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U£Department 

ofTransportation 

Federal Aviation 

Administration 

Powerlines 

FAA-P-8740-34 

AF0-800-0581 

and Thunderstorms 

Balloon Safety Tips . 

aeeident prevention program. 
FOREWORD 

The purpose of this series of publications is to provide the general 

aviation flying public with information that may improve aircraft 

operational safety. Because of the increasing activity in balloon 

operations. and the increase in accidents involving balloons, safety tips for 

balloon pilots will be included in the Accident Prevention Program 

pamphlet series. This particular pamphlet identifies certain hazards 

associated with the operation of hot air balloons and provides suggested 

safety procedures to minimize the accident potential. 

ACKNOWLEDGEMENT 

The articles included in this pamphlet were contributed by the 

Albuquerque Aerostat Ascension Association. Mr. Robert L. Ruppenthal 

has written several safety articles on ballooning and he is a former Chief 

Design Engineer for Research and Development for Thunder Hot-Air 

Balloons. Also included are articles from "Raven Owners Newsletters" 

published by Raven Industries. Inc. The Federal Aviation Administration 

appreciates the contribution of these articles by the Albuquerque Aerostat 

Ascension Association and Raven Industries. Inc .. tor use in the Accident 

Prevention Program. 

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A New Problem Emerges To Complicate Traditional Hazards 

This article is addressed expressly to experienced balloonists, (pilots. crew and 

friends). The information in the article is 

presented as information concerning possible 

hazards. Discussion of hazards is an effective 

way to reduce or eliminate their occurrence. 

Unfortunately, the frank presentation of facts 

could create the wrong impression to new enthusiasts. The actual incidence of the type of 

accident specifically referred to in this article 

is perhaps one in one-half million operations. 

However, the gravity of this accident is such 

that any incidence of this accident is unsatisfactory. Traditional hazards of fire and 

power line collision can be even more 

dangerous if your balloon envelope has a selfclosing def.lation valve. 

Fatal accidents have occurred where the 

balloon envelope was uncontrollably heated by 

a large on-board fire, thereby resulting in a 

more serious accident than the fire alone might 

have created. Self-closing valves require constant restraint to deflate the envelope. Pilots and 

crew cannot, in every case, function continuously during a large fire to insure that the 

balloon envelope deflates as fast as possible in 

order to reach the safety of the ground. The inability to exhaust the envelope heat created by 

a large on-board fire causes the envelope to ascend to altitudes beyond the safe level which 

the occupants can ·abandon the balloon. 

There may be a number of methods to overcome this problem. Certainly a system of securing the valve line in an open position together 

with a fire resistant (steel core) line are the principal areas which need study. Many good.ideas 

will be advanced as corrective measures, and a 

few will be produced as actual hardware. · 

However. hardware 1s not the purpose of this 

article. My purpose is to make the reader aware 

of the problem and the obviously serious 

results. 

I am not advocat1ng the the self-closing 

deflation valves. available· from almost all 

balloon manufacturers. be shunned as 

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dangerous. I have maintained for a long period 

of time that in terms of over-all safety that the 

self-closing valves are inherently superior to 

valves which cannot be reclosed by the pilot 

while in flight. The safety of non-reclosing 

valves has been very good; however, the basic 

reasons which caused serious accidents with 

non-reclosing valves still exists-only constant 

attention to maintenance details cause them to 

be safe. Prevention of the circumstances that 

cause massive on-board fires is the obvious 

best solution to the problem. 

The three accidents of which I am aware involving on-board fires, self-closing deflation 

valves and fatal conclusions had different 

original circumstances. The original cause of 

one accident was a break in the main fuel 

system piping. Two accidents were caused by 

rupture of the fuel system from power line collisions. 

Balloon fuel systems are not well protected 

because the design must accommodate the 

necessity to remove major components of the 

system for storage (i.e., burners, tanks and 

hoses). Some manufacturers have better 

designs than others; however, there is no current design which fully protects the fuel system 

from all the possible abuse which can occur in 

balloon operation. Ultimately, the pilot must 

take responsibility for the safety of the fuel 

system. The area of greatest concern is that the 

system resist a major fuel line or valve break. A 

major leak in a high pressure propane system is 

an opening approximately twice the diameter 

of a common pin. It is important that fuel hose 

arrangements be protected from the balloon 

occupants particularly at connections to tank 
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valves. Short pieces of pipe associated with 

quick disconnects at the tank valves or for any· 

other reason must be carefully protected 

(usually by rotating the tank until the fitting is 

protected by the gondola structure) from heavy 

body contact by the pilot or passengers. These 

short pieces of pipe act as levers which multiply 

the force of the blow on the valve body. It is possible to break tank valves in this manner. Brass 

fittings have only % the strength of steel for an 

equal thickness; therefore, these fittings are the 

most suspect and require special attention. 

