all the vhf sets have 2 bands AM/FM.....(these are being used by the civilian aircraft)
it possible to catch the random frequencies ...this is also experienced by us while flying as well...we sometimes used to catch even the transmission of mobile phones or vfones etc,....and this used to jam our normal communication
...but this all is zone specific...
its normal to intercept such kind of transmission....
but it is difficult to intercept the transmission of military aircraft since they operate on UHF frequencies and they are a bit secure....
rest vhf sets are available in the market, like Motorola sets being used by police and rangers ...
these can also tune in all the vhf frequencies....
even if you happen to live very close to ATC tower some times the tx (transmission) can be heard on different channels of your TV set...
I hope it clarifies some of the doubts....