UA939 LondonLHR · 16:15 San FranciscoSFO · 19:15
UA939 by United Airlines flies from London (LHR) to San Francisco (SFO).
scheduled from LHR
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
Weather-conditioned outlook for this flight right now
Measured, 90-day sampleDriven mainly by SFO (San Francisco), currently flying VFR (visual). These figures come from both airports' records 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 →
Tomorrow on this route
ForecastLondon to San Francisco with United Airlines · Mon 2 Nov, local date
- Chance a departure is cancelled
- 0.7%1.3× usual
- Chance a departure leaves 60+ min late
- 8.7%0.7× usual
Forecast: GateWeather · incl. data from ECMWF (CC BY 4.0, modified) · About 3 departures a day on this route with this airline. · Expected values for tomorrow from a forecast model, kept apart from today's measured figures.
When it flies
scheduled departuresEach mark is a scheduled departure at its origin-local time. Today is highlighted.
Other London to San Francisco flights today
same route · United AirlinesIf UA939 is cancelled, these are the other United Airlines nonstop flights from London to San Francisco on the same day, with scheduled departure times in LHR local time. Most flights that show a delay still operate. Rebooking usually helps only when that delay is very large. Every airline on this route →
How UA939 actually runs
Pro Flight Search has tracked every published board update for UA939 across the LHR and SFO boards: schedule changes, gate pushes and actual clocks. Early read: no clear pattern yet. Only 3 completed legs so far: left noticeably late (~42 min) but landed a little late (~9 min). Not enough to call it.
The verdict above is that record speaking, so it reflects how UA939 operates rather than what the timetable promises. Numbers refresh as new flights operate.
How this operation is measured
Board log
scheduled → actual, per operationBoard clocks recorded as LHR and SFO published them.
Planning around UA939? 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: UA939 London to San Francisco on-time performance, measured from the LHR and SFO airport boards.
https://proflightsearch.com/flight/UA939
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