Fuel tanks can be burned through by arcing 

power lines. It is unlikely that a pilot can do 

much to protect tanks from this exposure except by avoiding power lines. 

1 he hazard of power lines 1S generally acceptetJ as balloor11ng s greatest danger. Contacting power lines below the equator of the 

envelope will generally result 1n · burn1ng 

through the flyrng wnes as the envelope drags 

tt1e gondola over tLn wires If contact IS made 

at or below the supr,rstruc;ture a good chance 

of a fuel tank or turd l1ne rupture ex1st_s from 

power lrne arc1ng. Ne1ther oi these alternatives 

IS acceptable Powor 1rne contact above the 

equator 1s much less hazardous because the 

balloon Will be forcr;d to the ground by a combina\lon of the otJ'otl uctron and w1nd force. 

Therrn1c: conli1t1or•, may complicate ttw last 

option. 

Obv1ously :r1e best way ·to promote your personal safety {in~ludHlQ pas~.engers) 1s tc avoid 

power lrnes Avoidance of power lines. wh1le 

highly desirable, will not always be possible. 

Each of us will at some time in our balloon flying career make a serious in-flight decision 

about power line contact. This decision will be 

hard, perhaps terrifying and very serious. 

Knowing that collision with a power line 

must occur in a precise way in order to 

minimize personal injury is a big part of the 

decision criteria. Acting quickly is also 

necessary. The decision involves "burn" or 

"rip". Emotionally, all pilots will want to "burn" 

because if you can fly over the wires-missing 

them completely-there are no complications 

once safe passage occurs. The nagging prob· 

lem is predicting absolutely that you can clear 

the power lines. On the other hand, ripping is a 

safer decision because there is almost no 

chance that the envelope will contact the 

power line incorrectly, r.e. below the equator. 

-- The· ·problems- with ripping are- numerous; 

however, these problems are not as likely to be 

fatal. 

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Consider the possible problems of rrpping: 

a. The prlot"s ego may be severely wounded 

because there 1S tt1e possrb1lrty of criticism for 

over reactrng. On the other hand. it may be nice 

to be a11ve and capable of personally drscussing thrs critiCISm. 

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b. The balloon envelope may sustain damage 

from the power lines. Consider the fact that 

your insurance company will be very pleased to 

pay for envelope damage as opposed to 

passenger liability. 

c. There is a chance that there could be injury 

to the pilot or passengers. Properly prepared 

for a heavy landing there is really very little 

chance of serious injury. A balloon ripped from 

150 feet cannot exceed 1500 feet per minute 

descent rate. Landing at 1500 feet per minute is 

a hard jolt that can be successfully handled 

without injury. 

d. Like any hard landing the fuel should be 

secured and the pilot light extinguished before 

ground contact. 

There are other possible problems such as 

rebound that could occur. Thinking out the 

problem in advance of a real power line collision threat will give the pilot more confidence 

to make the correct decision. 

For safe flying ..... 

Bob Ruppenthal 

Powerline Safety 

Recently, two Colorado pilots were forced to 

jump from their balloon just before it plowed 

into powerlines. They were not injured, but the 

balloon received extenstve damage. Also 

recently, a balloon hit a powerline in Kansas 

City. It was damaged. but there were no injuries 

to the balloonists. And in east Texas, a balloon 

recently deflated across powerlines at sun· 

down. The pilot received minor burns and so 

did the balloon, but the two passengers 

escaped uninjured. ,Again in east Texas, a 

balloon was caught in the wind shear du.ring a 

landing in a new subdivision and became entangled in some wires that fortunately were not 

alive with electricity. There were no damages or 

mjuries. A balloonist and h1s· passenger were 

not so lucky m Wichita last month. They were 

killed when the" superpressurized balloon 

broke 1ts tether and sailed off into powerlines. 

When a long electncal cord hanging down from 

the ·basket contacted 69 KV lines, the two 

occupants suffered severe electrical burns, 

became unconscious, fell out of' the basket, 

and were pronounced dead by electrocution. 

Each of the.se powerline a·ccidents h.as its 

own set of circumstances and causes for hap5 

pening. Regardless, each deals a severe blow 

to the safety record of the entire ballo.oning 

community. For this reason, if for no other, it is 

paramount that all pilots take steps to avoid 

collision with powerlines. Towards this goal, 

some advice and discussion is offered through 

this newsletter media. 

