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.

AMERICAN · FLIGHT AA 1637 LANDED 4:38 PM CT, ~18 MIN LATE · SCHEDULED TIME UNKNOWN

AA 1637 · DCA → ORD

took off 4:09 PM ET · landed 4:38 PM CT (scheduled time unknown)
Forecast issued Tue 10:00 PM ET · 6h after departure

Odds over time

Arrive at ORD more than 15 minutes late?
48% chance · ±0 pts +7 pts · 24h
HOW SURE WE ARE Very high. The odds now come almost entirely from live conditions.
WEATHER FORECASTS LIVE IN THE AIR 0% 15% 30% 45% 60% 1.0d 12h 6h Departs Lands