UA4040 HoustonIAH · 16:33 LouisvilleSDF · 19:55
UA4040 by United Airlines flies from Houston (IAH) to Louisville (SDF) for the Wed, Sep 16 departure.
departs IAH · on schedule
board checked 52m ago · checking again in 45s
Where the minutes go
last 3 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
Early read, sample still buildingConditions at IAH and SDF 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. This route's tracked sample is still thin — treat these as an early read, not a precise forecast.
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 Houston to Louisville flights today
same route · United AirlinesIf UA4040 is cancelled, these are the other United Airlines nonstop flights from Houston to Louisville on the same day, with scheduled departure times in IAH local time. Most flights posting a delay still operate — rebooking usually only beats a very large posted delay. Every airline on this route →
How UA4040 actually runs
Pro Flight Search has tracked every published board update for UA4040 across the IAH and SDF boards: schedule changes, gate pushes and actual clocks. Early read — pattern not clear yet. Only 2 completed legs so far: left heavily delayed (~172 min) but landed heavily delayed (~46 min). Not enough to call it.
The verdict above is that record speaking, so it reflects how UA4040 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: N89317.
Board clocks recorded as IAH and SDF published them.
Planning around UA4040? 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 — UA4040 Houston to Louisville on-time performance, measured from the IAH and SDF airport boards.
https://proflightsearch.com/flight/UA4040
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