Document
FAA-P-8740-34 AF0-800-0581
Powerlines
U£Department ofTransportation
and Thunderstorms
Federal Aviation Administration Balloon Safety Tips .
aeeident prevention program.
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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 ex- dangerous. I have maintained for a long period perienced balloonists, (pilots. crew and of time that in terms of over-all safety that the friends). The information in the article is self-closing valves are inherently superior to presented as information concerning possible valves which cannot be reclosed by the pilot hazards. Discussion of hazards is an effective while in flight. The safety of non-reclosing way to reduce or eliminate their occurrence. valves has been very good; however, the basic Unfortunately, the frank presentation of facts could create the wrong impression to new en- thusiasts. 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 un- satisfactory. Traditional hazards of fire and power line collision can be even more reasons which caused serious accidents with dangerous if your balloon envelope has a self- non-reclosing valves still exists-only constant closing def.lation valve.
attention to maintenance details cause them to be safe. Prevention of the circumstances that Fatal accidents have occurred where the cause massive on-board fires is the obvious balloon envelope was uncontrollably heated by best solution to the problem.
a large on-board fire, thereby resulting in a more serious accident than the fire alone might The three accidents of which I am aware in- j have created. Self-closing valves require cons- volving on-board fires, self-closing deflation tant restraint to deflate the envelope. Pilots and valves and fatal conclusions had different crew cannot, in every case, function con- original circumstances. The original cause of tinuously during a large fire to insure that the one accident was a break in the main fuel balloon envelope deflates as fast as possible in system piping. Two accidents were caused by order to reach the safety of the ground. The in- rupture of the fuel system from power line colli- ability to exhaust the envelope heat created by sions.
a large on-board fire causes the envelope to as- Balloon fuel systems are not well protected cend to altitudes beyond the safe level which because the design must accommodate the the occupants can ·abandon the balloon.
necessity to remove major components of the There may be a number of methods to over- system for storage (i.e., burners, tanks and come this problem. Certainly a system of secur- hoses). Some manufacturers have better ing the valve line in an open position together designs than others; however, there is no cur- with a fire resistant (steel core) line are the prin- rent design which fully protects the fuel system cipal areas which need study. Many good.ideas from all the possible abuse which can occur in will be advanced as corrective measures, and a balloon operation. Ultimately, the pilot must few will be produced as actual hardware. · take responsibility for the safety of the fuel However. hardware 1s not the purpose of this system. The area of greatest concern is that the article. My purpose is to make the reader aware system resist a major fuel line or valve break. A of the problem and the obviously serious major leak in a high pressure propane system is results.
an opening approximately twice the diameter of a common pin. It is important that fuel hose I am not advocat1ng the the self-closing arrangements be protected from the balloon deflation valves. available· from almost all occupants particularly at connections to tank balloon manufacturers. be shunned as highly desirable, will not always be possible.
valves. Short pieces of pipe associated with Each of us will at some time in our balloon fly- quick disconnects at the tank valves or for any· ing career make a serious in-flight decision other reason must be carefully protected about power line contact. This decision will be (usually by rotating the tank until the fitting is
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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· protected by the gondola structure) from heavy lem is predicting absolutely that you can clear body contact by the pilot or passengers. These the power lines. On the other hand, ripping is a short pieces of pipe act as levers which multiply safer decision because there is almost no the force of the blow on the valve body. It is possi- ble 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 ex- cept by avoiding power lines.
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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.
Consider the possible problems of rrpping: 1 he hazard of power lines 1S generally ac- ceptetJ as balloor11ng s greatest danger. Con- tacting 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 com- :i bina\lon of the otJ'otl uctron and w1nd force.
' Therrn1c: conli1t1or•, may complicate ttw last a. The prlot"s ego may be severely wounded option.
because there 1S tt1e possrb1lrty of criticism for Obv1ously :r1e best way ·to promote your per- over reactrng. On the other hand. it may be nice sonal safety {in~ludHlQ pas~.engers) 1s tc avoid to be a11ve and capable of personally drscuss- power lrnes Avoidance of power lines. wh1le ing thrs critiCISm.
