Carrier route record
UAIAD→LAX
United Airlines · Washington to Los Angeles
- Flights
- 2,340
- Period
- September 2025 to August 2026
- Share of route
- 95%
- Carriers
- 2
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with United Airlines.
United on IAD to LAX earns a B+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.3%. When something does go wrong the average delay runs about an hour. That rests on 2,340 flights, with a median arrival 9 minutes early.
Set against the rest of the country, United's IAD to LAX record is 7 points better than the US average of 77.3%. That gap is worth roughly 73 fewer late arrivals for every thousand flights.
Key figures
On time
84.6%
Arrivals under 15 minutes late, of 2,319 completed flights
Avg delay
61 min
Across delayed arrivals only, not all flights
Cancelled
0.77%
National rate is 1.89%
Whole route
84.1%
Every carrier on IAD to LAX, 2,460 flights
These figures cover 2,340 flights between September 2025 and August 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.
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Carrier by carrier
United against every carrier on IAD to LAX
United flew 2,340 of the 2,460 flights on IAD to LAX, most of the route. Its 84.6% on time is about level with the route as a whole at 84.1%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from United at 84.6% to American at 75.0%. 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) | 2,340 | 84.6% | 61 min | 0.77% | B+ |
| American Airlinesthin sample | 120 | 75.0% | 53 min | 0.00% | B+ |
Flight by flight
United flight numbers on IAD to LAX
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Departure window
When United runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 16 points, against half a point between the best and worst carrier.
- 5am–8am233 flights92.3%
- 8am–11am414 flights88.5%
- 11am–2pm365 flights90.1%
- 2pm–5pm228 flights86.3%
- 5pm–8pm598 flights76.1%
- 8pm–5am502 flights83.2%
Scale runs 70% to 100%.
Book the early departure. Flights leaving between 5am–8am arrive on time 92.3% of the time, against 76.1% for the evening window. That is 16 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 598 flights scheduled in it.
Across the year
United on IAD to LAX through the year
January is the weak month at 77.0% on time, against 90.2% in September. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. June was the busiest month here, with 223 flights.
Across the week, Monday is the strongest day at 87.4% on time and Sunday the weakest at 81.4%, a spread of 6 points.
Arrival by arrival
How late United on IAD to LAX runs when it is late
United on IAD to LAX often beats the schedule: 885 of 2,319 completed flights, 38%, arrived 15 minutes or more early. The 357 late arrivals split 154 under half an hour, 95 between 30 and 60 minutes, and 108 an hour or more.
- 15+ min early885 flights38.2%
- Within 15 min1,077 flights46.4%
- 15–29 min late154 flights6.6%
- 30–59 min late95 flights4.1%
- 1–2 hours late65 flights2.8%
- 2+ hours late43 flights1.9%
Scale runs 0% to 100%.
Share of 2,319 completed flights by arrival against schedule.
A late pushback is often recovered here: of 350 departures that left 15 minutes late or more, 122 still arrived on time. In the other direction, 129 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at LAX.
The worst days
Worst days for United on IAD to LAX
The latest arrival of the period was on 30 January 2026, 11 hours 1 minute behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 30 January 2026 | 11 hours 1 minute | Late-arriving aircraft |
| 17 June 2026 | 10 hours 8 minutes | Late-arriving aircraft |
| 9 June 2026 | 7 hours 10 minutes | Late-arriving aircraft |
| 13 March 2026 | 5 hours 58 minutes | National Airspace System |
| 16 August 2026 | 5 hours 33 minutes | Carrier |
Delay causes
Why United runs late on this route
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 22,000 reported delay minutes.
- 33%Late-arriving aircraft
- 31%Carrier
- 26%National Airspace System
- 10%Extreme weather
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 92.3% on time here. The split is drawn from 21,619 reported delay minutes.
No single cause dominates. late-arriving aircraft at 33%, carrier at 31% and national airspace system at 26% split the 22,000 reported delay minutes between them. An even spread like this usually means the operation is running close to its designed capacity with no one obvious weak point, and it is the hardest pattern for a traveller to route around.
Cancellations are rare at 0.77%, 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 costs
Badly late arrivals are rare here: only 4.7% 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 2,288 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 88.0% on time across 2,341 flights, 3 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 3 points of difference.
The sample behind these figures is 2,340 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 United on IAD to LAX
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 90.2% on time and January 77.0%, a swing of 13 points. If the dates move at all, move them out of January before you think about anything else. 2,319 completed flights over 12 months sit behind that.
Related
Where to go next
- IAD to LAX, every carrier
- United on LAX to IAD, the return leg
- American Airlines on IAD to LAX75.0%
- United Airlines network-wide record
- Washington Dulles International (IAD) delay statistics
- Los Angeles International (LAX) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
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.