Flight number record

UA 1434

United Airlines · Washington to San Francisco

Route: IAD → SFO
Departs: 12:35
Flights: 279
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s UA 1434, check with United Airlines.

UA 1434 lands a B+, about a point better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 279 flights, with a median arrival 4 minutes early.

On time

78.4%

Arrivals under 15 minutes late, of 278 completed flights

Avg delay

70 min

Across delayed arrivals only, not all flights

Cancelled

0.36%

National rate is 1.81%

1 hour+ late

8.3%

National rate is 8.1%

These figures cover 279 flights between July 2025 and June 2026. Beyond the headline rate, 8.3% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Schedule

When UA 1434 flies

UA 1434 is scheduled to leave Washington (IAD) at 12:35 local time and reach San Francisco (SFO) at 15:23. That slot held for 238 of the 279 scheduled departures in the data, so the figures below describe one steady operation rather than a number that moved around the clock.

Departs 12:35238 flights85.3%
Departs 12:4041 flights14.7%

Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.

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 78.8%, and UA 1434 runs level with that at 78.4%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

UA 1434 next to IAD to SFO

Every carrier on IAD to SFO combined arrived on time 78.2% of the time across 2,787 flights, so UA 1434 is about level with it. United flew 2,688 flights on the same city pair under all its flight numbers, including this one, and those ran 78.6% on time. Across its whole network United Airlines managed 79.0%, close to this flight's figure.

UA 1434 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
UA 1434thin sample	279	78.4%	70 min	0.36%	B+
All United Airlines on IAD–SFO	2,688	78.6%	74 min	0.89%	B+
All carriers on IAD–SFO	2,787	78.2%	74 min	0.90%	B+
United Airlines, whole network	821,041	79.0%	72 min	1.01%	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 97.7% on time and its weakest Apr–Jun 2026 at 73.6%, a swing of 24 points on roughly 70 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 202543 flights97.7%
Oct–Dec 202592 flights76.9%
Jan–Mar 202653 flights73.6%
Apr–Jun 202691 flights73.6%

Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.

By weekday, UA 1434 did best on Thursday at 85.0% on time and worst on Sunday at 67.5%. Each day rests on about 40 flights, so a gap of 18 points is worth noticing but could still narrow in another year.

Delay causes

Why UA 1434 runs late

One category carries most of the weight here. National Airspace System accounts for 59% of the 4,177 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

National Airspace System
59%
Carrier
25%
Late-arriving aircraft
16%

59% 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 2,477 minutes out of 4,177, against a national NAS share of 21%. The split is drawn from 4,177 delay minutes reported on UA 1434.

Cancellations are rare at 0.36%, below the national 1.81% 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 8.1%. That is the figure that decides a connection, and it says 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 SFO to SAN (246), JAX to IAD (165) 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. 279 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 78.4% on time with 0.36% cancelled over 279 flights. Those are rates from the past twelve months, not a forecast for any particular day.

Where to go next

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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures