The map below shows the locations of 871 Low Frequency Radio Range stations that we’ve been able to identify (see Methodology below). A breakdown is as follows:
This map likely represents nearly all (greater than 95%) of the LFR stations that ever existed in North America. Note that later Visual / Aural Ranges (VAR’s) are not shown on this map, and we’ve provided a separate list for Low Power and proposed stations that never were. We are always looking for new information and updates – see below if you would like to help!
Note that these stations were not active all at once, stations came and went over time as the graph shows below as air routes were realigned or simply, better locations were found. Some cities / areas relocated their stations two or three times over the life of the system. Numerous short-term stations came and went with the needs of WW2. The peak amount of stations in-use within the Lower 48 appears to be just over 400 sometime between 1945 and 1950. One census based on 1944 Sectionals shows 404 Stations, the 1944 Army Air Force Radio Facility Charts (AAFRFC) lists 424 stations (once 34 “homing” or NDB stations are removed) including stations then under construction, “Over 400” was the figure given in the CAA 1953 Pilot Radio Handbook. The 61 US locations that had a station for 30+ years, nearly the whole lifespan of the system, are noted with an asterisk (*) when clicked below.
LFR saw less use abroad. Whereas the US and then Canada established LFR as a system of “highways” to be followed like their extensive rail and road networks, Europe, divided into smaller territories, took a more “nautical” approach and treated radio beacons akin to lighthouses that provided bearings to aviators. As such, they preferred the radio compass, and later other homegrown systems such as Lorenz, Consol, Gee & Decca. LFR could not reach across oceans, so other options were then needed. After initial experimentation with LFR, Australia preferred their own system based on Lorenz, and later on VAR’s. Soviet states did not use LFR at all. The war would expand the use of LFR worldwide, but many militaries would use ground-based Radio Direction-Finding (RDF) stations for sparsely populated regions, where voice guidance could be given to pilots by pinpointing their radio signal with no need for onboard navigation equipment or other ground infrastructure. All of these systems ultimately gave way to the VOR which became the international standard during the 60’s and 70’s and the first radio navigation system many countries implemented.
Disclaimer: any information shown on this map is subject to additional updates/corrections. Please reach out to us below if you have any comments / additions) and of course, use none of this data for real world navigation.
Click on each station to uncover additional information, including geographic coordinates and, if we can determine it from the information on hand, the last station type that was used (many early loop stations were later upgraded to Adcock types) and approximate lifespan as seen on sectionals - special thanks to Tom Johnson for this information. Stations changed Morse code identifiers and frequencies over the years, but we do provide the identifier as listed in the August 1944 AAFRFC or other noted year. Beam alignments also frequently changed as the airways evolved and they would have been a herculean effort to catalogue. If one needs to study the specifics of station’s history in detail, we’d advise diving into the sectionals and other information on the Resources page. One tip: LFR courses shown on the charts were almost always given in local magnetic headings, and will need to be corrected to the magnetic declination of the era, as the magnetic poles have indeed shifted over the decades. Using current and historic aerial imagery, topo maps, old approach plates and other sources, our team worked to geo-locate stations to the nearest arc second or better, and checked to see what might be left at each location as of late 2020/early 2021. The locations are color coded as follows:
Yellow - Review Pending (15 or 1.7%): Historic aerials / maps have yet to reviewed by our team. This data is either raw coordinates from the AAFRFC which has varying accuracy as described below or has been roughly located with +/- 1 mile accuracy from an available map or other source.
Green – Confirmed (332 or 38.1%): The location and status was confirmed and something remains of the station today (or at least in the most recent imagery), zoom in close and you can see for yourself. The odds of this are better in the west and the northern reaches of Alaska and Canada due to more open space. The markers are spot on (+/- 10’ accuracy) and this classification is broken in three tiers as follow:
Grey - Confirmed: No Trace (321 or 36.9%): The station location was positively identified by an historic aerial or topo map; however, it is clear nothing remains of the station today – generally due to redevelopment of the site. This is especially common in urban areas and densely populated regions such as the Northeast. Locations identified by an aerial are also +/- 10’ accuracy, by USGS or other similar topo map closer to +/- 50 feet (<1 arc second).
Orange - More Review Needed (203 or 23.3%): The team's attempt to identify the precise location / status of a station was not successful. This is normally due to the lack of aerial photos and maps before 1970’s in certain areas by which point many stations were already gone, or the aerials from the time the station existed had low resolution or significant ground clutter making it tough to make out the station. Many transient wartime stations were set up and dismantled in the years between aerials surveys making them difficult to find. Although we know that the station existed based on the AAFRFC, sectional or other source, we simply don’t have the information to precisely pin on a map or say for certain what may be left of it today. Sometimes a possible candidate may be marked but needs further verification. That said, these locations were checked against sectional maps and the accuracy of has been refined to be within a quarter to half mile of the station’s probable location.
