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 54 SCHEDULED · SCHEDULED TIME UNKNOWN
Yesterday

WN 54 · HOU → DAL

departs 2:30 AM CT · arrives 3:13 AM CT
Your aircraft is N478WN (B737), coming in as WN 973 from ELP: landed 2:09 PM CT.
Forecast issued Sat 11:00 PM ET · 20h after departure

Odds over time

Arrive at DAL more than 15 minutes late?
11% chance · ±0 pts −22 pts · 24h
HOW SURE WE ARE Very high. The odds now come almost entirely from live conditions.
LIVE IN THE AIR 0% 15% 30% 45% 60% 8h 6h Departs Lands