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Mapping: Map and Field Measurements

  1. Map Scale & Map Distance
  2. Slope Estimation
  3. Unit Conversions
  4. Average Latitude for Each State
  5. Declination

Map Scale & Map Distance

The map scale is printed in the map legend. It is given as a ratio of inches on the map corresponding to inches, feet, or miles on the ground. For example, a map scale indicating a ratio of 1: 24,000 (in/in), means that for every 1 inch on the map, 24,000 inches have been covered on the ground. Ground distances on maps are usually given in feet or miles.

Scale Rep. fraction Map (in/mi) Map (in/ch) Feet per map inch
1:253,440 253.44 0.25 0.0031 21120
1:126,720 126.72 0.50 0.0063 10560
1:63,360 63.36 1 0.0125 5280
1:62,500 62.50 1.01 0.0127 5188
1:31,680 31.68 2 0.025 2640
1:24,000 24 2.64 0.033 2000
1:21,120 21.12 3 0.0375 1760
1:15,840 15.84 4 0.05 1320
1:7,920 7.92 8 0.1 660

Firefighter Math Map Scale; Firefighter Math Spread/Map Distance

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Slope Estimation

Slope (Degrees) Slope (Percent)
10° 17.6%
20° 36.4%
30° 57.7%
40° 83.9%
45° 100%
50° 119.2%
60° 173.2%
70° 274.7%
80° 567.1%
90° ∞

Standard LANDFIRE slope themes are represented in units of degrees (°). Many locally produced landscapes over the year’s stored slopes in percent (%). It is much easier to estimate slope in percent, estimating the elevation change and the horizontal distance and calculating the ratio. BehavePlus, and BEHAVE tools before that, default to slope input in percent.

Firefighter Math Slope Percent and Slope Angle

To convert from slope in degrees (°) to slope in percent (%), a scientific calculator is needed.

  1. Enter the slope in degrees.
  2. Press the Tangent button.
  3. Multiply the result by 100 to get slope in percent.

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Unit Conversions

Online and downloadable apps are available from Apple (OSX & IOS), Google Play (Android), and MS Windows for making unit conversions for distance, temperature, area, volume, weight, time, energy and other items.

Metric Unit Multiply by English Unit Multiply by Metric Unit
Meters/min 3.28084 Ft/min 0.3048 Meters/min
Meters/min 2.982582 Ch/hr 0.33528 Meters/min
Meters/min 0.03728 Miles/hr 26.8224 Meters/min
Kg/m3 4.460897 Tons/ac 0.22417 Kg/m3
Kg/m3 0.062 lb/ft3 16.129 Kg/m3
Tonnes/ha 0.44609 Tons/ac 2.2417 Tonnes/ha
Kw/m 0.28909 BTU/ft/sec 3.4592 Kw/m
Meters 0.049709 Chains 20.117 Meters
Meters 0.3048 Feet 3.28084 Meters
Millimeters 0.0393701 Inches 25.4 Millimeters
kilometers 0.62137 miles 1.6093 kilometers
hectares 2.4711 acres 0.40469 hectares

Firefighter Math Conversions reference provides several tables and conversion factors for the user.

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Average Latitude for Each State

State Average Latitude
Alabama 33
Alaska 65
Arizona 35
Arkansas 35
California 38
Colorado 39
Connecticut 41
Delaware 39
Florida 28
Georgia 33
Hawaii 21
Idaho 45
Illinois 40
Indiana 40
Iowa 42
Kansas 39
Kentucky 37
Louisiana 31
Maine 45
Maryland 39
Massachusetts 42
Michigan 43
Minnesota 46
Mississippi 32
Missouri 39
Montana 47
Nebraska 41
Nevada 39
New Hampshire 44
New Jersey 40
New Mexico 34
New York 43
North Carolina 35
North Dakota 47
Ohio 40
Oklahoma 35
Oregon 44
Pennsylvania 41
Rhode Island 41
South Carolina 34
South Dakota 44
Tennessee 36
Texas 32
Utah 39
Vermont 44
Virginia 37
Washington 47
West Virginia 38
Wisconsin 44
Wyoming 43

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Declination

Global Reference

Calculator

US/UK World Magnetic Model - Epoch 2015.0 Main Field Declination (D)

(East Declination in Red, West in Blue; subtract from true compass reading)

Image
Recent map of magnetic declination for field navigation.

