Flight number record
UA 1434
United Airlines · Washington to San Francisco
- Route
- IAD → SFO
- Departs
- 12:35
- Flights
- 328
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 1434, check with United Airlines.
UA 1434 lands a B+, level with the national rate of 77.3%. Roughly one flight in four arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That rests on 328 flights, with a median arrival 4 minutes early.
Key figures
On time
77.4%
Arrivals under 15 minutes late, of 327 completed flights
Avg delay
68 min
Across delayed arrivals only, not all flights
Cancelled
0.30%
National rate is 1.89%
1 hour+ late
8.3%
National rate is 8.3%
These figures cover 328 flights between September 2025 and August 2026. Beyond the headline rate, 8.3% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When UA 1434 flies
UA 1434 flies IAD to SFO without a single fixed slot. Its most common scheduled departure was 12:35, used on 225 of 328 flights, with 12:40 (103 flights) next.
- Departs 12:35225 flights68.6%
- Departs 12:40103 flights31.4%
Scale runs 0% to 100%.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 12:35 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and UA 1434 runs level with that at 77.4%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
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Against the route
UA 1434 next to IAD to SFO
Every carrier on IAD to SFO combined arrived on time 77.5% of the time across 2,688 flights, so UA 1434 is about level with it. Across its whole network United Airlines managed 78.8%, close to this flight's figure.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 1434thin sample | 328 | 77.4% | 68 min | 0.30% | B+ |
| All United Airlines on IAD–SFO | 2,688 | 77.5% | 72 min | 0.71% | B+ |
| All carriers on IAD–SFO | 2,688 | 77.5% | 72 min | 0.71% | B+ |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 1434 quarter by quarter
UA 1434 did not run the same all year. Its best quarter was Jul–Sep 2025 at 96.7% on time and its weakest Apr–Jun 2026 at 73.6%, a swing of 23 points on roughly 66 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202530 flights96.7%
- Oct–Dec 202592 flights76.9%
- Jan–Mar 202653 flights73.6%
- Apr–Jun 202691 flights73.6%
- Jul–Sep 202662 flights77.4%
Scale runs 65% to 100%.
By weekday, UA 1434 ranged from 70.2% on Sunday to 80.9% on Thursday. With about 47 flights behind each day, a spread of 11 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late UA 1434 runs when it is late
UA 1434 often beats the schedule: 91 of 327 completed flights, 28%, arrived 15 minutes or more early. The 74 late arrivals split 27 under half an hour, 20 between 30 and 60 minutes, and 27 an hour or more.
- 15+ min early91 flights27.8%
- Within 15 min162 flights49.5%
- 15–29 min late27 flights8.3%
- 30–59 min late20 flights6.1%
- 1–2 hours late17 flights5.2%
- 2+ hours late10 flights3.1%
Scale runs 0% to 100%.
Share of 327 completed flights by arrival against schedule.
19 of 71 late departures made up the time and arrived on time, 27% of them. In the other direction, 22 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SFO.
The worst days
Worst days for UA 1434
The latest arrival of the period was on 18 July 2026, 6 hours 29 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. Three of the five worst days fell in December 2025.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 18 July 2026 | 6 hours 29 minutes | Late-arriving aircraft |
| 16 December 2025 | 4 hours 35 minutes | Carrier |
| 5 January 2026 | 4 hours 26 minutes | National Airspace System |
| 25 December 2025 | 4 hours 21 minutes | National Airspace System |
| 9 December 2025 | 3 hours 11 minutes | Late-arriving aircraft |
Delay causes
Why UA 1434 runs late
National Airspace System accounts for 55% of the 5,048 delay minutes carriers reported here, and the remaining four split what is left.
- 55%National Airspace System
- 23%Carrier
- 19%Late-arriving aircraft
- 3%Extreme weather
55% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 2,757 minutes out of 5,048, against a national NAS share of 21%. The split is drawn from 5,048 delay minutes reported on UA 1434.
Cancellations are rare at 0.30%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and routes
What a delay on this flight costs
8.3% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last a little over an hour, which a normal layover absorbs.
At 2,418 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The same number turns up on five other city pairs in the data, including JAX to IAD (212), SFO to SAN (184) and SFO to RNO (35), but none flew often enough under UA 1434 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to IAD to SFO only.
One caution: this is a thin sample. 328 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking UA 1434
For a booking, read UA 1434 as 77.4% on time with 0.30% cancelled over 328 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- IAD to SFO, every carrier and departure
- SFO to IAD, the return direction
- United Airlines 1757 on the same route58.8%
- United Airlines 2862 on the same route80.8%
- United Airlines 367 on the same route82.6%
- United Airlines 1095 on the same route85.0%
- Washington Dulles International (IAD) delay statistics
- San Francisco International (SFO) delay statistics
- United Airlines on-time record
- Every United Airlines flight number with a record
- The most and least reliable flight numbers in the US
- Worst months to fly in the US, ranked by the data
A flight number here means United Airlines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.