Talking to the pilots costs about $200 and is really easy, though very illegal - just find out which ATC freq are they currently on and transmit, from a handhel

Talking to the pilots costs about $200 and is really easy, though very illegal - just find out which ATC freq are they currently on and transmit, from a handheld radio or a HackRF. You could also transmit on Guard. If you prefer to text rather than speak you can send them ACARS, with roughly the same hardware. Though if you use a handheld radio you'll also need a laptop to generate the baseband signal, as I don't think there are any commercially available ACARS transmitters. (Please never do this, you'll go to jail for a long time).