiation – Mechanism of heat transfer, this is via sunlight passing through the atmosphere and heating the ground.

Reflex – Type of canopy design which reduces the tendency of a wing to pitch forwards (and therefore risk collapse) when flown at a low angle of attack. This has some negative side effects on handling characteristics but is particularly useful to pilots flying under power.

Ridge lift – The pressure wave of air forced up over a hill or ridge when the wind blows towards it.  As long as the glider stays within the region with an adequate vertical component to the airflow, altitude can be gained or maintained.

Rogallo – Named after its inventor Dr Francis Rogallo, this is the design of steerable parachute that was investigated by NASA as a space craft recovery method, taken up by enthusiasts home-building the very earliest hang gliders, and is now utilised as a very effective emergency parachute system.

Roll – Rotation about a fore and aft axis (wing up or down, banking).

Saturated – Air that can hold no more water vapour at that temperature.

Saturated Adiabatic Lapse Rate (SALR) – The rate at which saturated air changes temperature with height (typically 1.5C0 per 1,000ft).

Sea breeze – The phenomenon of an onshore breeze, generated by the cooler denser air over the sea flowing in to displace warmer less dense air over the land.  Often a daily phenomenon in regions with high daytime temperatures and cool seas or oceans nearby. (At night as the land cools, especially if mountainous, the opposite, a land breeze can occur).

SERA  – Standardised European Rules of the Air.

Sharknose – A design feature originated by Ozone Gliders that allows a wider range of angles of attack to be effective in pressurising the aerofoil.  This adds a degree of stability, especially at higher airspeeds.

Sink Rate – The rate at which a glider descends through the airmass.

SIV training  – Simulation d’Incident en Vol See AGC.

Skin Friction – A component of profile drag, the drag created by an uneven airflow over the tiny variations in a surface that is not perfectly smooth.

Skywings – Magazine of the BHPA published monthly and distributed to all BHPA members.

Slope landing – Often called side slope landing, this is the technique of landing cross-wind on sloping ground.

Soft links – Lightweight alternative to steel or aluminium carabiners. Softlinks are typically Kevlar cords with a self-locking system.

Span – The dimension of a wing measured wing tip to wing-tip, the projected span is the measurement in a straight line when the glider is inflated and in the flying configuration.

Speed riding – The term for flying a very small and highly loaded paraglider wing, often in close proximity to the terrain and usually when taking off and landing using skis.

Spin – The situation where one side of the wing stalls while the other is still flying resulting in a rotation about the vertical axis.

Spiral Dive  – A steeply banked continuous turn, the flight path resembling a drill bit. A very effective way to shed unwanted altitude, but requires good skills to manage safely.

Spreaders – System to share the load of two pilots flying on one glider. Dual pilots use either soft or rigid types depending on the situation.

Stabilo line – The outermost suspension line that connects to the wing-tip of the glider.

Stall – A break up of the smooth flow of air over an aerofoil, caused by an angle of attack that is too great for the air to remain laminar over the top surface of the wing.

Static front – A weather front that remains stationary.

Stratus (Cloud name) – A layer cloud, usually featureless.

Strato- (Cloud name) – Prefix for any type of cloud that is arranged in layers E.g Strato-cumulus.

Surface pressure chart – A weather forecast chart based on the expected pressure distribution pattern. Pressure areas are mapped with isobars and the charts also indicate fronts.

TAFF – A Terminal Aerodrome weather forecast, giving a very accurate forecast including winds at altitude and cloud types and cover for the area around an aerodrome. Available through the Met office Airmet site.  Like METARS these forecasts use many abbreviations and codes and require some knowledge or a key to decode.

Terminal manoeuvring area (TMA) – An area of controlled airspace around a large airport where there is a high volume of traffic.  Generally Class A.  (Terminal Control area in the USA).

Thermal – An area, bubble or column of air that is warmer than the surrounding atmosphere and therefore rises, and is a useful source of lift for pilots.  Thermals often reach dewpoint, the temperature where the moisture condenses into visible cloud, the warm air continues to rise (although a slower rate) within the cloud and this give the cloud a vertical dimension. These heaped clouds are cumulus.

