Talking to the World From Pan Am's Clippers by Francis Allan Chapman (1999)
Right behind the pilots flying Pan Am’s romantic flying boats were the flight radio officers, and this book provides some great insight and fine stories about the experiences of one of that elite group, who kept the clippers in touch with the world on their long flights.
https://www.amazon.com/Talking-world-Pan-Ams-clippers/dp/0911868917/