to READ THE FIRST FEW PAGES

BIRDBRAIN PUBLISHING LLC
F o r U p To D a t e I n f o r m a t i o n a n d E x t r a M a t e r i a l , G o To w w w. b a s e - b o o k . c o m
Contents
BirdBrain Publishing
Planet EARTH
www.base-book.com
Copyright 2010 by BirdBrain Publishing
All rights reserved.
No part of this book may be reproduced in any form, or by any
electronic mechanical or other means, without the permission in
writing from the publisher.
Written by Matt Gerdes
Edited by Mary Catherine O’Connor
Layout by Matt Gerdes & Loren Cox
All Graphics and Illustrations by Loren Cox
Cover Photo: Dean Potter meditating on ‘The Ecstasy Board,’ the largest
BASE jump in the world at the time of printing, and an exit he opened
in August of 2009, together with Andy West. Photo by Corey Rich
Inside Cover Page: Mattt G above the Gorges du Verdon, France. Photo
by Dom Daher.
Gerdes, Matt
The Great Book of BASE: BirdBrain
ISBN 9780984555611
Disclaimer................................................6
Forward....................................................8
Introduction..........................................12
1 Before You Begin...............................16
2 Begin With the End in Mind............22
3 Pre-BASE Training.............................26
4 Objects................................................40
KL Tower................................................56
Castelton Tower.....................................58
5 BASE Gear...........................................62
Bridge Day..............................................76
Lauterbrunnen.......................................78
6 Deployment Process...........................82
7 Choosing Partners..............................88
8 Ethics...................................................94
9 Packing to PLF..................................102
10 Jumping Progression......................116
Moab.....................................................136
Norway..................................................141
11 Weather............................................144
12 History.............................................164
13 Technical Info..................................178
A Short Career......................................189
A Line for the People...........................192
14 The Whole Earth.............................195
15 Sub-section, Static Lining...............200
16 Whole Earth (Continued)..............205
17 Advanced Tech. (wingsuit).............216
18 Tracking & More.............................228
19 Staying Alive....................................244
Appendix...............................................253
Thanks...................................................266
Index......................................................267
Photo by Ricardo Valbuena. Edited by Jhonathan Florez
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T H E G R E AT B O O K O F B A S E
T H E G R E AT B O O K O F B A S E
Warning!
No reason to sue, it’s your fault
Warning!
No reason to sue, it’s your fault
The Great Book of BASE is NOT an instruction manual. You cannot learn to BASE
jump by reading this book. The content here is offered for entertainment purposes
ONLY.
THE INFORMATION HEREIN IS PRESENTED “AS IS” WITH NO EXPRESS OR
IMPLIED WARRANTIES WITH REGARD TO ANY INFORMATION PROVIDED
and THE AUTHOR AND PUBLISHER SHALL NOT BE LIABLE FOR ANY
INJURY, COST, OR DAMAGE ARISING EITHER DIRECTLY OR INDIRECTLY
FROM YOUR ACTIONS. IT IS SOLELY YOUR RESPONSIBILITY TO EVALUATE
THE ACCURACY, COMPLETENESS AND USEFULNESS OF ALL OPINIONS
PROVIDED HERE.
YOU and ONLY YOU are responsible for your actions and for your life. By reading this
book, or even opening or barely touching it, you agree to take FULL RESPONSIBILITY
for your actions in life.
IN NO EVENT WILL THE AUTHOR OR PUBLISHER BE LIABLE FOR ANY
INCIDENTAL, CONSEQUENTIAL, OR INDIRECT DAMAGES TO YOU OR ANY
PROPERTY.
If you BASE jump, or even attempt anything like BASE jumping, YOU COULD DIE.
This book discusses an activity THAT CAN KILL YOU.
By reading this book, you agree to indemnify, defend and hold harmless the author
and publisher and all related employees, agents, and suppliers against all losses,
expenses, damages and costs, including reasonable attorneys’ fees, resulting from any
violation of this Agreement (including negligent or wrongful conduct) by you or any
other person who reads this book.
