Aircraft Radios and UAV Operators
While using an aircraft radio to monitor aircraft activity, the FAA strongly discourages unnecessary transmissions on aeronautical frequencies.
You can listen, but you cannot transmit unless in an emergency
A handheld radio must be licensed when not used from within an aircraft or under the license of an airport UNICOM radio. The one non-emergency use of a handheld is talking to a flight student who is on a solo training flight.
As with any rule, in the event of an emergency, you can break a rule but you better have a good reason when the FAA calls.