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NWCG Latest Announcements

NWCG Equipment Technology Committee Releases Safety Warning: 24-001 Stihl Chainsaw Toolless Fuel Cap Spill Prevention

Date: November 14, 2024
Contact: Equipment Technology Committee

The Equipment Technology Committee (ETC) has released Safety Warning: 24-001 Stihl Chainsaw Toolless Fuel Cap Spill Prevention. Misaligned toolless fuel caps on Stihl chainsaws have led to recurring fuel spillage, fuel ignition, and burn injuries during wildland fire management operations.

This Safety Warning is intended to highlight the details and recommended procedures for the installation of a Stihl chainsaw toolless fuel cap, as well as how to identify and correct a misaligned, damaged, or broken fuel cap to help prevent fuel spillage.

References:

NWCG Safety Warning: 24-001 Stihl Chainsaw Toolless Fuel Cap Spill Prevention

Advertencia de equipos 24-001: Prevención de derrames de la tapa de combustible sin herramientas de la motosierra Stihl

NWCG Alerts

The Incident Position Standards and Next Generation Position Task Book are now available for Equipment Time Recorder (EQTR)

Date: November 13, 2024
Contact: Incident Business Committee

NWCG is excited to announce that the NWCG Incident Position Standards for Equipment Time Recorder, PMS 350-51 and NWCG Position Task Book for Equipment Time Recorder (EQTR), PMS 311-51 are now available.

The Performance Support Package, which for EQTR, includes the Incident Position Standards and Next Generation Position Task Book were developed through the Incident Performance and Training Modernization (IPTM) effort. The Performance Support Package will support trainees, those qualified in the position, and evaluators.

References:

NWCG Equipment Time Recorder Position Page

NWCG Incident Position Standards for Equipment Time Recorder, PMS 350-51

NWCG Position Task Book for Equipment Time Recorder (EQTR), PMS 311-51

The Incident Position Standards and Next Generation Position Task Book are now available for Personnel Time Recorder (PTRC)

Date: November 13, 2024
Contact: Incident Business Committee

NWCG is excited to announce that the NWCG Incident Position Standards for Personnel Time Recorder, PMS 350-53 and NWCG Position Task Book for Personnel Time Recorder (PTRC), PMS 311-53 are now available.

The Performance Support Package, which for PTRC, includes the Incident Position Standards and Next Generation Position Task Book were developed through the Incident Performance and Training Modernization (IPTM) effort. The Performance Support Package will support trainees, those qualified in the position, and evaluators.

References:

NWCG Personnel Time Recorder Position Page

NWCG Incident Position Standards for Personnel Time Recorder, PMS 350-53

NWCG Position Task Book for Personnel Time Recorder (PTRC), PMS 311-53

NWCG Risk Management Committee Releases Safety Bulletin: 24-001 Use of Respirators on Wildland Fires

Date: November 7, 2024
Contact: Risk Management Committee

The Risk Management Committee (RMC) has released Safety Bulletin: 24-001 Use of Respirators on Wildland Fires. As wildland fire respirators are available through several established vendors, wildland fire personnel need to understand regulations and limitations of respirator use in the workplace.

Safety Bulletin 24-001 outlines the following topics regarding respirator use for wildland fires:

  • Requirements for Respirator Use
  • Voluntary Respirator Use
  • Current Respirator Options
  • Unknown Risks of Respirator Use

This bulletin also provides mitigation recommendations to help reduce smoke exposure for wildland firefighting efforts.

References:

NWCG Safety Bulletin: 24-001 Use of Respirators on Wildland Fires

NWCG Smoke Management Guide for Prescribed Fire, PMS 420-3

VIDEO: Protecting Wildfire Personnel from Smoke - How Incident Management Teams Address Smokes Risks

VIDEO: Smoke, Knowing the Risks