From Longman Dictionary of Contemporary Englishunscheduledun‧sched‧uled /ʌnˈʃedjuːld $ ʌnˈskedʒəld/ AWL adjective not planned or expected The plane made an unscheduled stop in New York.
Examples from the Corpus
unscheduled• Food product quality is more easily maintained thereby reducing spoilage losses and production time through unscheduled cleaning.• Bad weather forced the pilots to make an unscheduled landing.• In 15 of those flights, pilots were forced to make unscheduled landings.• Seven times the aircraft made unscheduled landings.• A slip-up now and an extra, unscheduled recording break will be necessary.• As the southbound train hit the New Hampshire-Maine border, it made an unscheduled stop.• In the handover to Jan Lammers, another new battery was fitted, and then another in an unscheduled stop.• During follow-up, adverse events were looked for systematically at all scheduled and unscheduled visits. 