Earlier quoted context omitted.
You should still be able to do this with a cheap RTL-SDR dongle (<$20) and a laptop, though you will probably look pretty conspicuous to the flight attendants
I think there are FAA or airline rules against passengers on commercial flights using aviation radios -- and those rules might include aviation radios that you synthesize yourself. https://aviation.stackexchange.com/questions/8939/can-i-fly-... (It seems that the rules are meant to avoid having unexpected devices onboard using aviation-related RF energy, rather than to prevent passengers from monitoring aircraft comm…
But if one can get an old analog FM radio, something can be done eaasily. The air radio band (118 to 136 MHz) is just above the FM broadcast band (76 or 88 to 108 MHz), and airliners use AM modulation rather than FM, but old consumer radio FM demodulators demodulate AM as well, so all one needs to do is retuning the radio on airband frequencies. This can be done by altering some values in the frontend and local oscillator LC stages, but sometimes is enough just to widen the oscillator coil to tune the radio a few MHz up. Nobody should object if you listen to an old FM pocket radio with headphones from your seat.