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Glossary A to D

Home Up Links Glossary A to D Glossary E to P Glossary Q to Z

 

Glossary of Terminology with CRW Perspective

    If you have problems understanding CRW jumpers and their jargon, don't worry. Study the terminology below and you'll fit in before you get your first line burn. There are many CRW specific terms in the glossary below. I have also attempted to define a CRW perspective on some general skydiving terminology. If you want an explanation on materials and rigging terminology, I strongly recommend "The Parachute Manual" by Dan Poynter.

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Term Definition Country

A

AAD Automatic Activation Device. A device that measures barometric pressure and converts it into a relative height AGL and rate of descent. Once a preset altitude and rate of descent are achieved, the device activates the reserve parachute. There are also time activated AAD's & AAD's that activate the main parachute. Modern AAD's tend to be based on pyrotechnic & electronic technology. Others were based on mechanical technology.
AC Advisory Circular. A publication produced by the FAA to explain the FAR's. USA

A/C Aircraft.

Accuracy Accuracy involves landing precisely onto a predetermined landing point.
AD Airworthiness Directive. Produced by the FAA. USA
Adapter, Friction A floating friction grip adapter which allows for quick harness adjustment.
Aerodynamics The study of interaction between force, relative motion, and fluids (e.g. study of parachute flight through air).
Aft Rear of canopy (i.e. trailing edge, D, or brake lines).

AGL Above Ground Level. The altitude above the ground.
Aircraft A device that is intended for flight in air. 
Airing The act of exposing as much of the parachute material to air as possible for the purpose of drying. May be required after passing through clouds or on a rainy day.

Airspeed The speed of a flying object (canopy or aircraft) through the air. It equals the ground speed if there is no wind present or is a function of ground speed and wind. See Ground Speed. *
Air to Air Parachuting manoeuvres filmed by another parachutist who flies in the air with the performers/athletes. Used for training debriefs, judging in competitions, or vanity. See Ground to Air.
Alteration Modifications or changes to the original configuration or design of equipment from its original manufacturers specifications.

Alti Altimeter. A mechanical device that measures barometric pressure and then converts this figure into a relative altitude. The altimeter should be calibrated (set to zero at ground level) prior each jump. If calibrated, the altimeter displays the height AGL. See Relative Altitude & Altitude.

Altitude Vertical distance. Usually measured as a relative height AGL of an object in the air to the ground below. Europeans tend to use the metric system (metres) and most other nations tend to use the imperial system (feet). See Relative Altitude & Alti.
AMSL Above Mean Sea Level. The altitude above mean sea level. This figure is used by the aviation industry to assist in vertical separation of aircraft. This is due to the AGL figure changing whenever the topography (ground height) changes.
Aneroid A device that senses changes in barometric pressure. Used in many altimeters.

Angle of Attack The angle that the parachute is presented to the relative wind. This changes as the various control inputs are used. Technically it is angle between the chord line and the parachutes velocity vector.

Angle of Incidence The angle at which the canopy is trimmed to glide through the air. It is determined by the relative length of the suspension lines. If the A lines are much shorter than the D lines, then the canopy is said to have a high (steep) angle of incidence. Otherwise it has a low (shallow) angle of incidence.
APF Australian Parachute Federation Incorporated. The organisation delegated to represent the FAI in all matters relating to sport parachuting activities in Australia & its territories. It is the governing body of sport parachuting in Australia. Australia

Apparent Wind The wind as perceived by an observer.
Approved An item of equipment which has received official certification from the FAA. This approval is usually indicated by a TSO label or military designation (NAF, AAF, AN, etc). Altering the design may invalidate the approval. USA
Arch To adjust your body position such that it is more aerodynamic. This involves pushing your hips forward and forcing your arms and legs backwards. The result is an increase in descent rate.
AS-8015A Aerospace Standard 8015A. Published by the American Society of Automotive Engineers. This sets the standards which parachuting equipment must meet in order to receive approval under TSO C-23e. USA
ASI Air Speed Indicator. A device that measures and displays air speed. 
ASO Area Safety Officer. An official of the APF responsible for overseeing safety on a regional basis. See DZSO & Director Safety. Australia

Astra An AAD made by FXC Corporation from the USA.

Aspect Ratio (AR) The ratio between the span (width) and the chord (length) of a wing. Seven cell canopies tend to have a lower aspect ratio than higher performance elliptical canopies.
Assisted Deployment When someone or something else apart from the parachutist commences the deployment sequence. One technique is the PCA (pilot chute assist).
Associated Air Mass The air mass that moves with the canopy in flight. *
ATC Air Traffic Control.
AUW All Up Weight / Mass.
Auxiliary Parachute Pilot chute in the UK, and reserve parachute in most other locations.
B Back Pad Padding integrated into the harness and lies between the parachutist and harness. It provides comfort, and a sweat barrier.
Bag Lock A high speed malfunction where the canopy remains enclosed in the D-Bag during the deployment sequence.
Band, Rubber A circular piece of elastic material used to secure suspension lines in place. These are normally stowed into a tail pocket on CRW canopies.
Bartack Zigzag stitching used at high strain areas such as line attachment points.
Barrel Roll A complex, difficult, and dangerous manoeuvre where a parachutist performs a 360 degree spin/rotation in the vertical axis.