READ THIS!!! WARNING: this book discusses a dangerous and lethal activity!
BASE jumping is extremely dangerous. It is so dangerous that we seriously encourage
you to not do it. In fact, we honestly think it’s a bad idea.
NO WARRANTY IS OFFERED AS TO THE COMPLETENESS OR ACCURACY OF
THE MATERIAL IN THIS BOOK.
BY READING THIS BOOK, YOU AGREE TO BE BOUND BY THE TERMS AND
CONDITIONS SET FORTH BELOW. IF YOU DO NOT WISH TO BE AND AGREE
TO BE BOUND BY THESE TERMS AND CONDITIONS, YOU MAY NOT READ
THIS BOOK.
This book is the sole opinion of the author. The information herein is not intended as
advice and should not be used to replace any training.
This book was written merely to entertain the reader. If you do anything recommended
and/or suggested in this book, you do so at your own risk.
The information in this book cannot replace proper training!!!
This book is solely intended to be the author’s opinion for reader entertainment and
is not professional advice. The information provided is intended to entertain readers
only.
The author, publisher, and any employees, agents, suppliers, and any third party
information providers expressly disclaim any responsibility for any damages, injury, or
fatality occurring as a result of use of the opinions included in this book.
By reading the information contained in this book, you agree that you understand that
the content provided is for entertainment purposes only.
Neither the publisher nor the author shall be liable for injuries, deaths, or damages
arising from your participation in the sport of BASE jumping or anything related to
the sport of BASE jumping.
There may be errors in this book resulting from the mistake of the author and/or
the people with whom he consulted. The information was gathered from a variety of
sources, which may not have been independently verified. Those who provided the
information may have made mistakes. The author may have made mistakes in the
conveyance of the information in this book. The author cannot, therefore, guarantee
the correctness of any of the information contained in this book. You must keep
in mind that the information in this book may be erroneous, so use your own best
judgment.
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T H E G R E AT B O O K O F B A S E
T H E G R E AT B O O K O F B A S E
The author, editors, and publishers advise readers to take full responsibility for their
safety and know their own limits. The publisher and the author make no representations
or warranties with respect to the accuracy or completeness of the contents of this work
and specifically disclaim all warranties, without limitation.
FORWARD
FORWARD
Forward
By Harry Parker
The book you are holding in your hands represents the most comprehensive look at BASE
jumping to date. BASE jumping is an underground sport and is highly susceptible to passionate,
highly varying interpretation by the jumping community. Finding common ground is rare and
everyone has an opinion. With the recent decade of explosive growth in this otherwise nonmainstream sport, this book is long overdue.
Back in the 90s, it was hard to get anyone to agree. The Cliff Jumpers Association of America
(CJAA), founded by Dennis McGlynn, represented the second generation of jumpers attempting
to find some common ground in practice, theory and thought. The heart of the effort was to
forge unity in hopes of getting access to sites, especially to our National Park System, without
having to run from the cops.
In 1997, the CJAA published “The CJAA Guidelines” providing the first real look at acceptable
BASE standards and practices, through the eyes of the most highly respected manufacturers of
the time. This publication was written for our survival.
During that time, real unity occurred. Legal events began to emerge, concentrating on
competition through the International Pro BASE Circuit (IPBC). Through these events,
a generation of BASE jumpers was trained in packing, exit, and landing technique. The
events opened up many sites which are taken for granted today. Mentors became full-fledged
instructors with evolving courses, manufacturers took a quantum leap in their business
practices, and equipment reached safety levels never before thought possible.
More than ten years ago I tried to visualize what the sport would be like as jumpers would come
from other disciplines, such as climbing and hang gliding, and from the other outdoor sport
communities. In order for access to actually happen, our activity needed to cross the cultural
lines of sport. And it has.
During my time fighting for access I saw an obvious culture inevitability: We were backcountry
parachutists learning to navigate a world that was completely foreign to the DZ we came from.
