In the aftermath of the ValuJet 592 tragedy, carriage of hazardous materials — HAZMAT — aboard airliners has received a great deal of attention. But what about other operations? When you preflight your aircraft, do you consider what you and your passengers are bringing, along with the weight? AVweb's Kim Broadwell examines current regulations as well as several recent HAZMAT incidents aboard aircraft large and small.
May 31, 2000
|About the Author ...
Kim Broadwell is a
physician and commercial pilot who has combined both worlds as a specialist in
aerospace medicine. He has had several incarnations, including small town doc,
flight surgeon for NASA at the Johnson Space Center, and director of the medical
clinic at Logan International Airport. He should be an astronaut, but his eyes
are too weak and he couldn't get the rules changed while he worked at NASA.
Along the way, he has served as an Army Flight Surgeon, and as a faculty member
at Duke University and the University of Rochester.
An FAA Aviation Medical
Examiner since 1980, his medical practice is devoted exclusively to FAA flight
physicals and consultations about difficult medical certification issues. He and
his aviation-oriented, ex-NASA wife live in Rochester, NY. They live with their
son, an E-90 King Air mushing along in the charter business, and an A-36 Bonanza
used to visit the King Air when it's in the shop.
This image was taken by Kim's
daughter, who lives in Washington, D.C. He holds COMM-SMEL-Instrument ratings,
but covets an ATP rating when he has enough hours.
Oxygen generators are improperly placed in a forward
cargo compartment. A fire starts, and the airplane is destroyed. No one was
killed when this happened to an American Trans Air DC-10 on the ground in
Chicago in 1986, but the lesson went unlearned. Ten years later, oxygen
generators fueled the fire that led to the ValuJet Flight 592 crash into the
Florida Everglades on May 1996, focusing national attention briefly on the
transportation of hazardous materials (HAZMAT) by air.
HAZMAT's public "infamy" may have passed until the second accident,
but in the wake of the ValuJet crash the FAA has gone on a HAZMAT inspection
crusade over the past four years. The FAA now has five times the HAZMAT staff it
did before ValuJet 592, and has collected more than $14 million in fines over
the past three years. Although the FAA's crackdown is aimed mostly at shippers
and commercial carriers, it's important to realize that the same HAZMAT rules
apply to each and every one of us while flying. It doesn't matter if the flight
is conducted under FAR Part 91, Part 135, or Part 121. The main concern for the
average Joe should not be a potential FAA fine, however — it's what can happen
if you're oblivious to your cargo. Much of the hazard comes from luggage or
cargo that is not identified or handled as "dangerous." For example,
the complete destruction of a FedEx DC-10 in 1996 by a fire that erupted in one
of its cargo containers was never entirely explained by the NTSB, but was
probably caused by flammable liquids in a lab machine that was not identified as
Air carrier accidents grab national headlines, but HAZMAT problems are not
the exclusive territory of the "big guys" of aviation. Ask the pilot
of a Cessna Skymaster whose plane caught fire while landing — his passenger had
attempted to right an overturned gasoline can, while holding a burning cigar in
his hand. In the larger scheme of general aviation accidents, problems with
hazardous materials cargo are not as significant as more familiar causes, such
as continued flight into bad weather, controlled flight into terrain, or fuel
exhaustion. On the other hand, if your cargo bites you in-flight, such
statistics become irrelevant. A prudent pilot needs to be familiar with HAZMAT
What Are The Hazards?
Common, Everyday Materials...
Like many problems in aviation, a HAZMAT disaster is often something we do to
ourselves. For those who are saying to themselves, "I'd never carry fuel in
the passenger compartment," other hazards may be lurking among those loose
items in the back of the plane. Pilot-owned aircraft tend to accumulate extra
payload with the passing of time, just as certainly as desiccated French fries
grow under the seats of the family car. Investigating the explosion of a Cessna
172 at a low altitude, the NTSB traced the probable cause to fumes from a
container of TCP. A very volatile and flammable organic solvent, TCP is a fuel
treatment that the pilot had probably hauled around for many flight hours
without a second thought.
Besides the risk of explosion, smoke or fire, a cargo of dangerous goods
(another term for HAZMAT) can potentially incapacitate the crew because of
direct toxic effects. Agricultural application pilots are well aware of these
risks, even though the loads carried in their hoppers are technically exempt
from HAZMAT regulations. Ag-pilots might be reluctant to admit it, but some of
them carry an atropine antidote when they are applying organophosphate
pesticides. They base their self-dosing on how "drooly" they are.
