Tracked live by the FAA, but its flight plan was first seen after takeoff, so we don't know the scheduled time and can't say whether it's late.

SOUTHWEST · FLIGHT WN 4181 IN THE AIR (OFF 4:18 PM CT, ETA 6:36 PM ET) · SCHEDULED TIME UNKNOWN
Today

WN 4181 · BNA → DCA

took off 4:18 PM CT · expected to land 6:36 PM ET (scheduled time unknown)
Forecast issued Tue 4:00 PM ET · 1h before departure

Odds over time

Arrive at DCA more than 15 minutes late?
26% chance · ±0 pts −4 pts · 24h
HOW SURE WE ARE High. The odds now come mostly from live FAA and airport data.
WEATHER FORECASTS LIVE IN THE AIR 0% 10% 20% 30% 40% 1.1d 12h 6h Now Departs Lands