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Firefighter Math: 8.6 Head, Flank, and Rear Fire Terms

Each side of the fire is described in terms of head, flank, and rear. The head is the fastest spreading part of a fire's perimeter. The head is usually the side toward which the wind is blowing, and will also often be the upslope side of a fire. The head of the fire is of primary interest. 

The right and left flanks describe the sides of the fire. Flanks are perpendicular to the head of the fire. 

The rear of the fire is the side of the fire opposite the head.
 

screengrab of animation of fire spread
Click on the graphic above to view animation of fire spread along head, flank, and rear

Example 1 - Plot the perimeter and label the head, rear, and flanks of a fire with ROS of 4 chains/hour and PT of 3 hours. Assume the wind is blowing from left to right across the page.  
 

flank image

The head of the fire on your drawing should correspond to the edge of the fire's forward perimeter at the projection time. The distance from head to rear will correspond to the spread distance, in this case 12 chains.

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NWCG is excited to announce that the Quarter Two materials for the 2025/2026 Wildland Fire Leadership Campaign are now available! This annual initiative invites all leadership and wildland fire management students to engage with essential skills and knowledge needed to lead effectively in dynamic environments.

This quarter focuses on Leadership Level 2: New Leader (Conveying Intent). Conveying intent is a crucial leadership competency in the high-risk, dynamic environment of wildland firefighting. Months 4 - 6 will concentrate on how successfully conveying intent enhances situational awareness, promotes shared understanding, and empowers firefighters to exercise initiative and adapt to changing conditions.

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2025/2026 NWCG Leadership Campaign - Leadership Levels

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Opportunity to Serve the Wildland Fire Community as an IPTM SME!

Date: February 10, 2026
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NWCG is seeking experienced wildland firefighters and support personnel to serve as Subject Matter Experts (SMEs) for the Incident Performance and Training Modernization (IPTM) initiative. The intent of IPTM is to transition NWCG’s training and qualification system to a performance-based model through updated position descriptions, Incident Position Standards, Next Generation Position Task Books (Next Gen PTBs), and updates to training where needed.

NWCG is currently recruiting SMEs for the following positions:

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NEW! M-280, Resource Advisor, Fireline (Instructor-Led) Course Available Now

Date: January 29, 2026
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NWCG is pleased to announce the new M-280, Resource Advisor, Fireline (Instructor-Led) course is now available. This training supports individuals working towards Resource Advisor, Fireline (REAF) incident qualifications.

M-280, Resource Advisor, Fireline (Instructor-Led) training prepares students to serve as a Resource Advisor, Fireline (REAF) as defined in NWCG Incident Position Standards for Resource Advisor, Fireline, PMS 350-112. This course presents scenarios that reflect the diverse challenges a REAF may encounter during an incident. Through these scenarios, participants gain hands-on experience and an understanding of REAF responsibilities in a controlled learning environment.

References:

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2026 Updates to the NWCG Standards for Wildland Fire Position Qualifications, PMS 310-1

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The Incident and Position Standards Committee has updated the NWCG Standards for Wildland Fire Position Qualifications, PMS 310-1.

These updates address changes to incident position names and requirements for qualification, training, and experience. Updates related to the implementation of Complex Incident Management (CIM) and Incident Performance Training Modernization (IPTM) are also included.

The NWCG Wildland Fire Position Qualification Flowchart, PMS 308 has also been updated to reflect the recent changes.

References:

NWCG Standards for Wildland Fire Position Qualifications, PMS 310-1

NWCG Wildland Fire Position Qualification Flowchart, PMS 308

IPSC Memo 26-01: January 2026 Updates to the NWCG Standards for Wildland Fire Positions Qualifications, PMS 310-1