We’d love your help pinning all these stations down, especially the “More Review Needed” and “Review Pending” categories. Do you know something more about any station on this site? Perhaps we totally missed a location? Do we have a “confirmed” location wrong? If so please fill out the Google Docs Survey below with any coordinates, notes, photos, etc. We are happy to continue adding to this database!
Please note that nearly all of these sites are located on private land or public land where access is restricted. Please obtain clear permission from the owner / relevant authorities before attempting to access any site – do NOT trespass!
The Low Frequency Radio Range was the United States’ answer to developing a reliable all-weather commercial aviation industry, but as the Second World War loomed at the close of the 1930’s it was clear LFR would go on to play a crucial military role. As the US Government prepared for the inevitable war, one of its first great tasks would be to ultimately manufacture 300,000 warplanes for itself and the Allied Forces and simultaneously train 2.3 million pilots, airmen, ground grew, mechanics, etc. in the Army Air Force to fly them. Hundreds of new Army Airfields popped up across the country to handle this sudden demand, many with a range station to guide and train the new aircrews. The Royal Air Force in Canada responded similarly and developed its first cross-country “Green One” air route with a 3,000-mile line of airbases and range stations.
The second herculean task would be to safely deliver this immense number of aircraft, personnel and materiel across two vast oceans to the Allied Forces that desperately needed them in Europe and Asia. Within a year the Allied Transport Commands created several ferry routes, each thousands of miles long, with regularly spaced air fields, range stations, and other infrastructure to allow aircraft (especially shorter-range twin-engine bombers and fighters) to safely make it to their destination in a series of "hops." Several major ferry routes were established as follows:
LFR’s navigation beams and communications line helped ensure that the planes and supplies made the journey, regardless of weather. Other key strategic areas that benefited from limited LFR coverage included the north coast of Africa along the Mediterranean and later, both ends of “the Hump”, the perilous supply route between India and China over the Burmese Himalayas. Additional stations were provided in the Marianas (Tinian and Guam) to support the bombing efforts against Japan.
There was a terrible price paid for sending so many rapidly trained and inexperienced young men over vast, uninhabited stretches of the earth in complex aircraft: just on the Northwest Route alone, over 133 planes and their aircrews never made it from the US to Fairbanks. Although millions made it to their destinations, a testament to the Transport Commands’ ability, thousands would be lost to adverse conditions as well as enemy action along these routes by war’s end.
After the war was over, much of North America, Western Europe and other once remote parts of the globe were blessed with an extensive network of airfields and range stations that became the foundation of the postwar aviation boom. Very likely, if you are in the US or Canada, your local municipal airport was born in this era. Although Europe had other solid radio navigation options, the expanding presence of US airlines and military forces kept a small network of familiar LFR stations in operation here and in other parts of the Pacific Rim until they were finally supplanted by VORs. Some old airfields and a few dozen range stations though were truly surplus with no real civilian need after the war, and faded from the landscape and charts during the 50’s and 60’s (in a few cases after a brief stint as a drag racing strip).
The air traffic control techniques and operational procedures developed during the war that successfully moved so many planes across the sky laid the groundwork for the world-wide system we take for granted today. The new long-range routes established across the Atlantic were adopted by commercial airlines and they sought the experienced wartime pilots that flew them to handle the post war travel surge. Gander, Shannon, the Azores and Canary Islands became common stops until the jet age finally enabled direct non-stop crossings of the Atlantic. The routes across the Canadian and Alaskan Wilderness would help open the area to the oil exploration that followed in the 60’s and 70’s. These routes were also used by the US and its NATO Allies in ensuring military readiness during the Cold War.
In short: the impact of the Low Frequency Range extended well past the borders of the United States and played a seminal role, among many other international contributions, in shaping global aviation history.
For the United States and Lower Canada, the August 1944 Army Air Force Radio Facility Charts (AAFRFC) has been a “go to” primary source for locating old ranges, it provided what we would now call IFR (Instrument Flight Rules) en-route charts between major airports and range stations, as well as details of each facility. The 1955 Alaska Flight Information Manual (“Alaska FIM”) provided similar data for that state. In addition, we combed through US and some Canadian Sectional Aeronautical Charts (SAC’s) that can be found online especially at the Library of Congress, World Aeronautical Charts (WAC’s) that provided coverage of many parts of the globe, Route Charts (RC’s) and Radio Direction Finding Charts (RDF’s) all from the 1930’s through the early 60’s. Army Air Force Charts (AAF) provided coverage of many international areas during the Second World War as described below. There was a profusion of these charts and other manuals produced during and right after World War II. As of 2020, much of this material is working its way onto eBay and other sources from estate sales and other private collections. We’ve made a few of the more critical pages of the August 1944 AAFRFC available under the Resources tab.
