UA4257 WashingtonIAD · 09:00 Knoxville/MaryvilleTYS
UA4257 by United Airlines flies from Washington (IAD) to Knoxville/Maryville (TYS) for the Mon, Aug 17 departure.
en route from IAD to TYS
board checked 285m ago · checking again in 45s
Board estimate · gate and arrival times. Off blocks 09:17 · typical taxi-out at IAD ≈ 8.9 min.
Where the minutes go
last 7 operations · gate push → arrivalThe bar is how late it left the gate; the ring is where it actually arrived. Board clocks, not estimates.
The last 30 days
arrival outcome per operation0 cancelled · 13 operations tracked
The route today
live boardsWhen it flies
scheduled departuresEach mark is a scheduled departure at its origin-local time. Today is highlighted.
Other Washington to Knoxville/Maryville flights today
same route · United AirlinesIf UA4257 is cancelled, these are the other United Airlines nonstop flights from Washington to Knoxville/Maryville on the same day, with scheduled departure times in IAD local time. Most flights posting a delay still operate — rebooking usually only beats a very large posted delay. Every airline on this route →
How UA4257 actually runs
Pro Flight Search has tracked every published board update for UA4257 across the IAD and TYS boards: schedule changes, gate pushes and actual clocks. Usually departs ~17 min late. Based on 13 confirmed departures · 6/13 within 15 min of schedule.
The verdict above is that record speaking, so it reflects how UA4257 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: N14198, N14153, N17146, N12142.
Board clocks recorded as IAD and TYS published them.
Planning around UA4257? 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 — UA4257 Washington to Knoxville/Maryville on-time performance, measured from the IAD and TYS airport boards.
https://proflightsearch.com/flight/UA4257
.