We were placing ourselves in the open and possibly dangerous wilderness. It was dangerous
because we were not trained, and we were the foreigners. Hiking six hours into the backcountry
can get you in a lot of trouble and change your life forever if someone breaks a femur and you
don’t know what to do. Weather changes in an instant and can make an exit next to impossible.
When you add BASE jumping variables to backcountry risks, you create a potent statistic
cocktail.
Matt Gerdes is a professional paraglider pilot who has been involved with the paraglider testing
and design industry for a decade. He has racked up more than 2,000 hours of flight time at sites
all around the globe, with a perfect safety record. Matt has made over 550 BASE jumps (at the
time of printing), and his experience as a paragliding instructor for more than 10 years gives
him the perspective needed to compile a book of information such as this. Matt’s complete
immersion in outdoor sports also includes big wall climbing and backcountry skiing with many
years of experiences, both good and bad, in the open wilderness. His combination of mountain
sports and the years spent doing them has created an excellent lens through which to view our
sport of BASE jumping.
Just reading the weather portion of this book is worth the cover price. As many BASE jumpers
leave the states and flock to the big mountains of Europe and beyond, many of us go unequipped
to meet our real nemesis, the land and earth itself. Just ask anyone who has spent an evening,
unprepared, on the top of a Norwegian wall.
Nothing is perfect, and no book can encompass every detail of any one subject, nor every
viewpoint. Every book is subject to the eyes that wrote it. What you are holding in your hands
is one of only a few published works on the guts of BASE. It includes theory and discusses
standards of acceptable practice for the sport you love. Many have given their lives to learn
some of these valuable lessons and much of the info in this book is probably already out there
somewhere. What makes this book invaluable is the comprehensive nature of the information
and having it all in one reference -- written specifically for BASE jumpers by a BASE jumper.
As BASE jumping moves into the next decade and our sport opens more possibilities for
practice, some hope that we, as a group, further cross-train and educate ourselves. Being safe,
respectable and professional isn’t just about being able to exit stable anymore.
After sampling this book I can’t help but wonder what the next ten years will bring to the sport
of BASE jumping. What I do know is that the sport is always in need of comprehensive and
accessible information, like this book. People like Matt should be supported in their efforts to
bring out the best in ourselves and our sport. I’ve stood on the edge with Matt a couple of times.
He is focused, motivated and an experienced jumper; but above all, he is humble.
Buy this book; read it, practice it, share it.
-H.P.
Harry Parker’s skydiving career spans more than 20 years and his BASE jumping career almost as long. While attending the University
of Florida, Harry was president of the University of Florida Falling Gators, and took the team to its first Collegiate competition in 1989.
He also created a demo team that served the surrounding area. After college, Harry traveled the US as a rigger and videographer
for skydiving events, concentrating on the boogie circuit, which
brought him to live in California after more than five complete cross
country trips. During that time Harry grew into BASE jumping and was
fortunate to experience some of the most pristine natural jumping
sites that the US has to offer.
In 1994, Harry became one of the founders and president of the Cliff
Jumpers Association of America. The CJAA organization was dedicated
to unifying, standardizing and creating access for BASE jumpers in the
United States. This organization and its members created some of the
first real organized, open and legal BASE jumping events since the
inception of Bridge Day. Shortly afterward, he partnered with Dennis
McGlynn and Avery Badenhop and the three formed the International
Pro BASE Circuit. The IPBC was dedicated to many facets of BASE
jumping: raising experience and proficiency levels, standardizing
equipment and theory, and increasing site knowledge and site access
through competitive BASE jumping in the US. Above all, the IPBC
was committed to pushing the edge in all directions of what could
and, as others sometimes said, couldn’t be done. By the time the
late 90s rolled around, the IPBC was running Bridge Day and holding
international BASE demonstration events throughout Asia, attracting
hundreds of BASE jumpers, both new and seasoned.
