Route reliability record
IAD→SFO
Washington to San Francisco
- Flights
- 2,688
- Period
- September 2025 to August 2026
- Distance
- 2,418 mi
- Carriers
- 1
This route 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 2,688 IAD to SFO flights, with a median arrival 5 minutes early.
Best time to fly IAD to SFO: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 85.0% of the time and Tuesday flights 86.6%, against 77.5% for the route overall.
The US average over the same twelve months is 77.3%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
77.5%
Arrivals under 15 minutes late, of 2,665 completed flights
Avg delay
72 min
Across delayed arrivals only, not all flights
Cancelled
0.71%
National rate is 1.89%
Best carrier
United
77.5% on time across 2,688 flights
These figures cover 2,688 flights between September 2025 and August 2026. Beyond the headline rate, 8.2% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on IAD to SFO
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 | 2,688 | 77.5% | 72 min | 0.71% | B+ |
Flight by flight
Flights on IAD to SFO
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 Washington to San Francisco
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. 3 of the top 4 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. BWI → SFOBaltimore to San Francisco | United Airlines | 77.2% | 77.9% | 0.90% | 8am–11am, Tue | — |
| 2. IAD → SFOWashington to San Francisco | United Airlines | 76.9% | 77.5% | 0.71% | 5am–8am, Tue | UA 1095 06:30 |
| 3. DCA → SFOWashington to San Francisco | United Airlines | 74.3% | 74.8% | 0.69% | 5am–8am, Sat | UA 369 07:00 |
| 4. BWI → SFOBaltimore to San Francisco | Southwest Airlines | 51.0% | 51.4% | 0.82% | 8am–11am, 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 matters more here than the choice of carrier. The gap between the best and worst window is 22 points, against half a point between the best and worst carrier.
- 5am–8am320 flights85.0%
- 8am–11am456 flights83.7%
- 11am–2pm365 flights78.2%
- 2pm–5pm594 flights82.2%
- 5pm–8pm537 flights62.8%
- 8pm–5am416 flights76.5%
Scale runs 55% to 90%.
The 5pm–8pm window is where this operation falls apart: 62.8% on time, against 85.0% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 2pm–5pm window is the busiest, with 594 flights scheduled in it.
Explore
Filter IAD to SFO 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 IAD to SFO, the best departure window is 5am–8am at 85.0% on time and the worst is 5pm–8pm at 62.8%, a wide gap of 22.2 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am85.0%
- 8–11am83.7%
- 11am–2pm78.2%
- 2–5pm82.2%
- 5–8pm62.8%
- 8pm–5am76.5%
best all US flightsScale 55% to 95%.
Across the year
When delays peak on this route
This route's year swings by 24 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.
June is the worst month at 63.5% on time, 24 points below March, the best at 87.8%. 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. May was the busiest month here, with 268 flights.
Across the week, Tuesday is the strongest day at 86.6% on time and Thursday the weakest at 74.0%, a spread of 13 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 43,000 reported delay minutes.
- 42%National Airspace System
- 28%Late-arriving aircraft
- 26%Carrier
- 4%Extreme weather
42% 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 18,000 minutes out of 43,000, against a national NAS share of 21%. The split is drawn from 43,301 reported delay minutes.
Cancellations are rare at 0.71%, 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
8.2% 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 return leg is a different operation and performs like one: it runs 83.0% on time across 2,690 flights, 6 points above 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 6 points of difference.
The sample behind these figures is 2,688 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 SFO 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. March runs 87.8% on time and June 63.5%, a swing of 24 points. If the dates move at all, move them out of June before you think about anything else. 2,665 completed flights over 12 months sit behind that.
Common questions
IAD to SFO questions
How often is IAD to SFO delayed?
Roughly one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 22.5% of the 2,688 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
How reliable is IAD to SFO compared with the rest of the country?
77.5% of flights arrive on time here against a national 77.3%, a difference of half a point in its favour. That is worth a B+ on this site's grading scale.
What time of day has the fewest delays on IAD to SFO?
The 5am–8am departure window is the strongest at 85.0% on time. The 5pm–8pm window is the weakest at 62.8%, 22 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are June delays on IAD to SFO?
June is the weakest month at 63.5% on time, compared with 87.8% in March. Across the year that is 24 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
- SFO to IAD — the return legseparate record
- Washington Dulles International (IAD) delay statistics
- San Francisco International (SFO) delay statistics
- IAD to ATL, a related route78.0%
- LAX to SFO, a related route60.1%
- IAD to DEN, a related route83.1%
- United Airlines on-time record77.5%
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. IAD to SFO and SFO to IAD 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.