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
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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 colli- sion threat will give the pilot more confidence to make the correct decision.
b. The balloon envelope may sustain damage For safe flying .....
from the power lines. Consider the fact that Bob Ruppenthal Powerline Safety Recently, two Colorado pilots were forced to pening. Regardless, each deals a severe blow jump from their balloon just before it plowed to the safety record of the entire ballo.oning into powerlines. They were not injured, but the community. For this reason, if for no other, it is balloon received extenstve damage. Also paramount that all pilots take steps to avoid collision with powerlines. Towards this goal, recently, a balloon hit a powerline in Kansas City. It was damaged. but there were no injuries some advice and discussion is offered through to the balloonists. And in east Texas, a balloon this newsletter media.
recently deflated across powerlines at sun· Just what can happen? If a balloon coniacts down. The pilot received minor burns and so powerlines at the basket, it is possible that the did the balloon, but the two passengers occupants touchtng any part of the metal escaped uninjured. ,Again in east Texas, a superstructure or fuel system can be elec- balloon was caught in the wind shear du.ring a trocuted. Such contact could also result in fire landing in a new subdivision and became en- and explosion if hot wires penetrate a tank or tangled in some wires that fortunately were not fuel line. If a balloon makes contact with its alive with electricity. There were no damages or suspension cables, the resultant arcing can mjuries. A balloonist and h1s· passenger were sever the_cables. The occupants are left in free not so lucky m Wichita last month. They were fall, either with the basket or on their own. Con· killed when the" superpressurized balloon tact at the envelope may cause fabric melting, broke 1ts tether and sailed off into powerlines.
partial deflation and some electrical power When a long electncal cord hanging down from transmission to the basket by way of the rip the ·basket contacted 69 KV lines, the two line, damp load tapes. or the pyrometer cable.
occupants suffered severe electrical burns, All of these accidents can be avoided if proper became unconscious, fell out of' the basket, care and precautions are taken.
and were pronounced dead by electrocution.
During launct1ing, powerlines are avoidable Each of the.se powerline a·ccidents h.as its simply by launching downwind of the wires or own set of circumstances and causes for hap- at a safe distance upwind of the wires. This is .·J···.·.; > ' just common sense and applies to tethering as In level flight, keep a constant vigil for well. For crossing powerlines downwind of the powerlines. They are not easy to see from the launch site, a good rule of thumb is to allow at air, especially when viewed against a mixed(~" least 100 feet of horizontal separation between background of earth and vegetation. If the wind\ ) dies and the balloon is suddenly becalmed over ·--- the lines and the balloon for each knot of wind speed. For example, in a 1 0-knot surface wind, powerlines, climb to a higher altitude to find a the launch site should be at least 1,000 feet wind that will move the balloon aside. If no upwind. But be conservative in your such lateral movement is discovered, carefully estimates-1500 feet would be even better. The use a drop line and an experienced ground crew actual crossing should be made with several tci pull the balloon out of danger. Keep -in mind hundred feet of vertical clearance. It is even that hemp and nylon, under certain conditions, advisable to cross the line in an ascent. Pay have been known to conduct over 500 volts.
attention to how heavily loaded the balloon is Whenever ballooning in the vicinity of and quickly assess your balloon's ability to powerlines, use every precaution possible.
climb under the currect conditions. Overloaded Don't take chances. Don't tempt the destruc- balloons tend to be sluggish and very slow tive potential (no pun intended) of such reacting. Don't forget-an average balloon has innocent-looking wires. Things can happen very over two tons of inertia!
quickly and a not-so-bad situation can rapidly Do not attempt landings upwind of deteriorate into a gruesome ordeal. Balloonists powerlines without employing the above right now are pushing their luck. Flights are distance minimums. Better yet, it just makes getting sloppy and accidents are happening.
good sense not to make landings upwind of For your own safety, the safety of your trusting powerlines at all; instead, cross them at a safe passengers, and the reputation of the great altitude and select a more appropriate landing sport of ballooning, be more careful.
site. If winds are gusty, thermic or otherwise unstable, be especially cautious. Under such conditions, the direction and altitude of the Raven Owners Newsletter balloon can change abruptly and safety margins can dwindle in seconds.
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Summer Safety in the Storm and Thermal Season To avoid tragic weather-related experiences 'lightning strokes, hail, heavy rainfall, and even in ballooning, it helps to have some knowledge flash floods. Some of the more ferocious of summer thunderstorms and thermals. Never storms also spawn tornadoes. Obviously, these are not conditions suitable for balloon flying.
attempt the destructive potential of either phenomenon.
