Route reliability record
LAX→IAD
Los Angeles to Washington
- Flights
- 2,454
- Period
- July 2025 to June 2026
- Distance
- 2,288 mi
- Carriers
- 3
This route earns a A+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 9 points better than the national rate of 77.6%. When something does go wrong the average delay runs about an hour. That rests on 2,454 flights, with a median arrival 11 minutes early.
Set against the rest of the country, this route's record is 9 points better than the US average of 77.6%. That gap is worth roughly 91 fewer late arrivals for every thousand flights.
Key figures
On time
86.7%
Arrivals under 15 minutes late, of 2,427 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
0.69%
National rate is 1.81%
Best carrier
United
87.2% on time across 2,319 flights
These figures cover 2,454 flights between July 2025 and June 2026. The median arrival is 11 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 LAX 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 | 2,319 | 87.2% | 57 min | 0.73% | A+ |
| Alaska Airlinesthin sample | 50 | 77.6% | 43 min | 0.00% | B+ |
| American Airlinesthin sample | 85 | 77.6% | 79 min | 0.00% | B+ |
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 26 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–8am78 flights94.7%
- 8am–11am736 flights83.7%
- 11am–2pm499 flights86.6%
- 2pm–5pm223 flights92.3%
- 5pm–8pm39 flights69.2%
- 8pm–5am879 flights87.7%
Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 94.7% of the time, against 69.2% for the evening window. That is 26 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 879 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 25 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 71.0% on time, 25 points below October, the best at 96.0%. 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. June was the busiest month here, with 253 flights.
Across the week, Tuesday is the strongest day at 90.0% on time and Saturday the weakest at 84.2%. 6 points is a smaller lever than departure hour, but it is free.
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 19,000 reported delay minutes.
- 40%Late-arriving aircraft
- 39%Carrier
- 20%National Airspace System
- 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 19,000 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 18,689 reported delay minutes.
The largest share of delay minutes, 39%, 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 7,362 of the 19,000 delay minutes reported here.
Cancellations are rare at 0.69%, 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
Badly late arrivals are rare here: only 4.2% 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 2,288 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 81.8% on time across 2,454 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 2,454 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. October runs 96.0% on time and July 71.0%, a swing of 25 points. If the dates move at all, move them out of July before you think about anything else. 2,427 completed flights over 12 months sit behind that.
Common questions
LAX to IAD questions
How often is LAX to IAD delayed?
About one flight in eight arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 13.3% of the 2,454 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
How reliable is LAX to IAD compared with the rest of the country?
86.7% of flights arrive on time here against a national 77.6%, a difference of 9 points in its favour. That is worth a A+ on this site's grading scale.
What time of day has the fewest delays on LAX to IAD?
The 5am–8am departure window is the strongest at 94.7% on time. The 5pm–8pm window is the weakest at 69.2%, 26 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 LAX to IAD?
July is the weakest month at 71.0% on time, compared with 96.0% in October. Across the year that is 25 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 LAX — the return legseparate record
- Los Angeles International (LAX) delay statistics
- Washington Dulles International (IAD) delay statistics
- United Airlines on-time record87.2%
- Alaska Airlines on-time record77.6%
- American Airlines on-time record77.6%
- 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. LAX to IAD and IAD to LAX 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.