Base In CRW, the Base is usually the pilot of the formation and is the foundation and reference on which any CRW formation is built. The Base could also involve multiple jumpers, depending on the size of the formation.

Base - Pin The Base person usually exits the aircraft with or just after the Pin and they try to link together as quickly and safely as possible. The speed and smoothness of the Base - Pin has a major impact on the final result.

BASE Jumping BASE is an acronym for Building, Antenna, Span (bridge), and Earth (cliff). Base Jumping is the act of parachuting from fixed objects.
Bi - Plane A CRW formation involving two parachutists combined in a planed formation.
Blanketing A reversal of air flow & turbulence opposing the intended action of a deceleration device. *
Blow Out Blown Cell. When a cell) suffers catastrophic failure to the point where the flying characteristics are altered to the point where it may be unsafe to land the parachute. 
Board of Directors -

BOC Bottom of Container. The pilot chute is stowed in a pocket which is sewn onto the outside of the bottom flap of the main container. The BOC is the most common location for modern pilot chute stowage. See Throw Out.
Bodkin Packing tool (usually T shaped = T Bodkin) used to draw material through holes such as reserve closing loops through grommets.

Body Position A jumpers posture and position upon exiting an aircraft, in freefall, and under canopy.

Boogie A special gathering of parachutists who are usually focused on fun, specific skill development, and similar interests.
Bottom Skin Pressurisation The part of the deployment sequence where the bottom surface is fully exposed to the air flow but the cells may not have pressurised at this stage.

Bounce An incident usually resulting in injury or death. Also called: "go in", "frap in", etc.

Box-man Face to earth body position. This is a desired exit position in CRW and is where the jumper arches, forms right angles with his arms at the shoulder and elbow, legs are spread, and the knees are bent at 45 degrees.

Brake Lines / Brakes These lines are the most commonly used control inputs on a canopy for most parachutists. They are used to control speed, direction, and relative descent rate. They connect the toggles to the trailing edge of the canopy. CRW jumpers tend to use risers in conjunction with the brake lines to control the flight of a canopy. 
Breakaway See Cutaway.
Break cord Material connecting parachute components that is designed to break under certain loading criteria during the deployment sequence.
Breaking Strength The force or tension required to break a material.

Break Off When a CF reaches a certain altitude (approximately 2500 feet), or when the planned manoeuvres have been completed, the parachutists separate and fly away from each other. This is required for safety reasons.
Breathing Appears during flight as a pulsating action in a parachute and is caused by minor variations in air pressure and flow in and around the parachute.

Bridle This is either suspension line or webbing material that attaches the pilot chute to the canopy or deployment device. 
BSR's Basic Safety Requirements. The minimum requirements to ensure safe sport parachuting activities. USA - Gen
Buckle  Device used to attach two pieces of material.
Buffer Material placed between load bearing components in hardware and webbing to minimise damage to webbing.
Bumper, Slider Piece of material placed over connector links to prevent damage to suspension lines when the slider is forced onto the connector links during deployment.

Burble The area of turbulence  (low pressure / interrupted air flow) behind any object exposed to a relative air flow. This can occur in freefall and under canopy. There is a low pressure area behind a persons back when in face to earth freefall.

C

Call Indicates how long until the next aircraft sortie will depart (e.g 15 minute call).
Camera Jump Where a parachutist carries & utilises a recording device whilst in the air. Normally performed for the purposes of technical debriefing of jumps, to be able to present evidence of performance to a judging panel, to record events for posterity, etc.

Canopy Generally considered to be the material & lines of the parachute. Also a term used for the complete deployed assembly. See Parachute.
Canopy Dock See Riser Dock.
Canopy First Deployment Where the canopy is presented to airflow prior to the suspension lines.
Canopy Inflation Time The time elapsed from line stretch to full canopy pressurisation.
Canopy Release System A system where the risers are able to separate from the harness. See Cutaway & Three Ring.
Canopy Transfer Deploying the reserve canopy prior to jettisoning the main canopy. May be required on a malfunctioning main parachute at very low altitudes, where there is insufficient altitude to release the main parachute and deploy the reserve.
CAR Civil Aviation Regulation. Australia
CASA Civil Aviation Safety Authority. The organisation governing aviation safety in Australia. Australia

Cascade The point where two lines join together into one. This reduces bulk and drag.
CASI Commission d'Aéronautique Sportive Internationale.
CCR Canopy Crest Recipient. USA
CCS Canopy Crest Soloist. USA

Cell Ram air square canopies comprise of a number of pressurised cells. The suspension lines attach to the load bearing ribs on the side of each cell. Each cell is usually split into several smaller "compartments" by non - load bearing ribs. The cell is pressurised by air rapidly entering through the opening (nose) at the leading edge or by air moving sideways through the cross-ports of adjacent cells. Some canopies have mesh covered holes in the bottom skin (vents), that also allow air to flow in.

