You must have grown up in the east, as the term, even nationwide, is "wildland fire" not "woodland fire," a term 6-10 eastern state residents have used in conversations with me. I'm a graduate forester by education and the term woodland is not used in the profession much anymore. In any case it is wildland fire in the west, where the worst and largest wildland fires burn. The exception seems to be Florida where the wildland-urban interface burns with some regularity and the incredible fire in the Gatlinburg area some years ago. The largest National Wildlife Refuges in the east can have some very large fires as well. When I use the term east, I'm referring to the midwest, south and northeast, as in my perspective, if it's east of Montana, Wyoming, Colorado and New Mexico it is all east.
Frequencies for wildland fire are mostly fixed and do not change very often. The National Interagency Fire Center (NIFC) system has had very few changes since the late 1970's and early 1980's. The tactical frequencies have been around since the 1970's. Originally the USFS had 3 and the BLM had 3. The BLM had some command frequency pairs and the USFS had some. In the 1990's or late 1980's the 2 systems were combined into 1. The commands did not meet the 2019 new allocation of the fed's 162-174 band. They just flipped the inputs and outputs to comply, although some of the inputs are not in the repeater input allocation. They probably got a waiver as all of the command frequencies had a nationwide, exclusive use authorization. The formal name of this system is the National Incident Radio Support Cache because it can be used for other types of disasters and large, non emergency incidents. It has been used at some political party conventions, for example.
The National Interoperability Field Operations Guide (NIFOG) frequencies are being used more often as the years pass. Commands 8-12 in the NIFC system are actually NIFOG frequencies. Local agencies use the VFire and VTac frequencies a lot. The feds have them in their radios as they often work mutual aid on local jurisdictions.
The 2 federal government nationwide, all agency itinerant, assignments of 163.1000 and 168.3500 have been around for a very long time and are still used. These are usually labeled on this website and in some official agency directories as "common" frequencies. An additional 4 of these were picked up in 2005 when narrowbanding expanded the number of frequencies from 40 per 1 MHz to 80 per 1 MHz. The National Natural Resource Air Guard of 168.6250 was in place when I was on my first wildland fire in 1973 and I don't know how long it had been in place prior to that. It used to have a very little used repeater capability, which all agencies dropped 30-35 years ago. The input became the USFS National Law Enforcement Tactical frequency. 168.6500 is now National Flight Following, I think it or another frequency was originally the BLM Air Guard. Another that had a long term nationwide clearance was 168.5500. NIFC has now designated as the nationwide smokejumper and helicopter rappel air to ground frequency with each of those having its own PL tone. They also designated 168.3500 with the same PL as the nationwide smokejumper ground tactical. As soon as an incident is assigned a tactical frequency, the smokejumpers use it, so this smokejumper tactical is only used for a short period of time. Some remote fires are staffed by smokejumpers exclusively for the entire length of the fire and the tactical remains the same. All geographic areas, with the exception of the Pacific Northwest have USFS region and BLM state office tactical frequencies (1-3 of them) assigned. Utah and New Mexico have 7 or 8 as the federal agencies have pooled everything they have into one tactical channel system. The Eastern and Southern Geographic Area Coordination Centers (GACC's) have a single tactical assigned. A system of nationwide air to ground frequencies has been established with common frequency designators. There are about 60-70 of those.
National Forests, National Parks, BLM public lands, National Wildlife Refuges and the Bureau of Indian Affairs have used the same frequencies since the federal VHF High band was put in place in the 1950's. Sure there were numerous modifications in that time frame, but some units I know of used the same frequencies since the 1960's and have only been changing those in the last 20 years. The big change and what is driving much of our discussions over frequency assignments in the last 5-10 years, is the 2019 National Telecommunications and Information Administration (NTIA) directive that reallocated the 162-174 band into specific blocks for repeater inputs (162-166.4875), simplex (166.5000-169.4875) and repeater outputs (169.5000-173.9875). The federal UHF band, 406-420) band was reallocated around the time of the 2005 narrowband directive for federal agencies. On wildland fires UHF is only used for repeater linking, remote base control and incident camp nets. Some other federal agencies use this band for their primary on the ground activities. Once the reallocation changes have been made to comply with the 2019 directive you won't see as much change in the future.
