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Firefighter Math: 6.9 Resection

Resection is a method of finding one's own location on a map by sighting two known landmarks.
The procedure is as follows:

  1. Find at least two landmarks on the map that can be also identified on the ground. With a compass measure an azimuth to each of the landmarks on the ground.
  2. Adjust for declination.
  3. Convert to back azimuths.
  4. Using the two known landmarks on the map, draw the lines of the back azimuths until the lines cross.
  5. The location is where the two lines cross.

 

Example 1 - Mario is in the woods and is unsure of his current location. He sees two peaks in the distance and locates them on his map. He takes the azimuth reading of the first peak and gets 327°
. He takes a reading for the second peak and gets an azimuth reading of 83°. The declination for the area is 17°W. Find Mario's location on the map below.

Step 1. Convert the magnetic azimuths to true azimuths (see Section 6.5). 
327° - 17° = 310° 
83° - 17° = 66°

Step 2. Convert to back azimuths.
310° - 180°= 130°
66° + 180°= 246°

Step 3. From the two known landmarks on the map, draw the lines of the back azimuths until the lines intersect.

Azimuths of lines

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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.

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

NWCG Firefighter Type 1 Squad Boss Position Page 

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NWCG is pleased to announce that the new S‑212, Intermediate Faller (Online), course is now available on the Wildland Fire Learning Portal (WFLP). This second course in the series provides students with the knowledge and skills required to perform the duties of an Intermediate Faller (FAL2), as described in the FAL2 Incident Position Description. This course is intended for individuals seeking to advance from Basic Faller (FAL3) to FAL2.

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NWCG Aircraft Flight Schedule Form, PMS 249