nonscheduled
adjective
non·sched·uled ˌnän-ˈske-(ˌ)jüld 
-jəld
: licensed to transport by air without a regular schedule
nonscheduled airlines
Example Sentences
Recent Examples on the Web The budget passed in June includes $5.85 million for nonscheduled overtime. 
Darcy Costello, The Courier-Journal, 20 Sep. 2021 This includes most nonscheduled broadcasts, special reports and coverage of major events, including presidential and congressional elections and the papal succession. ABC News, 11 Feb. 2020
Darcy Costello, The Courier-Journal, 20 Sep. 2021 This includes most nonscheduled broadcasts, special reports and coverage of major events, including presidential and congressional elections and the papal succession. ABC News, 11 Feb. 2020 Word History
First Known Use
1929, in the meaning defined above