"On standard trannies without a proper preselector for "mirror frequency surpression" all Air Band frequencies can be heard at (freq - 21.4) MHz, as this is double of the Intermediate Frequency of the radio (10.7) and called "mirror frequency". FM demods usually demodulate AM well enough to get a good understanding."
Thanks, threemiles - that's interesting! But does it explain why I occasionally pick up Classic FM on 119.7 and/or 121.725 (EGNT Tower and Ground frquencies), while listening on an air band radio?