Throughout the years, Harry has concentrated more and more on his
skydiving photography and video. You can still find Harry at Bridge
Day, announcing all the thrills, chills and spills of the event.
Harry Wingsuiting Kjerag, 2003
www.TheHarryParker.com
Photo by David Major
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T H E G R E AT B O O K O F B A S E
T H E G R E AT B O O K O F B A S E
THE DEPLOYMENT PROCESS
CHAPTER 6
The Deployment Process
Links in a Chain
Understanding the chain or sequences that lead to a successful canopy deployment is
important and relatively simple. There are many malfunctions possible in the sequence,
any one of which can kill you if allowed to happen. From your pilot chute to your leg
straps, your equipment forms a chain in which every link is vital to your survival. Treat
your equipment, the sport, and your progression as if your life depends on the perfect
deployment of your parachute and the flawless piloting of your canopy.
The Pilot Chute
It goes without saying that although you must deploy your pilot chute (PC) in a clean
and balanced manner, you must also throw it as though your life depends on it,
because it does. A weak pilot chute toss can lead to a pilot chute hesitation, in which
the PC struggles to inflate in the turbulence behind the jumper (the burble). It can
also encourage bridle-PC or bridle-jumper entanglements, particularly if during an
unstable or aerobatic deployment. Once you deploy your pilot chute into clean air and
it inflates fully, extends your bridle, and begins to open your container, the deployment
process has begun.
Photo and sequence by Bryan Rapoza
Find Balance...
Don’t overthrow! Certainly, throw your PC as if your life depends on it, but overthrowing may cause your
PC to oscillate, rotate, and lead to asymmetric canopy extractions and off heading openings. Not to
mention the fact that it will probably ruin your body position.
also increase the amount of time that the packjob has to rotate before beginning line
stretch. Most off-headings are already decided before line stretch occurs, by a rotation
of the packjob. Packjob rotation can be caused by countless variables:
• The packjob is influenced by the container walls due to bad body position.
Bridle Extension to Packjob Extraction
• An asymmetric or imbalanced packjob tilts or turns because one side is heavier or
more influenced by airflow.
BASE bridles should be at least nine feet in length from the pin or shrivel flap to PC.
This should allow the PC to extend beyond the worst of the jumper’s burble into clean
air, and also provides a long enough lag time for the PC to generate ‘snatch’ force with
which to extract the packjob from the container.
• The center cell is asymmetrically folded into the packjob, and when pulled by the PC,
tilts or rotates the packjob as a result.
The pilot chute alone is responsible for removing the canopy from the container and
bringing it to line stretch. Although the canopy itself will begin creating drag and
encouraging line stretch on its own once it has cleared the container, the pilot chute will
continue to serve its purpose until bottom surface expansion of the canopy has begun.
• Center cell strip caused by a too large PC seriously deforms the packjob, encouraging
asymmetric inflation.
This is where we see why pilot chute size is critical. A too large PC will cause excessive
center cell strip, which will deform the packjob, perhaps asymmetrically, and thus
negatively affect the opening and heading performance. A too small PC will increase
the timeline of the deployment process, leading to a critical loss of altitude, and will
• Wind, particularly in the case of low airspeed (short delays) deployments, affects the
packjob or causes the PC to pull from one side.
Once the packjob has been extracted from the container it will create drag and aid the
PC in line extension. Although the gradually unfolding packjob is creating drag, the
PC is still working at this point as well and plays an important role in the deployment
process until total line stretch is achieved.
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T H E G R E AT B O O K O F B A S E
ETHICS
CHAPTER 8
the leave no trace idea is that we don’t have to make anything any worse than it really
needs to be. We don’t need to drive to the store if we can walk in a reasonable amount
of time, and we don’t need to cut trees down to get a better movie shot.
On a less environmental note, the leave no trace theme is just as important at other
objects, where local jumpers will not benefit from the general public being made aware
of their actions. If you’re going to access the roof of your friend’s apartment building
downtown and jump from it, then the less people who find out about it, the better
your chances are that you’ll get to do it again. Leave no trace - no litter, no damage, no
stickers. It’s a simple rule.