Just what can happen? If a balloon coniacts 

powerlines at the basket, it is possible that the 

occupants touchtng any part of the metal 

superstructure or fuel system can be electrocuted. Such contact could also result in fire 

and explosion if hot wires penetrate a tank or 

fuel line. If a balloon makes contact with its 

suspension cables, the resultant arcing can 

sever the_cables. The occupants are left in free 

fall, either with the basket or on their own. Con· 

tact at the envelope may cause fabric melting, 

partial deflation and some electrical power 

transmission to the basket by way of the rip 

line, damp load tapes. or the pyrometer cable. 

All of these accidents can be avoided if proper 

care and precautions are taken. 

During launct1ing, powerlines are avoidable 

simply by launching downwind of the wires or 

at a safe distance upwind of the wires. This is 
just common sense and applies to tethering as 

well. For crossing powerlines downwind of the 

launch site, a good rule of thumb is to allow at 

least 100 feet of horizontal separation between 

the lines and the balloon for each knot of wind 

speed. For example, in a 1 0-knot surface wind, 

the launch site should be at least 1,000 feet 

upwind. But be conservative in your 

estimates-1500 feet would be even better. The 

actual crossing should be made with several 

hundred feet of vertical clearance. It is even 

advisable to cross the line in an ascent. Pay 

attention to how heavily loaded the balloon is 

and quickly assess your balloon's ability to 

climb under the currect conditions. Overloaded 

balloons tend to be sluggish and very slow 

reacting. Don't forget-an average balloon has 

over two tons of inertia! 

Do not attempt landings upwind of 

powerlines without employing the above 

distance minimums. Better yet, it just makes 

good sense not to make landings upwind of 

powerlines at all; instead, cross them at a safe 

altitude and select a more appropriate landing 

site. If winds are gusty, thermic or otherwise 

unstable, be especially cautious. Under such 

conditions, the direction and altitude of the 

balloon can change abruptly and safety 

margins can dwindle in seconds. 

In level flight, keep a constant vigil for 

powerlines. They are not easy to see from the 

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air, especially when viewed against a mixed(~" 

background of earth and vegetation. If the wind\ ) 

dies and the balloon is suddenly becalmed over ·---

powerlines, climb to a higher altitude to find a 

wind that will move the balloon aside. If no 

such lateral movement is discovered, carefully 

use a drop line and an experienced ground crew 

tci pull the balloon out of danger. Keep -in mind 

that hemp and nylon, under certain conditions, 

have been known to conduct over 500 volts. 

Whenever ballooning in the vicinity of 

powerlines, use every precaution possible. 

Don't take chances. Don't tempt the destructive potential (no pun intended) of such 

innocent-looking wires. Things can happen very 

quickly and a not-so-bad situation can rapidly 

deteriorate into a gruesome ordeal. Balloonists 

right now are pushing their luck. Flights are 

getting sloppy and accidents are happening. 

For your own safety, the safety of your trusting 

passengers, and the reputation of the great 

sport of ballooning, be more careful. 

Raven Owners Newsletter () 

Summer Safety in the Storm and Thermal Season 

To avoid tragic weather-related experiences 

in ballooning, it helps to have some knowledge 

of summer thunderstorms and thermals. Never 

attempt the destructive potential of either 

phenomenon. 

At 12,000 to 16,000 feet, small cumulus 

(building) clouds of summer flourish and grow 

rapidly to large towering (20,000 to 60,000 feet) 

cumulonimbus thunderstorm clouds. Surprisingly, an-afternoon thermal or small orographic 

disturbance can trigger the development of a 

thunderstorm by initiating the :rise of warm 

moist air. Most severe thunderstorm developnient occurs along or just ahead of summer 

cold fronts. They materialize in a squall line 

several hundred miles long at times. Invariably, 

there is a continuous line of strong gusty 

winds, violent updrafts and downdrafts 

sometimes in excess of several thousand feet 

per minute. wind shear turbulence, thunder roll, 

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'lightning strokes, hail, heavy rainfall, and even 

flash floods. Some of the more ferocious 

storms also spawn tornadoes. Obviously, these 

are not conditions suitable for balloon flying. 

It should be noted that there is still much 

unknown about just how thunderstorms 

operate. For instance, scientists still do not 

fully understand what causes lightning and its 

close association with rain. Some think lightning ·serves as a catalyst in the formation of 

rain while others believe that the rapid descent 

of charged rain or hail generates lightning. 

