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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

Updated NWCG Guide for Wildland Fire Modules, PMS 431

Date: May 14, 2025
Questions?  Please contact:
Fire Use Subcommittee

The updated NWCG Guide for Wildland Fire Modules, PMS 431 serves as a supplemental resource for wildland fire module operations, providing information frequently used in the field.

PMS 431 defines the organizational structure, staffing, and qualifications for Type 1 and Type 2 Wildland Fire Modules, outlining their roles in wildland fire suppression, prescribed fire, and resource management. The NWCG Guide for Wildland Fire Modules, PMS 431, should be used in conjunction with the NWCG Standards for Wildland Fire Module Operations, PMS 430.

References:

NWCG Guide for Wildland Fire Modules, PMS 431

NWCG Standards for Wildland Fire Module Operations, PMS 430

Updated NWCG Standards for Wildland Fire Resource Typing, PMS 200 Now Includes Off-Highway Vehicle Typing Standards

Date: May 13, 2025
Questions?  Please contact:
Mobile Fire Equipment Subcommittee 

The NWCG Standards for Wildland Fire Resource Typing, PMS 200 has been updated to include newly developed Off-Highway Vehicle (OHV) typing standards. These standards organize OHV information into logical categories and outline key safety requirements for occupants.

NWCG Standards for Wildland Fire Resource Typing, PMS 200 establishes minimum typing standards for aircraft, crews, and equipment used in national mobilization to wildland fire incidents. Typing designations are assigned based on measurable capability and performance criteria.

References:

NWCG Standards for Wildland Fire Resource Typing, PMS 200

NEW! S-204, Interpersonal and Critical Thinking Skills for Safety Officers Now Available

Date: May 12, 2025
Questions?  Please contact:
Risk Management Committee

The S-204, Interpersonal and Critical Thinking Skills for Safety Officers self-directed online course is now available! Developed through the Incident Performance and Training Modernization (IPTM) effort, this training supports individuals working towards Safety Officer, Field (SOFF) incident qualifications.

S-204, Interpersonal and Critical Thinking Skills for Safety Officers focuses on facilitating hazard mitigation conversations and building trust to influence safety-related decisions. Individuals can self-enroll through the Wildland Fire Learning Portal (WFLP).

Any changes to qualification pathways will take effect with the next update of the NWCG Standards for Wildland Fire Position Qualifications, PMS 310-1.

References:

S-204, Interpersonal and Critical Thinking Skills for Safety Officers 

NWCG Safety Officer, Field (SOFF) Position Page

Wildland Fire Learning Portal

Great Basin Cache Upgrading to New Inventory System

Date: May 7, 2025
Questions?  Please contact:
Great Basin Cache
Phone: (208) 387-5104
Fax: (208) 387-5573

The Great Basin Cache (GBK) is transitioning to a new inventory system to better serve the wildland fire community. During this upgrade, GBK will be unable to process standard orders from Part 1: Fire Supplies and Equipment and Part 2: Publications between May 8-20, 2025, with exceptions made for emergency fire orders. Orders will be accepted through close of business May 7.

To browse the latest available items, please refer to the National Fire Equipment System (NFES) catalogs. 

References:

NWCG NFES Catalog-Part 1: Fire Supplies and Equipment, PMS 449-1

NWCG NFES Catalog-Part 2: Publications, PMS 449-2