Organophosphate pesticides are in the same chemical family as the nerve agents
stockpiled by Iraq before the Persian Gulf War, and exposure can cause nervous
system problems in humans, as well as the intended insect targets.
...And Others Not So Common
Dry ice is an example of a more subtle risk, and the amount that may be
carried on any flight is regulated. Dry ice becomes carbon dioxide vapor, and a
build-up of this gas in a cabin can cause medical problems for both aircrew,
passengers, and in some cases, animal cargo. If someone asks you to transport
frozen steaks or other cargo likely to contain dry ice in a small aircraft, you
should get a safety "reality check" from an experienced shipper or
aeromedical professional. Theoretically, small pressurized aircraft present a
greater opportunity for CO2 accumulation than an unpressurized or larger plane,
because of less air circulation in the cabin, but dry ice can be a problem for
even airline-size planes if the load is great enough. In 1998, a DC-8 freighter
in Dallas was forced to taxi back and abort its takeoff after the entire
cockpit crew was overwhelmed by carbon dioxide buildup from a cargo of dry ice.
Infectious agents and radioactive materials are often problems for commercial
HAZMAT cargo carriers, but represent delayed risks and are unlikely to cause an
in-flight incident. These agents are more apt to cause grave concerns among
ground cargo crews, or anyone who might have been inadvertently exposed to them
at the airport. I encountered this scenario while managing the Logan Airport
medical facility in Boston, when a carton of live HIV (AIDS virus) appeared to
be leaking in transit. The box was ultimately determined to be wet only on the
outside, without any rupture of contents, but this information wasn't available
until it was unpacked at a special laboratory. General aviation pilots are
usually spared this kind of anxiety, but if your sneezing first officer with the
flu has not had the sense to ground himself, he's both an infectious disease
risk as well as a hazard to safe flight.
The government places the responsibility for not accepting
"improper" hazardous materials aboard aircraft squarely on the
shoulders of the commercial carriers and individual pilots, no matter how sneaky
or ignorant the traveling public may be. Since 1994, all airlines, airports, and
shippers have been required to display very prominent placards warning against
HAZMAT on commercial flights, threatening fines up to $25,000. All flights are
forbidden by DOT Hazardous Material Regulations (HMR, 49 CFR Part 175) from
carrying anything even remotely hazardous, although §175.10 lists many
exceptions (such as small aerosol cans and elaborately packaged wheelchair
batteries). There is even a regulation to "allow" a person to board an
aircraft after they have been injected with a tiny amount of radioactive tracer
for a medical test (like a bone scan or Thallium treadmill test!) Yes, even the
extra quart of oil you carry in your plane is probably illegal unless it is
"properly packaged and labeled."
What the HMR regulations actually demand is that any HAZMAT accepted for
transport on an aircraft meet requirements for container, labeling and quantity
that are material-specific. The FARs require each commercial operator to
structure their operations manuals to ensure everyone is trained to meet this
HMR Part 175 standard, but the details are left up to each operator.
Unfortunately, at least for the airlines, the questions passengers are asked at
the ticket counter are directed entirely toward terrorism and bombs, to the
detriment of "Do you have any lighter fluid in your bags?" Every pilot
in command should take a moment to ask the appropriate questions of passengers
boarding the aircraft. A partial list of common hazards that are frequently
reported as causing trouble, or forbidden by HMR Part 175, is shown in the table
lighters or other lighters with "flammable liquid
Any kind of lighter
Refills for butane
lead-acid batteries (often attached to an electric wheel-chair and
Large aerosol cans
(like spray paint).
cylinders, such as scuba tanks or welding equipment.
Machines or machine
parts that may contain flammable liquids (e.g., fuel left in
chainsaws, generators, and other powered equipment).
firearms or ammunition.
chemicals: solvents, bleach, cleaners, paint.
mercury-filled barometers and thermometers.
Learning From The Misfortunes Of Others
NTSB reports are valuable to pilots trying to avoid the repetition of someone
else's mistakes. These reports are limited by definition to incidents or
accidents that have met NTSB notification criteria, as set forth in NTSB
regulations (Part 830). It is also useful, in the best tradition of hangar
flying, to learn from incidents where the crew was able to avert disaster and
avoid becoming a headline. One source of such information is the Department of
Transportation's Research and Special
Projects Administration (RSPA), which compiles data on incidents involving
the transportation of hazardous materials by all modes, including air. I used
this database to obtain a broader picture of in-flight incidents or
near-disasters that were caused by hazardous materials. These reports are
admittedly slanted towards larger operations that have better mechanisms for
tracking and reporting such events. It could also be argued that they have more
incentive to report, since their size makes their activities a much bigger
target for official scrutiny. Reports made to the NASA
Aviation Safety Reporting System (ASRS) also offer insight into disasters
that could have happened.