Here in the U.S., winds gusting to 60 and 70 

mph are oiien observed, usually moving from 

west to east or from northwest to southeast. 

Radar studies show the thunderstorm life 

cycle, from start of growth through maturity to 

dissipation, to be very short and somewhat 

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municate short term storm details to remote 

locations-often the locations where ballooning takes place. By the very nature of the 

storm's behavior, one area may be missed 

while another may experience high winds and a 

torrential downpour. This is why balloonists 

must keep a watchful eye for a rapidly darkening western or south-western sky followed by 

distant thunder and lightning, as well ~s local 

irregular shifts in wind speed and direction. 

Such symptoms provide approximately 30 

minutes of advance warning. Dust on the 

horizon signals the onset of gusty surface 

winds of the encroaching storm determined by 

observing the direction of the anvil-shaped 

cloud blowing out ahead of the system. 

Peak gusts of a raging thunderstorm strike 

abruptly and leave little time for a safe landing. 

Even airplanes have broken up in flight several 

miles from a storm, so one can just imagine 

what could happen to a relatively frail balloon. 

A thunderstorm is said to reach maturity 

when rain begins to fall. Since the storm is 

essentially vertical the falling rain penetrates 

the clouds and its aerodynamic drag creates 

downdrafts. Each drop causes more drops to 

precipitate and some air is dragged downward. 

The result is a mass of downrushing air that 

turns at right angles when it reaches the sur· 

face and then spreads out away from the col· 

umn of heavy precipitation. Most of the 

downrushing air turns in the direction of the 

overall storm movement, creating a gust front 

that could cause a Jot of excitement for the unwary balloon pilot. 

Even though thunderheads may be. seen to 

be forming in the distance, the balloonists can 

easily be tempted to continue flying in gentle 

surface winds. However, cumulonimbus clouds 

can affect. wind currents as far away as ten 

miles with abrupt changes. The balloon can 

actually be drawn into the storm center as 

warm moist air flows inward ·toward the rising 

vertical columns of air. It is therefore highly advisable to never venture closer than ten miles. 

Instead, land and terminate all ballooning activity for the day. 

Summertime is also thermal season and it 

would be wise for all balloonists to respect the 

sun-generated weather phenomenon known as 

the thermal. When the lower atmosphere is 

heated and the lapse rate of air becomes dryadiabatic, the conditions are ideal. 

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Surfaces with low solar reflectivity and with 

shelter from the wind are the most likely 

breeding grounds. Calm conditions promote 

thermals by allowing more time for isolated or 

sheltered pockets of air to be solar-heated. 

Here, more heat energy is provided than the 

surface can absorb. The extra heat is trans· 

!erred to the air by convection, causing it to 

become buoyant. As the bubble of superheated 

air rises, it displaces the air above it, forcing it 

into an unstable condition. Under these condi· 

lions, as thermals form, a balloon's drift may be 

abruptly shifted in speed and direction without 

a change in altitude or it may begin to trace a 

wide curved path. These are the first signs of 

thermal activity. Southeast-facing slopes have 

greater potential for thermal development than 

flat terrain because of the higher sun angles, 

thus permitting more solar heating. Thermals, 

like balloons, tend to drift with the wind (so one 

may ride along with it for a while), but break up 

when the wind speed exceeds 15-20 knots. 

Like in the case of the thunderstorm, a 

balloon can be drawn into the center of a ther· 

mal where the action of the vortex can cause 

the basket to swing outward beneath the 

envelope as the balloon traces a spiraling path 

that climbs at an alarming rate, perhaps more 

than 1000 fpm. This is false climb since no heat 

was added to the envelope by the burners. The 

pilot must anticipate a sudden loss of-lift and a 

potential downdraft when the balloon pops out 

of the thermal. Heat should be applied to offset 

a rapid uncontrolled descent. The flatt<;lning 

and distorting stresses on the top panel could 

cause an inadvertent ripout at high altitude or 

the side panels could split open. For this 

reason, the first sign of thermal activity should 

herald the end of ballooning for that day. 

Remember that in the summer mqnths, the 

sun rises earlier and heats the ground sooner. 

Sun angles are. high therefore the morning 

flight hours are reduced, especially when the 

air is clear, dry and calm. Fortunately, weak 

thermals. precede more powerful thermals. The 

unstable conditions during early thermal 

development normally warn the pilot of the 

pending danger, but only if he is alert to subtle 

changes in his balloon's behavior. 

"Raven Owners Newsletter" 
SAFE FLYING 

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