Don’t Get Caught
There are countless legal objects in the world, enough to keep you busy for the rest
of your life without ever jumping the same one twice. So there is no good excuse to
get caught and possibly ruin access to an illegal object that other jumpers might be
enjoying safely and discretely. Jumping an illegal object and then getting caught is bad
for you, bad for the sport, and bad for everyone else in it. Try not to be that guy or girl
who ruins it for others – it is a small community and we will not let you forget your
carelessness any time soon. And you will deserve the jeering ostracism if you do. The
excitement of sneaking around at night is irresistable for many jumpers, so check out
the legality section just in case.
Who Is a BASE Jumper?
We are young, and we are old. We are professionals, and we are transient wanderers. We are doctors
and lawyers and firemen and train conductors. We are tradesmen and intellectuals, philosophers and
teenage thrill seekers. We are men, and we are women. Although we can estimate with some precision
that the majority of BASE jumpers are single males between the ages of 22 and 40, this sport attracts
men and women from all walks of life. I have jumped with a nurse, a race car driver, an airline pilot,
and a stuntman, all at the same time from a cliff in the Alps. Our common bond is a strong one, and
transgresses all other cultural or social boundaries. It is not uncommon to meet people from four or five
different countries at a single exit point, and for long-lasting friendships to form between people from
totally different parts of the world.
Don’t Get Injured (or Die)
Accidents suck. They suck for you most of all, they suck for your friends who have to
care for you or scrape your body off the ground, and they suck for everyone else in the
sport. It would be great if BASE jumping made the news for more positive reasons, but
at this point in time the vast majority of media coverage revolves around accidents and
illegal acts, which does little other than make us look like danger-craving criminals,
which we are not. Do your part to preserve yourself, and our image.
ETHICS
CHAPTER 8
Opening Objects
The whole world is jumpable,
almost. Once you have been
infected with the BASE
mindset, you will never
look at high objects the
same. Buildings, bridges,
cliffs… everywhere you look,
possibilities exist.
The fact is that quality
unjumped objects that
require less than a few days
walk or a long helicopter
flight are extremely rare.
This means that, if you are
looking at what you think is
a fantastic object, then the
chances are it has already
been jumped before or is
still being jumped regularly.
Do your research and find
the locals who will have the
necessary information to help
you jump the object safely.
If you have somehow
stumbled upon a quality
potential BASE object and
after extensive research, no
one seems to know anything
about it then it may be your
turn to “open” the object. Jhonny and Ren. Photo by Harry Parker.
This is something that is
generally left to the most experienced jumpers, and the knowledge required to do it
safely is far more than could fit within the pages of any book.
The basic rule is, again, to leave no trace. No matter the object, BASE jumping should
be a zero impact endeavor. We don’t leave mountain bike tire tracks, or climbing bolts
and chalk. We don’t need to mark our path or cut any trees. The environment need not
suffer for our presence.
After opening your object, you are faced with the decision of whether to tell everyone,
no one, or just the right people. Consider that the people you tell will certainly tell
others, and depending on the quality of the object its popularity will grow accordingly.
How much traffic can this object withstand before it becomes a liability to the sport,
and to you? Think carefully before spreading the word.
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T H E G R E AT B O O K O F B A S E
T H E G R E AT B O O K O F B A S E
PACKING TO PLF
CHAPTER 9
PACKING TO PLF
CHAPTER 9
From Packing To PLF
Packing
Your single parachute system must open and function correctly on every jump. If it
does not, the consequences will almost certainly be undesirable. Thus, packing is a
massive part of jumping, but many new jumpers let too much ride on their packjobs
and not enough on the other factors surrounding the opening of their parachutes. A
canopy that has been meticulously prepared over the course of an hour by a focused
jumper who chooses to use it in high winds will not necessarily open better than a 10
minute ‘trash-pack’ jumped with good body position in the right conditions. Plenty of
rapid and careless packjobs have opened perfectly, and plenty of perfect packjobs have
ended in disaster. Therefore, while clean and careful packing should be considered
mandatory, it is also important to understand all of the factors which determine the
outcome of your opening.
