see, you can easily tweak a basic fm radio to receive civil aricraft frequencies . now what i mean by basic is an FM radio without synthesiser tuning.like the ones which you can tune with a variable capacitor.
now heres how....
locate the antenna tuning coil. one easy method is to tune the radio onto some station and then bring a metallic screwdriver near the coil. if the radio drifts and the station does not come in clearly, u hit it.....thats the main tuning coil.
now stretch out that coil slightly. when the coil turns are more apart, its inductance is less. so ur tuning range increases.
now you will see a few IF transformers. one of them is to prevent AM noise from getting into the reception.
now aircraft transmissions are in AM so AM noise is exactly what u need.
take a plastic screwdriver and turn the core of the IF transformer slowly until you hear quite a lot of noise comin in.....its kind of finished now
take it near an airport and try tuning in....when i mean near, i mean a few km....tryin to get into the airport with a thing like this will get u arrested!!
even if you are not very near an airport, you can hear transmissions from aircraft flying by..
Civil aircraft use 108MHz to 135MHz