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Surface Fire: Vectoring Fire Behavior

Projecting fire spread with cross slope winds utilizes a vectoring process, where the effect of wind and the effect of slope on Rate of Spread (ROS) may be represented by separate vectors that represent both a magnitude and a direction. The resultant vector represents both a direction and magnitude of maximum spread in that direction.

  1. Slope Vector is drawn directly upslope and estimated by calculating ROS with the estimated slope steepness and Zero (0) windspeed for inputs.
  2. Wind Vector is drawn in the direction of the wind and estimated by calculating ROS with the estimated windspeed and Zero (0) slope.
  3. Maximum Spread Vector can be drawn as shown and measured to determine the resultant ROS and spread direction.
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Vectoring Wind and Slope Example - Examples of vector addition to combine the influences of wind and slope on the resulting speed and direction of fire spread.

In example A here, wind is crossing more upslope, resulting in an enhanced maximum ROS.

In example B, wind is crossing more downslope, resulting in a reduced maximum ROS.

With winds blowing downslope (±30°), the difference between the spread rates is the resulting ROS using the direction from the larger vector.

If the vectoring process is completed manually:

  • ROS is determined from the measured maximum spread vector (spread distance) and the time period used to obtain wind and slope vector estimates.
  • Heat Per Unit Area (H/A) is the same for all component vectors.
  • Fireline intensity (FLI) and flame length (FL) can be calculated from ROS and Heat Per Unit Area (HPA) using these calculations.

FLI = (ROS * HPA)/55

FL = .45 * FLI.46

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The Incident Position Standards and Next Generation Position Task Book are now available for Status/Check-In Recorder (SCKN)

Date: August 27, 2024
Contact: Incident Planning Subcommittee 

NWCG is excited to announce that the NWCG Incident Position Standards for Status/Check-In Recorder, PMS 350-32, NWCG Position Task Book for Status/Check-In Recorder (SCKN), PMS 311-32, and Checking In Resources Customer Service Job Aid, J-111 are now available.

The Performance Support Package, which for SCKN includes the Incident Position Standards, Next Generation Position Task Book, and job aid 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 Status/Check-In Recorder Position Page

NWCG Incident Position Standards for Status/Check-In Recorder, PMS 350-32

NWCG Position Task Book for Status/Check-In Recorder (SCKN), PMS 311-32

Checking In Resources Customer Service Job Aid, J-111

The Next Generation Position Task Book and Incident Position Standards are now available for Safety Officer, Field (SOFF)

Date: July 26, 2024
Contact: Risk Management Committee 

NWCG is excited to announce that the NWCG Incident Position Standards for Safety Officer, Field, PMS 350-81 and NWCG Position Task Book for Safety Officer, Field (SOFF), PMS 311-81 are now available.

The Safety Officer, Field (SOFF) is responsible for monitoring operations on an incident from a risk management perspective to provide for the welfare of incident resources and the public. The new Incident Position Standards and Next Generation Position Task Book are developed through the Incident Performance and Training Modernization (IPTM) effort.

References:

NWCG Safety Officer, Field (SOFF) Position

NWCG Incident Position Standards for Safety Officer, Field, PMS 350-81

NWCG Position Task Book for Safety Officer, Field (SOFF), PMS 311-81

Updated NWCG Standards for Electronic Documentation (eDoc), PMS 277

Date: July 25, 2024
Contact: Incident Planning Subcommittee 

The Incident Planning Subcommittee has updated the NWCG Standards for Electronic Documentation (eDoc), PMS 277.

The NWCG Standards for Electronic Documentation (eDoc) establishes the standards for collection and retention of records on wildland fires. This July 2024 update will provide incident management teams the most current standards required to maintain incident records and submit them to host units at the close of an incident.

References:

NWCG Standards for Electronic Documentation (eDoc), PMS 277

eDoc Box Directory (zip file)

NWCG Off-Highway Vehicle Typing Standard Request for Comment

Date: July 24, 2024
Contact: Mobile Fire Equipment Subcommittee 

The Mobile Fire Equipment Subcommittee has released Equipment Bulletin 24-002 NWCG Off-Highway Vehicle (OHV) Typing Standard - Request for Comment. This bulletin outlines the proposed NWCG OHV typing standard, as well as the business need for establishing the standard. Comments on the proposed standard will be accepted through August 15th using the comment form linked below.

References:

ETC-EB-2024-02: NWCG Off-Highway Vehicle (OHV) Typing Standard - Request for Comment

NWCG Off-Highway Vehicle (OHV) Typing Standard Comment Form