WN3878 St LouisSTL · 20:45 PhoenixPHX · 22:00
WN3878 by Southwest Airlines flies from St Louis (STL) to Phoenix (PHX) for the Tue, Sep 8 departure.
estimated arrival at PHX · local time
position updated 5m ago · checking again in 90s
Live position · on the ground at STL, taxiing for departure.
Where the minutes go
last 4 operations · gate push → arrivalThe bar is how late it left the gate; the ring is where it actually arrived. Board clocks, not estimates.
The route today
live boardsWeather lens
Delay & cancellation outlook for this flight
Measured, 90-day sampleConditions at STL and PHX are near their clear-air norm right now, so this reflects the route's recent baseline rather than a weather penalty. For this route and airline, under conditions like today's, over the last 90 days.
Pro Flight Search tracking, 90 days · the weather × delay correlation study → · live weather risk by airport →
When it flies
scheduled departuresEach mark is a scheduled departure at its origin-local time. Today is highlighted.
Other St Louis to Phoenix flights today
same route · Southwest AirlinesIf WN3878 is cancelled, these are the other Southwest Airlines nonstop flights from St Louis to Phoenix on the same day, with scheduled departure times in STL local time. Most flights posting a delay still operate — rebooking usually only beats a very large posted delay. Every airline on this route →
How WN3878 actually runs
Pro Flight Search has tracked every published board update for WN3878 across the STL and PHX boards: schedule changes, gate pushes and actual clocks. Usually lands on time. Based on 3 confirmed landings · 2/3 within 15 min of schedule. Pushes back late but makes up time in the air.
The verdict above is that record speaking, so it reflects how WN3878 operates rather than what the timetable promises. Numbers refresh as new flights operate.
How this operation is measured
Board log
scheduled → actual, per operationAircraft
Recent tails: N8978G, N941WN, N8934Q.
Board clocks recorded as STL and PHX published them.
Planning around WN3878? Will a delayed flight be cancelled? · Do planes make up time in the air? · How we measure
Journalists, bloggers, and researchers may cite this page with attribution and a link to Pro Flight Search.
Pro Flight Search — WN3878 St Louis to Phoenix on-time performance, measured from the STL and PHX airport boards.
https://proflightsearch.com/flight/WN3878
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