It should be noted that there is still much At 12,000 to 16,000 feet, small cumulus unknown about just how thunderstorms (building) clouds of summer flourish and grow operate. For instance, scientists still do not rapidly to large towering (20,000 to 60,000 feet) fully understand what causes lightning and its cumulonimbus thunderstorm clouds. Surpris- close association with rain. Some think light- ingly, an-afternoon thermal or small orographic ning ·serves as a catalyst in the formation of disturbance can trigger the development of a rain while others believe that the rapid descent thunderstorm by initiating the :rise of warm of charged rain or hail generates lightning.
moist air. Most severe thunderstorm develop- Here in the U.S., winds gusting to 60 and 70 nient occurs along or just ahead of summer mph are oiien observed, usually moving from cold fronts. They materialize in a squall line west to east or from northwest to southeast.
several hundred miles long at times. Invariably, Radar studies show the thunderstorm life there is a continuous line of strong gusty cycle, from start of growth through maturity to winds, violent updrafts and downdrafts dissipation, to be very short and somewhat sometimes in excess of several thousand feet per minute. wind shear turbulence, thunder roll, complex. It is difficult to forecast and com- -~J
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Surfaces with low solar reflectivity and with municate short term storm details to remote locations-often the locations where balloon- shelter from the wind are the most likely ing takes place. By the very nature of the breeding grounds. Calm conditions promote thermals by allowing more time for isolated or storm's behavior, one area may be missed while another may experience high winds and a sheltered pockets of air to be solar-heated.
torrential downpour. This is why balloonists Here, more heat energy is provided than the must keep a watchful eye for a rapidly darken- surface can absorb. The extra heat is trans· ing western or south-western sky followed by !erred to the air by convection, causing it to distant thunder and lightning, as well ~s local become buoyant. As the bubble of superheated irregular shifts in wind speed and direction. air rises, it displaces the air above it, forcing it Such symptoms provide approximately 30 into an unstable condition. Under these condi· minutes of advance warning. Dust on the lions, as thermals form, a balloon's drift may be horizon signals the onset of gusty surface abruptly shifted in speed and direction without winds of the encroaching storm determined by a change in altitude or it may begin to trace a observing the direction of the anvil-shaped wide curved path. These are the first signs of cloud blowing out ahead of the system. thermal activity. Southeast-facing slopes have greater potential for thermal development than Peak gusts of a raging thunderstorm strike flat terrain because of the higher sun angles, abruptly and leave little time for a safe landing.
thus permitting more solar heating. Thermals, Even airplanes have broken up in flight several like balloons, tend to drift with the wind (so one miles from a storm, so one can just imagine may ride along with it for a while), but break up what could happen to a relatively frail balloon.
when the wind speed exceeds 15-20 knots.
A thunderstorm is said to reach maturity when rain begins to fall. Since the storm is Like in the case of the thunderstorm, a essentially vertical the falling rain penetrates balloon can be drawn into the center of a ther· the clouds and its aerodynamic drag creates mal where the action of the vortex can cause downdrafts. Each drop causes more drops to the basket to swing outward beneath the precipitate and some air is dragged downward.
envelope as the balloon traces a spiraling path The result is a mass of downrushing air that that climbs at an alarming rate, perhaps more 0 turns at right angles when it reaches the sur· than 1000 fpm. This is false climb since no heat face and then spreads out away from the col· was added to the envelope by the burners. The umn of heavy precipitation. Most of the pilot must anticipate a sudden loss of-lift and a downrushing air turns in the direction of the potential downdraft when the balloon pops out overall storm movement, creating a gust front of the thermal. Heat should be applied to offset that could cause a Jot of excitement for the un- a rapid uncontrolled descent. The flatt<;lning wary balloon pilot. and distorting stresses on the top panel could cause an inadvertent ripout at high altitude or Even though thunderheads may be. seen to the side panels could split open. For this be forming in the distance, the balloonists can reason, the first sign of thermal activity should easily be tempted to continue flying in gentle herald the end of ballooning for that day.
surface winds. However, cumulonimbus clouds can affect. wind currents as far away as ten Remember that in the summer mqnths, the miles with abrupt changes. The balloon can sun rises earlier and heats the ground sooner.
actually be drawn into the storm center as Sun angles are. high therefore the morning warm moist air flows inward ·toward the rising flight hours are reduced, especially when the vertical columns of air. It is therefore highly ad- air is clear, dry and calm. Fortunately, weak visable to never venture closer than ten miles. thermals. precede more powerful thermals. The Instead, land and terminate all ballooning ac- unstable conditions during early thermal development normally warn the pilot of the tivity for the day.
pending danger, but only if he is alert to subtle Summertime is also thermal season and it changes in his balloon's behavior.
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 dry- "Raven Owners Newsletter" adiabatic, the conditions are ideal.