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 powerline collision can be even more dangerous
if your balloon envelope has a self-closing deflation 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 is 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 advocating that the self-closing deflation valves, available
from almost all balloon manufacturers, be shunned as dangerous. I have
maintained for a long period of time that in terms of overall safety that
the self-closing valves are inherently superior to valves which cannot
be reclosed by the pilot while in flight. The safety of nonreclosing valves
has been very good; however, the basic reasons which caused serious accidents
with nonreclosing 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 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 1/2 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 powerlines. It is unlikely
that a pilot can do much to protect tanks from this exposure except by
avoiding powerlines.
The hazard of powerlines is generally accepted as ballooning's greatest
danger. Contacting powerlines below the equator of the envelope will generally
result in burning through the flying wires as the envelope drags the gondola
over the wires. If contact is made at or below the superstructure a good
chance of a fuel tank or fuel line rupture exists from powerline arcing.
Neither of these alternatives is acceptable. Powerline contact above the
equator is much less hazardous because the balloon will be forced to the
ground by a combination of the obstruction and wind force. Thermic conditions
may complicate the last option.
Obviously the best way to promote your personal safety (including passengers)
is to avoid powerlines. Avoidance of powerlines, while highly desirable,
will not always be possible. Each of us will at some time in our balloon
flying career make a serious inflight decision about powerline contact.
This decision will be hard, perhaps terrifying and very serious.
Knowing that collision with a powerline 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 problem is predicting absolutely that you can
clear the powerlines. On the other hand, ripping is a safer decision because
there is almost no chance that the envelope will contact the powerline
incorrectly, i.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 ripping:
a. The pilot's ego may be severely wounded because there is the possibility
of criticism for over reacting. On the other hand, it may be nice to be
alive and capable of personally discussing this criticism.
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 powerline collision threat
will give the pilot more confidence to make the correct decision.
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 extensive 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 sundown.
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 during a landing in a new subdivision and became entangled in some
wires that fortunately were not alive with electricity. There were no damages
or injuries. A balloonist and his passenger were not so lucky in Wichita
last month. They were killed when their superpressurized balloon broke
its tether and sailed off into powerlines. When a long electrical 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 these powerline accidents has its own set of circumstances and
causes for happening. Regardless, each deals a severe blow to the safety
record of the entire ballooning 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 contacts powerlines at the basket,
it is possible that the occupants touching 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. Contact 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 launching, 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 10 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 current
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 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 to 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 development 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, 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 hall generates lightning.
Here in the U.S., winds gusting to 60 and 70 mph are often 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 complex. It is difficult
to forecast and communicate 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 southwestern sky followed
by distant thunder and lightning, as well as 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 surface
and then spreads out away from the column 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 lot 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.
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 transferred 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 conditions, 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 thermal 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 flattening 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 months, 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.
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