RhymeZone: airtime definitions

Definitions of airtime:

noun: The duration during which a radio or television program (or part of one) is transmitted.
noun: (by extension) The duration spent talking during a conversation.
noun: The chargeable use of a mobile phone, either in minutes or in units dependent on the use or traffic.
noun: The period during which a person riding a rollercoaster or similar ride experiences a feeling of weightlessness.

(Definitions from Wiktionary)