Centre The reference point or line around which movement (or manoeuvres) is related to. 
Centre Lines Suspension lines (groups A, B, C, D)  immediately adjacent to the centre point of the span of a canopy.
Centre of Gravity That point in an object where we consider the force of gravity to be concentrated.
Centre of Mass The point where we consider the total combined mass of an object or formation to be located with regards to motion. *
Certified Equipment that is TSO approved or personnel approved for particular functions &/or responsibilities by their regulating organisation. See TSO.
CF Canopy Formation. See CRW.
CFM Cubic Feet per Minute. A measure of permeability. See Permeability.
Chest Mounted Equipment or accessories attached to the front of the body. It is connected to the main lift web (usually via rings sewn into the harness), or via straps around the parachutists body. The term usually refers to a tertiary mounted parachute or a weights contained in bags (with cutaway system).
Chop Colloquial for Cutaway.
Chord The distance from the leading edge (front) of a parachute to the trailing edge (tail).
Chute Abbreviation of the term "parachute".

Closing Loop The closing pin is inserted through this loop during the latter stages of the packing process to ensure the container remains closed until deployment is commenced. It holds all the flaps of a container together & the container closed.
Closing Speed The speed at which two bodies approach each other.
Cloth Extensions Small pieces of cloth material sewn into jumpsuits whose function is to decrease fall rates and increase glide ratio. See Wingsuits.

Coach A person employed to assist a team or individual improve their performance using psychological, motivational, practical, and skill development techniques. A coach is considered compulsory for all high performance athletes. A coach usually has performed at a high level in the particular discipline and has the ability to impart knowledge to the parachutists being coached.
Compatible When two or more canopies and their pilots have similar forward speeds, descent rates, and general flying characteristics. It also refers to items of equipment that have proved via testing to function correctly when configured together. See Configuration.
Competition Where a group of individuals &/or teams compete against each other whilst following a specific set of rules or guidelines related to that activity. The activities are usually judged by an impartial & qualified judge.
Configuration A term usually related to equipment. It defines how various components of a system are connected together. It is important that equipment is compatible. Configurations should be tested &/or assessed by qualified persons.
Connector Links Provide a connection between risers and suspension lines. They are also used in other areas including some bridle attachments. The most commonly used are Rapide links. Soft links are also used.

Container The container is one component of the parachute assembly. It is permanently attached to the harness and encloses both the main and reserve parachutes in separate compartments.
Control Lines The rearmost lines on a canopy. Also called the brake lines. They are attached from the trailing edge of a canopy to the steering toggles.

Crabbing Flying at an angle to the relative wind. A technique often used when making the landing target is questionable.

Cross-ports Vents cut into the ribs of canopies to allow air flow between adjacent cells and ensure even pressurisation.
Cross Connectors These can either run from front to rear risers on either side, or across the front risers. Their main function is during plane formations to prevent a person from sliding up the lines and deforming the canopy. They can also be used on student gear 
CRW Canopy Relative Work. It is the discipline of intentionally flying open parachutes in close proximity to or in contact with other parachutes. See CF.
CRWC Canopy Relative Work Crest. An award given to a parachutist who participates in an FAI recognised, 8 way CRW formation. Australia

Currency The recency and frequency of a persons jumping activities. The less current you are, the less jumps you have made in recent times. Un-current jumpers require guidance from instructors prior to resuming normal jumping activity.

Cutaway Jettisoning a main parachute by disconnecting the main risers from the harness. It is a standard emergency procedure normally performed prior to utilising a reserve parachute. The term originated from the act of physically cutting risers or suspension lines to release a main parachute prior to the development of the Capewell & 3 Ring release systems.

Cutaway Handle Usually located on the right lift web of the harness. When pulled, you are said to be performing a cutaway.

