Route reliability record
SFO→IAD
San Francisco to Washington
- Flights
- 2,788
- Period
- July 2025 to June 2026
- Distance
- 2,418 mi
- Carriers
- 2
This route lands a B+, 5 points better than the national rate of 77.6%. About one flight in six arrive 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 2,788 flights, with a median arrival 9 minutes early.
Set against the rest of the country, this route's record is 5 points better than the US average of 77.6%. That gap is worth roughly 49 fewer late arrivals for every thousand flights.
Key figures
On time
82.5%
Arrivals under 15 minutes late, of 2,765 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
0.75%
National rate is 1.81%
Best carrier
United
83.8% on time across 2,690 flights
These figures cover 2,788 flights between July 2025 and June 2026. The median arrival is 9 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
Which airline is most reliable on SFO 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 | 2,690 | 83.8% | 64 min | 0.74% | B+ |
| Alaska Airlinesthin sample | 98 | 46.4% | 60 min | 1.02% | F |
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 24 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am137 flights97.8%
- 8am–11am576 flights81.3%
- 11am–2pm569 flights74.3%
- 2pm–5pm260 flights84.5%
- 5pm–8pm128 flights85.2%
- 8pm–5am1,118 flights84.6%
Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 74.3% on time against 97.8% for 5am–8am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 8pm–5am window is the busiest, with 1,118 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 27 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 65.2% on time, 27 points below February, the best at 92.1%. 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.
The day of the week is close to irrelevant here: 4 points separates the best day from the worst. Weekly demand peaks are not what drives the delays on this operation.
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 31,000 reported delay minutes.
- 41%Carrier
- 40%Late-arriving aircraft
- 18%National Airspace System
- 1%Extreme weather
- 0%Security
40% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 31,000 reported delay minutes here, that single category outweighs weather by 40 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 30,913 reported delay minutes.
The largest share of delay minutes, 41%, 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 13,000 of the 31,000 delay minutes reported here.
Cancellations are rare at 0.75%, 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 actually costs
6.0% 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 are the about an hour kind, 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 78.2% on time across 2,787 flights, 4 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 4 points of difference.
The sample behind these figures is 2,788 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.
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 92.1% on time and July 65.2%, a swing of 27 points. If the dates move at all, move them out of July before you think about anything else. 2,765 completed flights over 12 months sit behind that.
Common questions
SFO to IAD questions
How often is SFO to IAD delayed?
About one flight in six arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 17.5% of the 2,788 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
How reliable is SFO to IAD compared with the rest of the country?
82.5% of flights arrive on time here against a national 77.6%, a difference of 5 points in its favour. That is worth a B+ on this site's grading scale.
What time of day has the fewest delays on SFO to IAD?
The 5am–8am departure window is the strongest at 97.8% on time. The 11am–2pm window is the weakest at 74.3%, 24 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 July delays on SFO to IAD?
July is the weakest month at 65.2% on time, compared with 92.1% in February. Across the year that is 27 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 SFO — the return legseparate record
- San Francisco International (SFO) delay statistics
- Washington Dulles International (IAD) delay statistics
- United Airlines on-time record83.8%
- Alaska Airlines on-time record46.4%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. SFO to IAD and IAD to SFO are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.