The physical characteristics of the indicators that show the direction of fire spread, i.e., advancing, backing, or lateral.

A fixed location(s) used in correlation with field measurements to document spatial relationships between items of interest at the scene.

Preliminary phase of combustion in which fuel elements ahead of the fire are heated, causing fuels to dry. Heat induces decomposition of some components of the wood, causing release of combustible organic gases and vapors.

A collapsible bucket slung below a helicopter. Used to dip water from a variety of sources for fire suppression.

Airspace of defined dimensions within which air traffic control service is provided to IFR (Instrument Flight Rules) and VFR (Visual Flight Rules) flights in accordance with the airspace classification.

Weather conditions below the minimum for flight under Visual Flight Rules and therefore requiring the observance of instruments inside the aircraft for controlling flight; generally considered to be less than 1000' AGL and 3 miles distant.

Basic weather conditions prescribed for flight under Visual Flight Rules: ceiling above 1,000 feet (300 m) and flight visibility in excess of 3 miles (5 km).

A system of organizing workers to build fireline in which they advance without changing relative positions in line.

Saving a life from fire or accident; removing a victim from an untenable or unhealthy atmosphere.

A layer of air having a temperature change (lapse rate) of less than dry adiabatic (approximately -5.4 degrees F per 1,000 feet) thereby retarding either upward or downward mixing of smoke.