Linear Measure

1 foot = 12 inches
1 foot = 0.3048 meter
1 mile = 5,280 feet
1 chain = 66 feet
1 mile = 80 chains

Area Measure               

1 acre = 10 square chains = ch²
1 acre = 43,560 square feet = ft² 
1 acre= 4,046 square meters = m²
1 square mile = 640 acres

Volume Measure          

You need to be practiced at performing unit conversions in the field. Jotting your unit cancellation table on paper, the back of an envelope, or whatever else might be available will help you be sure you are keeping the units straight. Problem solving in units that are familiar to fire staff is crucial to sound planning. Making a mistake with units can be very costly.

Precision is an indicator of how close the repeated measurements are to each other. The precision of a measurement refers to the smallest unit with which a measurement can be made.

Example 1 - Find the precision of Gabe's measured the length of hose connector: 2.1 ft, 2.2 ft, and 2.2 ft.

Step 1. Subtract the measurements from each other.
2.1 - 2.2 = -0.1

The precision of the measurement is ±0.1 feet.

Accuracy is a gauge of how close the measured value is to the true value. The accuracy of a measurement refers to the number of significant digits. See Section 1.6.

Example 1 - Gabe is measuring a length of connector hose. He measures it three times. The values he gets are 2.1 feet, 2.2 feet, and 2.2 feet. The actual value is 2.15 feet. How accurate are Gabe's three measured values?

Step 1. The accuracy of the measurements is the difference between the true value and the measured value.
2.15 - 2.1 = 0.05

The material in Chapter 9 focuses on various math and statistical terms, including accuracy, precision, average, and mean. The content includes discussions of range and standard deviation and how they related to measured values. Fire-related topics including planning and production rate are also presented.

Flame height is the average height of flames as measured vertically, up and down. It may be less than flame length if the flames are angled in the horizontal direction, backward or forward. 
 

Chapter 8 presents information related to midflame windspeeds, flame length, flame height, and other components of fire behavior. It includes techniques for estimating different fire parameters, including rate of spread, and provides charts, graphs, and worksheets to help determine such characteristics as probability of ignition and map spread distance.

Dry bulb temperature is the ambient temperature. It is measured in degrees, from a mercury thermometer with a scale of Fahrenheit or Celsius. The dry bulb temperature should be measured in an area away from direct sunlight.

Chapter 7 describes the key weather factors referenced in the field, namely temperature and relative humidity. The chapter content includes information on dry bulb and wet bulb temperatures, dew point, and using a psychrometric table to determine the moisture content of the air.

A bearing provides a direction given as the primary compass direction (north or south), degree of angle, and an east or west designation. A bearing describes a line as heading north or south, and deflected some number of degrees toward the east or west. A bearing, therefore, will always have an angle less than 90°.

Example 1 - Megan starts at a point and goes in the direction shown in the figure below. What is her bearing?

Megan is in the NE quadrant. The primary compass direction is north. Count the degrees down from North, for a total of 70°.