I have tried programming approach frequencies into my baofeng and cannot hear any transmissions. Freq programming was done using a desktop computer connected to the radio to frequency 121.9MHZ. Nothing was heard, just standard background static. Here is the radio: https://www.amazon.com/Baofeng-Warranty-Dual-Band-Radio-Improved/dp/B00HX03AMA Baofeng UV5R v2
As far as I've read, all Baofeng radios do FM only. The majority of aircraft communications uses AM, so whether or not it can be tuned there, you would not hear the audio, just approximate silence (quieter the stronger the signal).
This is because to a FM receiver's perspective, an AM signal is unmodulated (the frequency stays constant), and vice versa (in a FM signal the amplitude stays constant).
In some cases, the speech may be very faintly audible, due to imperfect circuits in both the transmitter (causing frequency variation in the transmitted signal) and the receiver (having unintended sensitivity to amplitude variations).
In the reverse case — attempting to receive a FM signal using an AM receiver — this can actually be used practically (improvised “slope detection”, tuning with an offset and allowing the frequency modulated signal to be converted by the edge of the receiver's filter to an amplitude-and-frequency modulate signal).
From the amazon page you've linked to:
Frequency Range: 136-174 / 400-479.995 MHz.
So, no, you can't receive 121.9 MHz.
Yes, it can receive air band transmissions but upper the frequency limit is 127 MHz or 128 MHz. I can get the airport but the speech very faintly audible. This is because from an FM receiver perspective, an AM signal is unmodulated.
Anyway, I can receive AM signals with a Baofeng UV5R but the sound is awful. You can watch my videos on youtube kourosh delpak or instagram radiofrequency.ep https://www.instagram.com/p/Bo9MTg1DCdT/?taken-by=radiofrequency.ep