Route reliability record
SAN→IAD
San Diego to Washington
- Flights
- 1,402
- Period
- September 2025 to August 2026
- Distance
- 2,253 mi
- Carriers
- 2
This route 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 10 points better than the national rate of 77.3%. When something does go wrong the average delay runs a little over an hour. That rests on 1,402 SAN to IAD flights, with a median arrival 12 minutes early.
Best time to fly SAN to IAD: a 11am–2pm departure, ideally on a Tuesday. Flights in that window arrived on time 87.7% of the time and Tuesday flights 94.3%, against 87.6% for the route overall.
Set against the rest of the country, this route's record is 10 points better than the US average of 77.3%. That gap is worth roughly 103 fewer late arrivals for every thousand flights.
Key figures
On time
87.6%
Arrivals under 15 minutes late, of 1,384 completed flights
Avg delay
74 min
Across delayed arrivals only, not all flights
Cancelled
0.78%
National rate is 1.89%
Best carrier
United
88.0% on time across 1,041 flights
These figures cover 1,402 flights between September 2025 and August 2026. The median arrival is 12 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.
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Carrier by carrier
Which airline is most reliable on SAN to IAD
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 | 1,041 | 88.0% | 81 min | 0.77% | A+ |
| Alaska Airlinesthin sample | 361 | 86.3% | 57 min | 0.83% | A+ |
Flight by flight
Flights on SAN to IAD
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly San Diego to Washington
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 1 of the top 2 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SAN → IADSan Diego to Washington | United Airlines | 87.3% | 88.0% | 0.77% | 8am–11am, Tue | UA 1071 08:00 |
| 2. SAN → BWISan Diego to Baltimore | Southwest Airlines | 75.3% | 76.6% | 1.69% | 5am–8am, Sat | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
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 1,402 flights.
- 5am–8am16 flights—
- 8am–11am695 flights87.6%
- 11am–2pm363 flights87.7%
- 2pm–5pm2 flights—
- 5pm–8pm—
- 8pm–5am326 flights87.3%
Scale runs 80% to 95%. Rows with fewer than 30 flights show a dash.
The overnight block holds up unusually well at 87.3% on time across 326 flights. Red-eyes fly into empty airspace and empty gates, and they are the first rotation of the aircraft's day rather than the last. The 8am–11am window is the busiest, with 695 flights scheduled in it.
Explore
Filter SAN to IAD by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On SAN to IAD, the best departure window is 11am–2pm at 87.7% on time and the worst is 8pm–5am at 87.3%, a narrow gap of 0.4 points. All US flights leaving 11am–2pm ran 78.3%.
- 5–8am—
- 8–11am87.6%
- 11am–2pm87.7%
- 2–5pm—
- 5–8pm—
- 8pm–5am87.3%
best all US flightsScale 60% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 26 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
July is the worst month at 69.4% on time, 26 points below October, the best at 95.0%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. July was the busiest month here, with 124 flights.
Across the week, Tuesday is the strongest day at 94.3% on time and Sunday the weakest at 82.3%, a spread of 12 points.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 13,000 reported delay minutes.
- 39%Carrier
- 25%Late-arriving aircraft
- 23%National Airspace System
- 13%Extreme weather
Extreme weather accounts for 13% 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 2.2 times the usual weather exposure. The split is drawn from 12,704 reported delay minutes.
The largest share of delay minutes, 39%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 4,934 of the 13,000 delay minutes reported here.
Cancellations are rare at 0.78%, 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 stage length
What a delay here actually costs
Badly late arrivals are rare here: only 3.5% land an hour or more behind schedule, against 8.3% 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 is a different operation and performs like one: it runs 82.9% on time across 1,402 flights, 5 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 5 points of difference.
The sample behind these figures is 1,402 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in IAD after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. October runs 95.0% on time and July 69.4%, a swing of 26 points. If the dates move at all, move them out of July before you think about anything else. 1,384 completed flights over 12 months sit behind that.
Common questions
SAN to IAD questions
How often is SAN to IAD delayed?
About one flight in eight arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 12.4% of the 1,402 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
How reliable is SAN to IAD compared with the rest of the country?
87.6% of flights arrive on time here against a national 77.3%, a difference of 10 points in its favour. That is worth a A+ on this site's grading scale.
Does the departure time change the odds on SAN to IAD?
Not by much in this data. Every departure window falls within half a point of the others, so there is no hour worth rearranging a trip for. The overall rate of 87.6% is the figure to plan against.
How bad are July delays on SAN to IAD?
July is the weakest month at 69.4% on time, compared with 95.0% in October. Across the year that is 26 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- IAD to SAN — the return legseparate record
- San Diego International (SAN) delay statistics
- Washington Dulles International (IAD) delay statistics
- United Airlines on SAN to IAD88.0%
- Alaska Airlines on SAN to IAD86.3%
- SAN to SFO, a related route59.5%
- ATL to IAD, a related route76.4%
- SAN to DEN, a related route78.4%
- United Airlines on-time record88.0%
- Alaska Airlines on-time record86.3%
- Worst months to fly in the US, ranked by the data
- Late aircraft, weather, or the airline: what actually causes US flight delays
Direction matters. SAN to IAD and IAD to SAN are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.