The VHF-AM frequencies can change from time to time because the FAA is in charge of those, not the , which takes the FCC role in federal government communications regulation. The FAA tries to keep the same assignments from year to year, but has other issues that don't always make that possible. The air attack base frequency of 123.975 has been around for a very long time, but in the last 10-15 years some bases and sometimes all the bases in a state have been changed to other frequencies. These frequency assignments appear to be permanent in the last 5-10 years. The FAA gives NIFC some AM air to air frequencies each year to use on incidents, but these are subject to annual changes also.
NIFC has 5 nationwide frequencies for Air to Air Tactics (FM) and Air to Ground use on nationally managed incidents, i.e. those using Type I and Type II Incident Management Teams (IMT's). There is a delay to get an Air Tactics (AM) frequency for incidents from the FAA, but has these to be able to put them in use immediately. This also gives them the option to use them for air to ground use also, if one of the national air to ground frequencies can't be used. This is not common as air to ground assignments from the national list can be used on incidents when not assigned to the local area.
There are other frequencies used on large, nationally managed incidents that will change, not only annually, but sometimes for each nationally managed incident in the same area. When all of the other above frequencies have been exhausted due to multiple incidents occurring in the same area, NIFC has special authorization to use FM frequencies authorized for all federal agencies that they are not using at the time of the incident. This authorization is not delegated below the NIFC level. These are the mystery frequencies on incidents and they are primarily used for the command repeaters and are sometimes difficult for hobbyists to determine. They can be used for air to ground in some cases. Rarely are they used for tacticals as simplex use does not carry long distances. Sometimes these are used for many years, even with the same command frequency identifier, but this is up to chance. A federal agency may change or expand one of its systems at any time, so new frequencies are popping up all the time. Some people have access to the communications plan developed for each incident and post those frequencies on RR threads. Sometimes we have to do some searches and hopefully someone that does posts what they have found.
The last paragraph is the only time your statement "there are very few fixed frequency assignment there, it changes every season and every fire" is completely valid. In fact, for a lot of large, nationally managed fires, fixed frequency assignments are those used most often. NIFC prefers to use their system before assigning other frequencies. For the initial attack period of fires and those that are managed with locally organized Type III IMT's use local nets. These teams use locally assigned nets. Some national forests have set up fire nets, such as the Tonto NF, which has 2 of them. In California nearly every NF has a "Service Net," which can be used as a command for Type III incidents.
I have access to a few sources where I can get official frequency use information. Some of it comes from official guides and some sources are human. I try to share this information as much as possible. I sometimes have trouble with database administrators in having those frequencies listed correctly. Many federal pages on the database and the NIFC system page on the "Nationwide Frequencies" section of the database need work. I'm getting older and slower so I'm not caught up with the submissions I need to make. I also worked for the U.S. Forest Service during my primary career in 4 western states. I was assigned to 108 fires and was an investigator for claims and employee misconduct. I was sent to many other national forests as an investigator. The fires were on USFS, NPS, BLM, BIA state and local jurisdictions. Some fires were very small and only involved myself and 1-3 hours and some were huge such as Yellowstone in 1988 for 5 weeks. Most of these were on the line assignments and others for command post assignments. I had access to and used the incident comm plan on all of them.
Lastly I like your comment about technology becoming more complex and harder for us. One thing I can't keep up with is all the abbreviations and monikors. They are used everywhere and have become very prevalent on the internet. So maybe you will understand that your statement of " but the added issue of things like OTAP and FPP of radios makes things change quickly" is Greek to me. I try to spell out all abbreviations when I use them in posts. I learned that this is a requirement for all scientific and technical writing. It isn't just something I learned in high school and college long ago, 1970 or 1971 if memory serves me, but is a current requirement as well. I have a huge issue with the number of undefined abbreviations shown on the database. We all need to understand what we are hearing, not just that we are hearing it.
