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 3878 LANDED 9:46 PM MT, ~11 MIN LATE · SCHEDULED TIME UNKNOWN

Tuesday, September 29 Yesterday

WN 3878 · STL → PHX

took off 8:57 PM CT · landed 9:46 PM MT (scheduled time unknown)

Forecast issued Tue 10:00 PM ET · 0h before departure

Arrive at PHX more than 15 minutes late?

31% chance · ±1 pts +5 pts · 24h

HOW SURE WE ARE Very high. The odds now come almost entirely from live conditions.

What’s moving the odds

↑ Arrivals into PHX at that hour are often late

↑ Later flights pick up delays from earlier in the day

↑ Cloud base down to 1,300 ft, visibility down to 0.5 mi, 0.3 in of rain, thunderstorms forecast at PHX that day

↓ Tuesdays in September are usually quieter than average

↓ Mostly benign weather forecast at STL

Weather at each end

STL (origin) Gusts9 kt Ceilingnone (clear) Visibility10+ mi Precipnone

PHX (destination) Gusts21 kt Ceiling1,300 ft Visibility0.5 mi Precip0.34 in

How this resolves

Yes if the gate arrival is more than 15 minutes after the scheduled arrival. Cancelled or diverted flights resolve N/A.

Every question here is display only — there is no betting or money involved. Gate times come from the airline; a cancellation resolves only the “Cancelled?” question, and a diversion voids the delay questions.

WN 3878 · STL → PHX

Odds over time