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8.7 Slope Effect on ROS

When fire moves upslope, the fuel ahead of the flame front is closer to the flame than if the slope were flatter.  This set-up "preheats" the fuels. The effects of slope on fire spread become greater as the slope increases. 

graphic showing slope effects on fire

APPROXIMATING THE ROS

An easy guide for approximately the ROS due to changes in slope is as follows:
1. The first tripling of slope roughly increases the rate of fire spread by a factor of 2. 
2. The second tripling of slope increases the rate of spread by a factor of 4 to 6, depending on fuel conditions. 

The effect of an increase in slope on ROS depends both on the absolute slope as well as on the midflame wind speed. See Section 8.2 for more information on midflame and "effective" wind speeds.

Example 1 - An area of shrubs is burning at a ROS of 4 chains per hour at an 8 percent slope. The slope increases to 24 percent. What will the ROS be? 

Step 1. How much did the slope change? The slope percent increased from 8 percent to 24 percent. This change represents an increase of three times the original slope.

Step 2. How much will this slope change affect the ROS? As stated above, a tripling of slope increases the ROS by a factor of 2. 
2 × 4 chains/hr = 8 chains/hr
 

4 chains/hr × 2 = 8 ch/hr

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EMC Memo 25-001: Interim Rapid Extraction Module (REMS) Training and Qualification Requirements

Date: June 3, 2025
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The Emergency Medical Committee has issued interim guidance for Rapid Extraction Module Support (REMS) teams. Until further notice, Type I and II REMS teams must designate a team leader qualified at Firefighter Type 1 Squad Boss (FFT1) or higher. This temporary change replaces the Single Resource Boss (SRB) requirement, which is currently not feasible due to administrative barriers.

This memorandum does not include any other changes to the NWCG Standards for Rapid Extraction Module Support, PMS 552. This interim change takes effect immediately and will remain in place until further notice.

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Date: June 2, 2025
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The Equipment Technology Committee issued Equipment Bulletin: 25-002 to address a manufacturing nonconformity affecting Forest Service specification, 6170-4K Chain Saw Chaps. The issue applies to chaps manufactured in 2024 and 2025 and distributed through FedMall. These chaps may have incorrectly bound edges that expose inner protective layers.

Independent purchasers should inspect all chain saw chaps received from FedMall beginning in 2024, prior to use. Review the full Equipment Bulletin: 25-002 for inspection criteria and recommended actions.

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2024 Wildland Fire Emergency Medical Service Awards

Date: May 22, 2025
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The NWCG Emergency Medical Committee (EMC) is proud to announce the recipients of the 2024 Wildland Fire Emergency Medical Service Awards. Each year, EMC recognizes individuals and groups who have demonstrated exceptional actions or accomplishments that go above and beyond their normal mission or job duties.

Congratulations to all the awardees and nominees. Through leadership and initiative, they have made significant contributions to the safety and well-being of the wildland fire community. These honors are well deserved.

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NWCG Welcomes the Incident Management Teams Association as an Associate Member

Date: May 21, 2025
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The NWCG Executive Board is honored to announce that the Incident Management Teams Association (IMTA) has joined the National Wildfire Coordinating Group as an associate member.

IMTA is a dedicated group of incident management professionals committed to enhancing the profession by promoting standards and fostering collaboration across federal, state, local, Tribal, and private sector partners throughout all phases of incident management.

“Joining NWCG aligns with our mission to elevate incident management professionals nationwide,” said Dr. Randal Collins, President of IMTA. “This is a proud moment for all of us committed to advancing public safety.”

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