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As many as possible; film is cheap - the subject is perishable
Other sources of photos
• Police, fire, EMS
• Witnesses
• News media
Follow-up photography
• Removal of the aircraft wreckage
• Relocation after the wreckage is clear
• Tear-down analysis
• Autopsy
Other information
When taking photographs, include a form of label next
to the object you are photographing. It may be difficult
identifying certain parts in the photograph when reviewing
the photos at a later time.
Videography
Video recordings are becoming increasingly popular as
they often show a dynamic process.
Advantages:
• On-going narrative
• Can illustrate a process
• Record of investigation
• Real-time illustration
• Results good for training aid
• Easily edited
Aircraft Accident Investigation 14
Aircraft Accident Investigation 15
Disadvantages:
• More “stuff” to carry and keep track of
• Not as good as static scenes
• Lesser quality of image for most “truly” portable
camcorders
FIRE INVESTIGATION
Definitions
Fire
This is a collective term for an oxidation reaction producing
heat and light. There are several types of fire.
Diffusion Flame / Open Flame
A rapid oxidation reaction with the production of heat
and light. A gas flame or a candle flame is termed an
open flame – so is the burning of residual fuel following
the initial “fire ball” during an aircraft impact.
Deflagration
Subsonic gaseous combustion resulting in intense heat
and light and (possibly) a low-level shock wave. Most
aircraft impact “fire balls” are technically deflagration.
Detonation
A supersonic combustion process occurring in a confined
or open space characterized by a shock wave preceding
the flame front.
Explosion
Detonation within a confined space resulting in rapid
build-up of pressure and rupture of the containing vessel.
Explosions may be further categorized as mechanical
or chemical. A mechanical explosion involves the
rupture of the confining vessel due to a combination of
internal overpressure and loss of vessel integrity. A
chemical explosion involves a chemical reaction resulting
in catastrophic overpressure and subsequent vessel
rupture.
Auto-Ignition Temperature
It is the temperature at which a material will ignite on
its own without any outside source of ignition.
Flammability Limits
These are generally listed as the upper and lower flammability
or explosive limits. These describe the highest
and lowest concentrations of a fuel /air by volume percent
which will sustain combustion. In other words, a
fuel air mixture below the lower limit is too lean to burn
while a mixture above the upper limit is too rich to
burn. In considering in-flight fires, the upper and lower
limits may be useful as they vary with temperature and
altitude. Thus, for an in-flight fire to occur, the aircraft
must be operating in a temperature / altitude regime
where a combustible fuel-air mixture can exists
Flashover
This term is used to describe the situation where an area
or its contents is heated to above its auto-ignition temperature,
but does not ignite due to a shortage of oxygen.
When the area is ventilated (oxygen added) the
area and its contents ignite simultaneously, sometimes
with explosive force.
Flashpoint
This is the lowest temperature at which a material will
produce a flammable vapor. It is a measure of the volatility
of the material.
What is a fire?
Elements of a fire
• Combustible Material
• Oxidizer (Usually ordinary air – 20% Oxygen – is
sufficient)
• Ignition: in order for a fire to ignite, the ignition
source must first raise the temperature of the combustible
material (or vapors) in its immediate vicinity
to the ignition temperature of the material.
• Heat or energy to sustain the reaction.
Fire Classes
• Class A
• Class B
• Class C
• Class D
Significance of Fire
Pre-impact fires in the aircraft are relatively rare, but
when they occur, the results are often catastrophic.
They can be causal to the accident.
Post-impact fires are much more common. From an
investigation standpoint, they are resultant from the
original accident sequence. Post-impact fires are the
main threat to accident survivability.
Fire scenarios in aviation
Basic Questions:
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