Tip-steering – A method of altering course that is favoured by power pilots or competition pilots when flying for extended periods at high speed.  Not very effective in comparison to the primary controls but efficient as it adds very little drag.

Top landing – The technique of landing back on the top of a flying site close to the launch point.

Tow Coach – An experienced BHPA pilot who is qualified to supervise a towing operation.

Towing – Launching using a winch or vehicle tow to gain altitude before releasing to fly down or search for lift. Favoured by pilots who live well away from any suitable mountain sites and schools who can use one field for many wind directions. 

Tow release – Line connection mechanism at the pilot’s end that they can activate when they wish to disconnect from the tow line.

Tow Operator – Person (licenced by the BHPA in the UK) to operate a winch or vehicle tow system.

Transition Altitude – The altitude at which controlled airspace has a vertical dimension given as a flight level rather than AMSL or AGL. This is where a pilot should re-set or switch the altimeter QNE to show position as a flight level in order to avoid infringing controlled airspace. Usually 3,000ft AMSL in the UK.

Transponder – A transmitter-responder instrument that allows ATC to identify and track you. Some airspace is a TMZ (Transponder Mandatory Zone). You must also have a suitable radio as ATC may require you to set a SQUAWK code on your transponder.

Trimmers – These are devices built into the riser set on some paragliders that allow the pilot to alter and set the angle of incidence in flight.  Normal on Dual paragliders (where a foot operated accelerator is impractical) and on power-specific wings, where the thrust can change the angle of incidence (and therefore the angle of attack) significantly. Trimmers allow the pilot to re-set a more appropriate angle.

Twist-lock Karabiners – A type of karabiner that used a spring-loaded half twist of the shroud over the gate to lock the karabiner closed as soon as the pilot lets go of it, minimising the risk of flying with the gate open.

Two-metre radios – VHF transceiver type commonly used by free-flight pilots.

Uncontrolled airspace – In the UK this is designated Class G airspace. Despite the name, even within Class G there are areas where flying is restricted or prohibited.

Unstable air – Air where there is convection activity present.  This means there may be useful thermal lift, but it also means there may be turbulence.

UV light – Ultra-violet light is a component of sunlight which is damaging to the fabrics and line materials used in paragliders. Exposure to prolonged intense UV ages and weakens paragliders and is best avoided if possible.

Valley winds – In mountainous areas the anabatic and katabatic flows often generate up-valley winds on active days that can mean valley landings are windier than at height. These winds may switch direction in late afternoon.  They may also make landing in narrow valleys hazardous.

Variometer – Instrument that indicates the rate of descent or ascent.

Veering – A clockwise change in wind direction, e.g from South to South-Westerly

Venturi effect – This is phenomenon of a gas or liquid accelerating if it is constricted, e.g by flowing in a narrowing valley or over a ridge crest.

VFR (Visual flight Rules) – All paragliding flight is under VFR. If conditions deteriorate to the point where you cannot maintain VMC you must land.

VMC (Visual meteorological Conditions) – The visibility criteria for VFR flight.

Warm Front – The situation where a warm airmass is moving and encounters a cooler airmass, it slides up over the cooler denser air and the interface is a warm front. This can affect a very large area.

Water vapour – Water in its gaseous form.

Waypoints – Pre-determined points on a flight plan. Commonly used as turnpoints in competitions.

Wind gradient – The change of windspeed with height. On flat ground, the surface winds are generally lower than those at height due to the friction of the airmass flowing over the terrain.

Wing-loading  – A 100kg all-up weight flying a glider with an area of 25kg would have a wing loading of 4kg per m2  – This figure gives us useful information about the likely behaviour of the glider. Higher wing loading will be more dynamic interactions, be better able to manage turbulence but have a poorer sink rate.

XC – Abbreviation for cross-country (flight)

Yaw – A rotation about a vertical axis, e.g a flat spin.