AF1 uses the normal civilian aviation frequencies. For some odd reason, pilots on aircraft flying in airspace occupied by lots of other aircraft think it's a good idea they all be able to listen to each other. Accordingly, AF1 uses plain Jane frequencies used by everybody else. I don't ordinarily listen to the aviation bands, but when AF1 is in the air, anybody with a scanner that does receive aviation frequencies can hear the pilot of AF1 talking to nearby facilities.
Let's what we have for Missoula:
KMSO, Missoula International Airport
Airport Communications
CTAF: 118.4 {i.e. 118.4 MHz, AM. Most scanners will be able to hear this.}
UNICOM: 122.95
ATIS: 126.65
WX ASOS: 126.65 (406-728-3743)
MISSOULA GROUND: 121.9 [0600-2200]
MISSOULA TOWER: 118.4 377.175 [0600-2200]
SPOKANE APPROACH: 124.9
SPOKANE DEPARTURE: 124.9
IC: 124.9
APCH/DEP SVC PRVDD BY SALT LAKE ARTCC ON FREQS 133.4/285.4 (MILLER PEAK RCAG) WHEN APCH CTL IS UNAVBL FOR MSO FROM 2320-0700.
MILLER PEAK RCO 122.45 (GREAT FALLS RADIO)
Very High Frequency (VHF-AM)
Radio frequency range from 30 MHz to 299 MHz. The sub-bands most commonly used by fire are:
VHF-FM Lo band: Frequency Modulation 30 MHz - 80 MHz, of which fire frequencies are between 30 MHz and 50 MHz.
VHF-FM Hi band: Frequency Modulation 150 MHz - 174 MHz. This is the most widely used band by fire agencies.
VHF-AM: Amplitude Modulation. This band is commonly referred to as the "Victor or VHF" band. The frequency range is from 118 MHz to 136 MHz. The only authorized use of this band is for aviation. The FAA controls and assigns all frequencies within this sub-band.
Acronym:
VHF-AM