- Fallout
- See Radioactive fallout.
- Faraday bag or box
- A wrapping that protects spare electronic devices against an electromagnetic pulse: the device goes inside an insulator (plastic or cloth) and then in several layers of conductive material, such as aluminum foil. See ch. 19.
- FEMA
- Federal Emergency Management Agency. It coordinates the federal response, flood insurance (NFIP), and aid to disaster survivors. Its preparedness website is Ready.gov. See chs. 1 and 23.
- Ferro rod
- A rod that throws very hot sparks when scraped, even when wet. One of the three ways of starting a fire that are worth carrying. See ch. 4.
- FIFO (first in, first out)
- "First in, first out": use the oldest items first and put the new ones in back. That way you rotate the pantry without anything expiring. See chs. 2 and 22.
- Fire triangle
- The three things a fire needs: heat, oxygen, and fuel. Remove one and the fire goes out. See ch. 4.
- Flash flood
- A rapid rise of water within minutes or hours, caused by intense rain. It is one of the most common and deadly hazards in the U.S. Get to high ground and never cross moving water. See ch. 10.
- Flash Flood Alley
- A region of steep terrain and thin soils where heavy rain fills creeks and gullies in minutes. Several areas of the U.S. have this risk, and some record the most dangerous flash floods in the country. See chs. 1 and 10.
- FM 21-76
- The classic U.S. Army survival manual, now updated as ATP 3-50.21. The source of many techniques in this guide. See ch. 1.
- Frostbite
- Injury to the skin and tissues from freezing. Do not rub, and do not warm with a fire, stove, or heating pad. See chs. 7 and 14.
- FRS (Family Radio Service)
- Inexpensive two-way radios that require no license. Short range: useful within a complex or between cars in a convoy. See ch. 19.