The AAFRFC and Alaska FIM have tables that provide the latitude and longitude of many US stations. There were a few spurious errors in this table here and there, e.g. a latitude and longitude switched, the given coordinates for a couple of sites seemed far from the nominal city (e.g. Atlanta – now corrected). But the data is generally accurate for 95%+ of most sites, and coordinates are provided to the nearest arc second. This sounds great as, in theory, an accuracy of one second of arc works out to be roughly 100’ on the ground. When the aerials were reviewed a few of these coordinates were indeed spot on; however, for most sites it became clear that the actual accuracy of the AAFRFC table ranged from a few hundred feet to a half mile, sometimes more. I personally believe that all of these errors were cause by limitations of the technology of the age (paper maps and scales), especially when the cartographers were constantly updating and disseminating this information during a frenzied wartime environment. Half/quarter mile accuracy was certainly good enough for this system, and I can’t imagine that a deliberate error would be enough to throw off an enemy agent attempting to locate a range station (something with five 135’ towers is indeed hard to hide).
Despite the location errors, many stations were easy to identify using current or historic aerials from the 30’s through 1960’s. Fortunately, most had a distinct square boundary and the blockhouse and antenna were clear. However, this was not always the case – the boundary could be disguised by underlying vegetation and other visual ground clutter. Additionally, these older aerials varied greatly in resolution – in some cases stations were quite clear down to detail of the antenna supports. Other aerials were so low-res that the blockhouse could barely be seen much less the antennae, especially if the sun was directly overhead when it was taken. In a few select cases historic USGS maps located range stations well enough to help with a positive ID, and in other cases contemporary aeronautical sectional charts provided enough clues (e.g. nearby rivers, intersections, airports) to help with an identification. Through this process we’ve been able to positively ID many stations and we’ve categorized them as “Confirmed” as described above.
A few LFR station sites ultimately became Formerly Used Defense Sites (FUDS) that had to undergo environmental cleanup during the late 20th and early 21st centuries. The United States Army Corps of Engineers (USACE), EPA and other agencies-maintained records of these efforts that helped identify sites.
Outside of the US, it was a bit tougher to locate LFR station sites. The resources described above made it easy to locate US stations by identifying them off of old sectionals, then finding contemporary historic aerials or topo maps to geolocate the site. As the US Army Air Forces and Allies expanded their reach and the use of LFR across the globe, their cartographic departments produced the necessary WAC, AAF and Route Charts that showed station locations, albeit at a larger scale than the sectional charts, through the 1960’s. However, finding corresponding pre-1970's historic aerials and topo maps in other countries was often challenging. Also, while many LFR stations endured at foreign hubs heavily trafficked by US aviation, many other more transient wartime stations were removed shortly after the war’s end and were not well documented. Here are some regional specifics:
Although this all made it harder to find stations in these regions, we still believe that most, if not perhaps all, are reflected on the map above. Over time, we hope that many of these locations can be better refined/updated once appropriate aerials and other data can be found. If anyone has information in these areas, please reach out below.
For these people who really want to go into depth, here are is some additional information that came out of our research.
Inclusion of Homing Beacons in the AAFRFC: The 1944 AAFRFC listed 34 “Homing” beacons or NDB's among the US LFR stations we included on the map above. We’ve excluded NDB’s from later years, but we noted that that many on this list were converted from older LFR sites, or were constructed as complete range stations that were fully activated later on (in some cases, such as with Hamilton AFB in California, the LFR capability was never used). Given this ambiguity, we decided to include these first-generation “AAFRFC” NDB’s.
Low Power Airport Range Stations: During the 1930’s, some airports and airlines maintained small, low power loop ranges (type “ML”) that were 50 watts in power and had a 15-mile range that allowed an aircraft to home in more directly to an airport. It was certainly not as good as a localizer or modern-day instrument landing system but it was a helpful aid. As these systems were smaller, they were never noted on topo maps nor do they show on the few early aerial photos available so we could not geolocate these. Here is a list of the ones we’ve identified:
Proposed / “Under Construction” Stations that never entered service. Finally, again in the 1930’s, a number of stations were proposed or listed as Department of Commerce Lists, some were even marked as “Under Construction” on sectional charts, but it appears they never saw actual service (e.g. have beams radiating from this location on a sectional). As we assume that there is little / no physical evidence to locate them these were also not geolocated. Here is a list of the ones we’ve identified:
Note: Alturas, CA was constructed in 1944 but was never shown as an active station on the sectionals. It appears it may have been one of a string of new stations (including Fallon and Tonopah, Nevada) that were constructed during late World War II to provide an inland route from Las Vegas to the Pacific Northwest that was never fully completed, perhaps unneeded after the war’s end? As this station has extensive remnants it was mapped above.