In two years of RSPA reports, 2.5 percent of the almost 500 HAZMAT-by-air
incidents involved emergency actions by the crew, such as diversion to an
alternate destination, deployment and use of oxygen masks, expedited landings,
or aircraft evacuations. Another 3.5 percent of occurrences were close calls,
with pilots and ground crews identifying fires, smoke, or other emergencies
while taxiing, or in the immediate post-flight period. Nearly half of these
events were caused by cargo not identified as hazardous. Many examples of these
so-called "hidden shipments" were items buried wittingly or
unwittingly in passenger luggage.
The 1988 loss of an American Airlines DC-9 was caused by this kind of package
in the cargo hold. An improperly packed drum containing hydrogen peroxide and a
product for "stone washing" jeans was not declared as a hazardous
shipment, and was loaded in the cargo hold on its side. The shipment leaked,
starting a serious fire shortly before the flight landed in Nashville. All the
injuries were minor, but the plane was destroyed.
Within my study period, one clerk in Alaska did avert a potential problem by
questioning a woman about the bright orange rope she had tied around her package
for air shipment. The string she had conveniently found in her husband's tool
shed turned out to be blasting cord! This illustrates another theme running
through the HAZMAT incident reports: People in the Alaskan bush are likely to
ship anything and everything by air, including chainsaws loaded with gasoline.
One hidden shipment from Homer, Alaska, to Tucson, Ariz., contained undeclared
fireworks, gunpowder, propellants and a tank of acetylene welding gas.
Sometimes poor maintenance and bad luck will catch up with a pilot at the
same time, as in the case of an air taxi pilot whose plane caught fire while
delivering fuel at a remote landing strip. He was able to land and put out the
fire, which was being fueled by a leaking drum. A charred wire beneath the
floorboard identified the ignition source: The lower rotating beacon had been
removed in the past, but when the cockpit panel beacon switch was activated the
old wiring was still "hot."
Sources of combustion are guaranteed to be both unpredictable and
inconvenient. The ASRS recently reported incidents that prove a corollary to
Murphy's Law — if a source of combustion can light off, it will. The juggling
of luggage can produce enough friction to cause kitchen matches to ignite, which
will leave the back of your family cruiser in sad shape. One pilot of a Cessna
172 reported that a spare nine-volt battery he had packed for his headset had
shorted out across the metal of a zipper. He was fortunately able to reach the
bag and put out the fire before it got out of control. A Cessna 182 pilot
reported an explosion in his baggage compartment caused by an overheated
nine-volt alkaline battery that had shorted out on a piece of metal in his
The majority of non-incendiary HAZMAT events in the study involved leaky or
damaged containers. Some of the incidents were caused by serious chemical
toxins, such as hydrogen sulfide trapped in a shipment of oil field gear. This
was reported twice, and in one case sent seven ground crew to the hospital when
they opened the hold.
Many reported incidents in the RSPA database were caused by odors emanating
from leaky cargo packages that, in retrospect, did not represent a serious toxic
hazard to the crew. Nonetheless, pilots generally have no way to distinguish
between a smell that is merely obnoxious and an odor that represents a serious
hazard. The crew is usually compelled to take emergency action when strange
odors start wafting in from the back. The flight crew's options at that point
are limited: Increase cockpit ventilation (if possible), don oxygen masks and
smoke goggles (if available), and land as soon as practicable.
What can a careful pilot learn from the bad experiences of others? Here are a
few tips for preventing problems with hazardous materials:
Maintain a healthy paranoia about all cargo loaded on your aircraft,
including baggage contents and how they are packed. As you perform your
pre-flight weight and balance calculations, ask your passengers what they
are bringing with them, in addition to considering the weight.
Leave spare batteries in the original packaging, or use well-secured
Take the time to tie down and secure cargo. We all know this protects
against flying missiles in turbulence, but proper tie-down is also
insurance against upsetting a poorly packed hazard.
Lastly, but probably the most important: Don't ask for trouble —
carrying fuel anywhere other than the fuel tanks is a big risk. Be sure
and check any cargo (like camp stoves) that might contain residual
gasoline or other flammable liquid.
Usual Disclaimer: This article is intended as a safety advisory
for pilots, and is based on data published by the National Transportation
Safety Board, the Aviation Safety Reporting System, and the Research and
Special Programs Administration's Hazardous Material Information System. It is
not intended to judge or reach any definitive conclusions about the ability or
capacity of any person, living or dead, or any aircraft or accessory.