Learn the Details
Immerse yourself in packing, and understand the process completely. The more you understand
about packing technique, the greater your awareness will be of the relationship between you and your
equipment.
The key to packing, perhaps, is to find your balance of speed and meticulousness, and
to understand that factors such as weather and body position make up a large part of
the links in the chain of a safe parachute opening. Most experienced jumpers use the
broad and totally generalized estimation that body position is around 80% of opening
performance, with the majority of the remaining 20% reliant on packing and weather
factors. However, that is assuming all factors are normal, including weather conditions.
If you take your perfect packjob off a cliff with perfect body position in turbulent wind
conditions, then the probability of a clean opening is dramatically reduced, and most
would agree that a 180 or worse would come as no surprise. Additionally, if one of
those quick and careless packjobs opened with a malfunction, even in the possession
of a veteran in perfect conditions, no one would be surprised. If packing carelessly
or jumping in sub-optimal conditions works 99 out of 100 times, and failure means
serious injury or death, are those odds that you want to play? You shouldn’t, if you
want to live a long healthy life, and the case for packing carefully and choosing good
conditions is clear cut. Don’t allow the process of packing your rig become a tedious
chore. If you can’t learn to enjoy it, at least accept it as an essential and unavoidable
part of perhaps the most amazing activity that you can ever engage in. Before you start,
consider the following points.
Focus
Choose an environment that is comfortable and free of distractions: The surface
should be clean not hard or slippery. Shag carpet, for instance, is far preferable to hard
tile; kneeling on tile or concrete isn’t fun, and your canopy and container will slide
*Assuming reasonably appropriate jumping conditions. Note that totally inappropriate weather may
override all other factors.
**Assuming appropriate, modern, quality equipment. Note that outdated or poorly maintained or
assembled equipment may override all other factors.
Also, the Packing slice shown above assumes reasonably clean and correct packing. Note that terrible
or incorrect packing will override other factors.
Consistency is Key
If you always pack the same, then when something irregular does occur, you can potentially remove the
packing variable as a major cause of the result.
around and it will be more difficult to maintain line tension. Manicured green grass is
a favorite surface for many jumpers. It is soft, the rig is not prone to slide, and you can
often use a stake instead of packing weights.
Particularly during your first hundred packjobs, you should try to pack someplace
where you won’t be interrupted or distracted from your task. If you find a nice grassy
spot near a horde of attractive sunbathers that you can’t keep your eyes off, maybe
choose another spot. If ten of your non-jumping friends are admiring your newfound
bravery and skill and wondering at the gravity of your project, ask them to not talk to
you until you’ve completely finished everything. If they ask you a question and you stop
to answer it, and then forget a step, then you won’t be the first person to fold tools into
the container, or to forget another important step that could lead to a fatality. Simple,
stupid, basic packing errors can kill.
Prepare in the Appropriate Environment
Before you begin packing, be sure that you have everything you need close at hand. You
shouldn’t have to go and find a pull up cord or a clamp or a tailgate halfway through
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T H E G R E AT B O O K O F B A S E
MOAB
Moab: Subterminal Paradise
By Steph Davis
If you like slickrock, low cliffs and no hassles, you will probably like jumping in Moab.
If you also happen to like rock climbing, camping, mountain biking, river rafting,
paragliding, speed flying, skydiving, rock hounding, canyoneering, trail running,
motocross, skiing and/or drinking beer that’s not too strong, then you’ll probably move
here. It’s no exaggeration to call Moab a sub-terminal BASE paradise.
