Military Aircraft Monitoring
Understanding Tactical Frequencies
Tactical frequencies are the hardest ones to find, but there are a number of things that you can do to increase your success.
Know which band to search: We have talked before about how some aircraft use UHF, some use VHF and some use FM. Much of this is related to the aircraft's use. Most fighters and long-range strike aircraft are using UHF. We've noted that some others--notable F-16s and A-10s use VHF. We've also noted the aircraft in the Close Air Support role tend to use FM in order to communicate easily with ground troops.
Search the band in small segments: I never search more than 2 MHz of spectrum at a time. Aircraft transmissions are brief and infrequent. I never try to cover a large band than my scanner can cover in 5 seconds.
Go from the narrowest ranges to the widest: VHF is the easiest band in practical terms, and UHF is the widest (possibly 7,000 channels at 25 kHz spacing) I first search increments between 138-144 in AM mode. Three guys, each scanning 2 MHz can easily cover this band in a short time. Next in difficulty is FM. Start with the most frequently used bands at 38, 36 and 40-42 MHz. Follow up with 34, 32, 46 and 49 MHz segments. Then check 50-54, and 54-66. Very little FM is reported above 66 MHz.
Understand how tactical frequencies are often selected: Three considerations seem to prevail in the selection of tactical frequencies. First is to find numbers that are easy to remember, and the second is to set them up so that frequencies can be changed easily with the least possible manipulation of the radio dial. Third is to have frequencies in use that won't already be in use elsewhere. (Priorities are not necessarily in this order)
Easy to Remember - There are lots of 'cute' numerical patterns. Famous examples include 333.3, 125.125. 252.525, 123.45, 234.5, 242.4, 282.8, 345.67(5), etc. Also there are suggestive patterns such as 300.6 (Thirty Ought-Six), 357.0 (Magnum) and 303.0 which is suggestive of the 30-30 rifle caliber. Zillions of these combinations are possible in the various bands, which makes them even more popular.
Easy to change - Each digit of a manually-input frequency has its own knob on an aircraft radio. Years ago, some A-7Ds in my town were using 36.8, 46.8 and 56.8 for air/air. They had it set up so that they need only turn the 10-MHz knob to change channels. In most cases, though, we're seeing this done with the 1 MHz and 100 kHz knobs. Consider a unit who uses frequencies like 300.025, 300.125, 300.225, up to 301.525 and 301.625. Look again with the 1 MHz and 100 kHz digits in bold: 300.025, 300.125, 300.225, 301.525, 301.625. What do want to bet that these guys call these freqs, "00", "01", "02", "15" and "16"?
Unlikely to Interfere - For years, aircraft radios were made to tune in 50 kHz increments. That means that frequencies like 121.1, and 121.15 were tunable by all, but that frequencies like 121.125 and 121.175 were not available except in aircraft with newer radios. You'll find that many tactical frequencies are on .25 and .75 increments. Most UHF air traffic control frequencies are still on .00 and .05 increments, so that gives those who use the .25 and .75 increments a lot of clear channels to work with. This doesn't work so well in Europe, but should do very well in the US.
Find People to Share Info With: None of us can do this alone. It took extensive info trading before I ever had enough information to even find these trends.
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