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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.

NWCG Latest Announcements

RMC Safety Bulletin 26-001: Rhabdomyolysis in Wildland Firefighters

Date:  May 28, 2026
Questions? 
Please contact: Risk Management Committee

The Risk Management Committee (RMC) has issued Safety Bulletin 26-001: Rhabdomyolysis in Wildland Firefighters. Research from 2016 to 2025 shows that 88 cases of rhabdomyolysis (rhabdo) were reported. Analysis of reports from eSafety, the Safety Management Information System (SMIS), and the Wildland Fire Lessons Learned Center (LLC) indicates that rhabdo is common during this time of year due to Work Capacity Tests and contributing factors such as weather, hydration, nutrition, and medication or supplement use.

RMC issued this safety bulletin to raise awareness in the Wildland Fire Community, and to provide research findings and educational resources that support reducing future cases of rhabdo.

References:

NWCG Alerts

RMC Safety Bulletin 26-001: Rhabdomyolysis in Wildland Firefighters

NEW! D-110, Expanded Dispatch Recorder Course Available Now

Date:  May 15, 2026
Questions? 
Please contact: Dispatch Position and Curriculum Management Subcommittee

NWCG is pleased to announce the new D-110, Expanded Dispatch Recorder (Instructor-led) course is now available on the Wildland Fire Learning Portal (WFLP). Developed through the National Coordination System Committee, this course introduces the structure and function of expanded dispatch, the qualities of an effective dispatcher, and provides hands-on experience with the Interagency Resource Ordering Capability (IROC) system. 

The D-110, Expanded Dispatch Recorder course aligns with the competencies and duties outlined in the NWCG Incident Position Standards for Expanded Dispatch Recorder, PMS 350-59, and is designed for individuals with no prior experience who may be called upon to support dispatch operations.

References:

D-110, Expanded Dispatch Recorder (Instructor-Led)

Expanded Dispatch Recorder (EDRC), Position Page

NWCG Incident Position Standards for Expanded Dispatch Recorder, PMS 350-59

Wildland Fire Learning Portal

Leadership Committee IAP Flyer Now Available

Date:  May 8, 2026
Questions? 
Please contact: Leadership Committee

The NWCG Leadership Committee promotes and enables leadership development across the wildland fire service. The committee provides education, training opportunities, and support for leadership innovation and best practices throughout the community.

A new IAP flyer is now available on the committee website, offering an overview of the products, curriculum, and learning opportunities the Leadership Committee develops. This resource is ideal for posting in your office, sharing with new employees, or distributing through your incident management teams to engage new voices in the leadership journey and reinforce a culture of self‑reflection, development, and growth.

References:

Leadership Committee 2026 IAP Flyer

Incident Operations Subcommittee Updates the Next Generation Position Task Book for FFT1

Date:  May 7, 2026
Questions? 
Please contact: Incident Operations Subcommittee

The NWCG Incident Operations Subcommittee (IOSC) has updated the NWCG Position Task Book for Firefighter Type 1 (Squad Boss) (FFT1), PMS 311‑14. The FFT1 Position Task Book transitioned to the Next Generation (Next Gen PTB) format in June 2025 through the Incident Performance and Training Modernization effort. Since then, IOSC has received feedback from the wildland fire community regarding coding for one of the tasks. Task #13 has been updated to include the option of evaluation in a simulation.

See IOSC Memorandum 26‑01: Transition Plan for Implementation of Updates to the NWCG Position Task Book for Firefighter Type 1 (Squad Boss) (FFT1), PMS 311‑14 for more information.

References:

IOSC Memorandum 26-01: Transition Plan for Implementation of Updates to the NWCG Position Task Book for Firefighter Type 1

NWCG Firefighter Type 1 Squad Boss Position Page