air time vs simulcast

air time

noun

  • The period of freefall after jumping. 

simulcast

noun

  • A program or event that is broadcast across more than one medium or service at the same time. 

verb

  • To broadcast a program or event across more than one medium or service at the same time. 

How often have the words air time and simulcast occurred in a corpus of books? (source: Google Ngram Viewer )