The usual suspects
Tour flights. Scenic sightseeing helicopters fly set loops over downtown, the river, and the Plaza — if you see a helicopter tracing a slow, deliberate arc around the skyline on a clear day or at sunset, it's very likely riders enjoying one of the Kansas City helicopter tours.
Medical transport. KC's hospital network runs air-ambulance helicopters at all hours. They fly direct lines at speed, often to and from hospital rooftop pads — the fast, purposeful ones are usually this.
News and traffic. Local stations put helicopters over breaking news, big games, and rush-hour trouble spots. These hover or orbit one location, camera pointed down.
Downtown Airport traffic. Charles B. Wheeler Downtown Airport sits right across the river from the skyline, which is why so much general aviation — helicopters included — crosses the downtown loop at low altitude. It's normal, and it's also exactly what makes the close-up skyline views on tour flights possible.
Law enforcement and military. Police aviation units and occasional military transits round out the list — typically brief, and usually the answer when a helicopter is running a grid pattern or flying at night with a spotlight.
Rather be in one?
The slow scenic one circling the skyline has open seats most weeks. Routes and details are on the tours page, prices are explained in the pricing guide, and the booking walkthrough takes about two minutes.