CYPRES CYbernetic Parachute RElease System. An AAD made by Airtec GmbH of Germany. It comprises  release, control, and processing units. The processing unit is usually mounted on the bottom flap inside the reserve container. An expert CYPRES activates when the descent rate exceeds 115 fps when passing through an altitude of 750 ft. This is the most popular AAD unit in the Sport Parachuting market today.
D Dacron Common material used in the manufacture of suspension lines. Due to wear & tear and the risk of line burns, CRW canopies tend to use thicker lines than freefall canopies, especially the centre A lines, end cell A lines, and brake lines. Dacron has lower elasticity but greater durability than nylon.
Daisy Chain Method of gathering suspension line during field packing.
Damping Smoothing oscillations or existence away from an equilibrium.
D-Bag Deployment Bag. The bag in which a parachute is packed prior to packing into the container. It's functions include promoting a sequential deployment, slowing the opening (reducing opening shock), location to stow the suspension lines, and making the pack job neater. It is rarely used in CRW.

De-arch The opposite of arching. To flatten the body position & reduce descent rate but create the potential for greater instability.
Decelerate Slowing down. Usually achieved via increasing air resistance (more air molecules) or altering the flight characteristics of a body (de-arching) or parachute (flaring) whereby greater drag is induced.

Decision Altitude The altitude at which parachutists have been trained or pre-planned to begin emergency procedures. 
Demonstration Jump A parachute descent usually made away from an established DZ for the purpose of entertaining the public.
Deployment The sequence between pack opening or initiating pilot chute release, and line stretch.

Deployment System The components of a parachute system that deploy a canopy. In CRW, these components typically include a pilot chute, bridle, closing loop/pin, tail pocket, and pilot chute retraction system.
Deployment Device A D-Bag, sleeve, diaper, pilot chute, or other device used to initiate deployment and/or promote a sequential deployment of a parachute and to reduce opening shock.
Deployment Method The technique used to initiate the deployment sequence. These include pilot chute assist, static line, hand deployed, ripcord, D-Bag, etc,
Diamant A CRW specific canopy made by The Parachute Shop, Bensancon, France. It was designed for use as a sequential canopy. *
Diaper A deployment device attached to the bottom of a round canopy or the top of a ram air canopy. It prevents canopy inflation until line stretch and keeps the canopy shape intact until then.
Director of Safety A highly experienced elected official responsible for overseeing all matters related to parachuting safety in Australia. See ASO & DZSO. Australia
Direct Supervision Where skydiving activity is supervised by a qualified person who is physically present at the time.

Dirt Dive Rehearsing a parachute jump. There are many techniques including practically running through the jump on the ground, mental visualisation, modified practical / mental rehearsal in the plane.
Dock Where one parachutist positions their parachute to link with another parachutist.
Dock - Plane See Plane.
Dock - Stack See Stack.
Dock - Stairstep See Stairstep
Dock - Wing See Wing Dock.
Donut or Shutdown Sunday Inducing a severe rear riser stall on some canopies (e.g. PD Lightning with rotations trim and several hundred jumps) will cause the leading edge of opposite end cells to touch each other whilst the centre is clear. 

Down Plane Two or more linked parachutists flying straight towards the ground (leading edge pointing to ground). They are usually linked at the body and their canopies are separated. 
Down the Back Traditional Rotations technique involved the pilot stalling his canopy over the back of the formation and then intentionally using the burble to fall faster to the bottom slot. There were two negatives, flying an inefficient wing in turbulent air meant losing some control, and you had to cover more distance getting over the second canopy. See Sashay.
Drag One of three main forces acting on an non-powered wing. It inhibits canopy performance (glide, descent rate, etc) by subtracting from beneficial lift and weight forces. See Lift & Weight.
Drag Plane Three or more parachutists build a plane and the bottom parachutist(s) fly their canopies "upside down".
Drift The wind induced component of horizontal displacement of a parachutist over ground during descent. Usually checked using a WDI or by visual references.
D-Ring A metal fitting usually sewn into the main lift webs. Often used to connect tertiary parachutes and weight & flag bags via snap on connectors.
Drop the Bomb A quad is built. The two middle parachutists hold together whilst the pilot locks his feet into the 2nd persons risers. The 2nd person cuts away and the pilot flies off with the ghost plane. The 3rd and 4th persons create a down plane whilst the second still holds on. When the down plane is broken off, the second person drops away and then deploys the reserve.

Dytter An audible warning device made by Larsen & Brusgaard of Denmark.
Dual Assembly A parachute system containing a harness/container, main and reserve parachute, and associated deployment systems.

DZ Drop Zone. A specified area where parachutists are permitted and plan to land. This is usually at a registered skydiving centre or in other varying locations for display jumps.
DZSO Drop Zone Safety Officer. The person responsible for overall safety at a particular drop zone during parachuting operations. See ASO & Director Safety. Australia

    This list is derived from Tom Begic with reference to the APF, USPA, BPA, The Skydivers Handbook, The Parachute Manual, and various internet sites.

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Copyright © 2005 OzCRW. Last modified: May 16, 2005