What is "runups"

Usage examples of "runups".

There were a few onlookers outside the Runway Restaurant at the entrance to the little airport, the usual assortment of people that hung around airports day or night, but when they saw the airplane with the tarps over it, they assumed it was being fixed, so few paid it any more attention--onlookers came to see takeoffs and landings, not engine runups or fuel tanks being drained or scrubbed out.