Carrier route record
UASAN→IAD
United Airlines · San Diego to Washington
- Flights
- 1,040
- Period
- July 2025 to June 2026
- Share of route
- 74%
- Carriers
- 2
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on SAN to IAD earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 12 points better than the national rate of 77.6%. When something does go wrong the average delay runs an hour and a half. That rests on 1,040 flights, with a median arrival 14 minutes early.
Set against the rest of the country, United's SAN to IAD record is 12 points better than the US average of 77.6%. That gap is worth roughly 119 fewer late arrivals for every thousand flights.
Key figures
On time
89.5%
Arrivals under 15 minutes late, of 1,028 completed flights
Avg delay
87 min
Across delayed arrivals only, not all flights
Cancelled
0.48%
National rate is 1.81%
Whole route
89.0%
Every carrier on SAN to IAD, 1,400 flights
These figures cover 1,040 flights between July 2025 and June 2026. The median arrival is 14 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Carrier by carrier
United against every carrier on SAN to IAD
United flew 1,040 of the 1,400 flights on SAN to IAD, most of the route. Its 89.5% on time is about level with the route as a whole at 89.0%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from United at 89.5% to Alaska at 87.6%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines (this page) | 1,040 | 89.5% | 87 min | 0.48% | A+ |
| Alaska Airlinesthin sample | 360 | 87.6% | 56 min | 0.83% | A+ |
Flight by flight
United flight numbers on SAN to IAD
Departure window
When United runs best on this route
Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 1,040 flights.
- 5am–8am65 flights84.1%
- 8am–11am287 flights87.3%
- 11am–2pm362 flights91.6%
- 2pm–5pm—
- 5pm–8pm—
- 8pm–5am326 flights90.1%
Scale runs 75% to 95%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 11am–2pm slot at 91.6% on time, ahead of 5am–8am at 84.1%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 11am–2pm window is the busiest, with 362 flights scheduled in it.
Across the year
United on SAN to IAD through the year
Delays peak in March, when the on-time rate falls to 81.7%. February is the strongest month at 95.8%. Moving a flexible trip across that boundary buys 14 points. August was the busiest month here, with 93 flights.
Across the week, Tuesday is the strongest day at 95.1% on time and Sunday the weakest at 86.0%. 9 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United runs late on this route
One category carries most of the weight here. Carrier accounts for 44% of the 9,439 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.
- 44%Carrier
- 26%National Airspace System
- 16%Extreme weather
- 15%Late-arriving aircraft
Extreme weather accounts for 16% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.5 times the usual weather exposure. The split is drawn from 9,439 reported delay minutes.
The largest share of delay minutes, 44%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 4,175 of the 9,439 delay minutes reported here.
Cancellations are rare at 0.48%, 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 stage length
What a delay here costs
Badly late arrivals are rare here: only 3.0% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
At 2,253 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 return leg runs 87.1% on time across 1,040 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
One caution: this is a thin sample. 1,040 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 United on SAN to IAD
Put together: treat all of this as provisional. 1,040 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 89.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,028 completed flights over 12 months sit behind that.
Related
Where to go next
- SAN to IAD, every carrier
- United on IAD to SAN, the return leg
- Alaska Airlines on SAN to IAD87.6%
- United Airlines network-wide record
- San Diego International (SAN) delay statistics
- Washington Dulles International (IAD) delay statistics
- Worst months to fly in the US, ranked by the data
- Late aircraft, weather, or the airline: what actually causes US flight delays
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.