Moab, a town of 5,000 locals, is home to around four local BASE jumpers, just as in
the early days. But it is now a major destination. A Cessna skydiving operation fills
in the gap for those craving terminal altitude and can help relieve the disappointment
of being winded out. Many exits can be reached in under an hour, though simple to
difficult scrambling can occasionally be required and sometimes even roped technical
climbing is necessary. Three to four hundred foot cliffs are the norm, though you can
find plenty of 200-footers, if that’s what you’re into. The ease of access, the beauty of the
visuals, and the completely hassle-free lifestyle of Moab make the sub-terminal world
pretty addictive.
It’s hard to say who did the
first jumps in Moab. Alf
Humphries was most likely
the first. From 1991-3, he
opened several exits with a
small crew. Kevin McGuire
did the first jump from the
Tombstone, the most wellknown cliff in Moab. In the
early 90’s, word spread around
to other jumpers when a
few BASE videos of Dennis
McGlynn started to appear.
He was jumping beautiful red
cliffs with vague references to
location. Almost every other
place with steep, accessible
cliffs in America seemed to
concoct rules against it as
soon as jumpers appeared.
So the first Moab visitors
were torn by the urge to share
and the instinct to keep it on
the down low.
By 1999 there were a handful
of known exits, though
Steph at Tombstone. Photos by Diego Calderoni.
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WEATHER TO BASE
CHAPTER 11
WEATHER TO BASE
CHAPTER 11
Mechanical Turbulence
Wind interacting with terrain and objects creates mechanical turbulence. This is a
readily understandable situation; much like the currents in a river which eddy and
turbulate behind rocks, the leeward side of objects will almost without exception
feature turbulent air.
Higher wind will create more turbulence, and because high wind is not conducive to
safe BASE jumping, mechanical turbulence is not something that you should encounter
very often, or ever, if you choose your conditions responsibly. However, a classic
example would be an acceptable amount of valley wind in the landing zone several
thousand feet below an exit point in light or no wind. Obstacles in the valley such
as trees or buildings can create turbulence downwind that, even in winds as light as
10-15mph, can make landing conditions less than ideal. Understanding rotor can save
you from injury or worse.
The diagrams below and top right show that turbulence extends downwind of an object
for increasing distances in higher winds. It should be obvious that landing downwind of
uneven terrain, trees, or manmade obstacles is far less preferable to landing in clean air.
Although BASE canopies are all relatively resistant to collapse, you can still suddenly
lose altitude due to sinking air, or experience large pitch oscillations which will require
brake input and reduce airspeed and flare energy needed close to the ground. Use
this knowledge to choose
your landing zone ahead
of time, and plan ahead.
Mechanical turbulence in the mountains. Atmospheric wind is compressed at
ridges and peaks, then turbulates in the rotor on the leeward side. Depending
on the strength of the wind, jumping in the lee can be a very bad idea - canopy
flight and landings will be turbulent and unpredictable, and wingsuit flights
can also be affected.
Valley Winds Caused by Anabatic or Catabatic Flow
As the sun heats mountainsides and thermals lift, wind will be drawn through the
valleys to replace the heating air. Valley wind is not always caused by atmospheric
wind; the wind at altitude can be calm while, at the same time, solar heating is
causing a strong valley breeze. This is an important distinction.
(At Left) Building induced turbulence, side
view. Wind compresses at top edge, turbulates
over the top and also behind. Turbulence also
extends to ground level, and would appear as
illustrated at right.
Valley “wind” can actually be caused by solar heating and is better referred
to as the anabatic flow. Atmospheric wind may not be related to valley flow,
although the two may influence each other. For instance, if the atmospheric
wind depicted in this figure were to change 90 degrees and orient itself to
match the valley flow, then the valley flow could be positively influenced
by the atmospheric wind, and would generally become stronger and more
turbulent. Similarly, an atmospheric wind can combat or block an anabatic
flow, and vice versa.
(At Right) Building induced turbulence, top view. Wind
compresses at the edges and turbulates around the sides
and also behind. Jumping buildings in wind is a bad idea.
Wait for no wind.
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T H E G R E AT B O O K O F B A S E
T H E G R E AT B O O K O F B A S E