So I guess the key factor is to create a little slack in your schedule so you have time for the unscheduled.

FORBES: Making The Change

By the time Mr Netanyahu joined Mr Clinton for their second, unscheduled meeting, he had neatly sandwiched the president, vice-president and the secretary of state, Madeleine Albright, between friendly evangelists and appearances on talk-shows.

ECONOMIST: America and Israel

Shortly before takeoff, Mr. Hoy said, the pilot said the jet was going to make an unscheduled fuel stop in Gander due to high winds but would try to get passengers to Dulles in time to make connections.

WSJ: Nonstop Flights Stop for Fuel