Carrier performance at one airport
UA→IAD
United Airlines at Washington Dulles International
- Departures
- 36,559
- Period
- July 2025 to June 2026
- Routes
- 25
- Rank here
- #2 of 10
United Airlines at Washington 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 a little over an hour on average. That is a workable record, not a spotless one. That rests on 36,559 flights, of which PSA Airlines flew 1,032 at 84.1% on time.
Measured against the airport rather than the country, United Airlines runs about a point ahead of the 81.1% weighted average across all carriers at IAD. That is the comparison worth making: every operator here works the same runways, the same airspace and the same weather.
Key figures
On time
82.3%
36,172 completed departures
Avg delay
73 min
Across delayed flights only
Cancelled
0.80%
At IAD, this carrier only
Rank here
#2
Of 10 carriers clearing the floor at IAD
These figures cover 37,000 flights between July 2025 and June 2026. The median arrival is 8 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.
Against the competition
Every carrier at IAD, ranked
The choice of carrier is not cosmetic here. PSA Airlines arrives on time 84.1% of the time; Frontier Airlines manages 69.7%. Sample sizes sit next to every figure, because a two-point gap across 1,631 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| PSA Airlines | 1,032 | 84.1% | 104 min | 3.39% | B− |
| United Airlines (this page) | 36,559 | 82.3% | 73 min | 0.80% | B+ |
| Republic Airways | 8,917 | 81.8% | 79 min | 2.69% | B |
| Delta Air Lines | 3,063 | 80.9% | 91 min | 2.45% | B |
| SkyWest Airlines | 2,440 | 79.0% | 139 min | 2.05% | B |
| American Airlines | 1,368 | 77.2% | 97 min | 2.70% | B |
| Southwest Airlines | 1,100 | 73.9% | 51 min | 1.09% | C |
| Allegiant Air | 567 | 73.4% | 120 min | 0.35% | C+ |
| Alaska Airlines | 1,344 | 71.7% | 55 min | 0.97% | C+ |
| Frontier Airlines | 1,631 | 69.7% | 99 min | 2.45% | C |
PSA Airlines cancels 3.4% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
Route by route
Where United Airlines flies from IAD
United Airlines operates 25 routes out of IAD with enough volume to report. Route records inside one carrier at one airport still spread widely, because a short shuttle and a transcontinental have very different exposure to a late inbound.
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| IAD to DEN · Denver | 2,798 | 83.2% | 71 min | 0.46% | B+ |
| IAD to SFO · San Francisco | 2,688 | 78.6% | 74 min | 0.89% | B+ |
| IAD to LAX · Los Angeles | 2,320 | 83.1% | 63 min | 0.99% | B+ |
| IAD to ORD · Chicago | 2,054 | 75.2% | 73 min | 0.83% | B+ |
| IAD to MCO · Orlando | 1,897 | 83.0% | 70 min | 0.58% | B+ |
| IAD to IAH · Houston | 1,869 | 83.7% | 68 min | 0.48% | B+ |
| IAD to EWR · Newark | 1,480 | 75.2% | 89 min | 2.23% | B |
| IAD to BOS · Boston | 1,459 | 77.4% | 73 min | 1.92% | B |
| IAD to TPA · Tampa | 1,180 | 82.2% | 67 min | 0.42% | B+ |
| IAD to ATL · Atlanta | 1,097 | 80.9% | 89 min | 0.46% | B+ |
| IAD to RDU · Raleigh | 1,080 | 85.1% | 70 min | 1.11% | A |
| IAD to SAN · San Diego | 1,040 | 87.1% | 65 min | 0.38% | A+ |
| IAD to LAS · Las Vegas | 1,009 | 86.8% | 70 min | 0.50% | A+ |
| IAD to AUS · Austin | 1,007 | 84.2% | 67 min | 0.79% | B+ |
| IAD to BNA · Nashville | 935 | 83.3% | 77 min | 0.75% | B+ |
| IAD to DFW · Dallas-Fort Worth | 914 | 79.8% | 82 min | 0.77% | B+ |
| IAD to BDL · Hartford | 892 | 86.2% | 58 min | 1.23% | A |
| IAD to PHX · Phoenix | 760 | 84.9% | 77 min | 0.79% | B+ |
| IAD to FLL · Fort Lauderdale | 719 | 84.4% | 67 min | 0.56% | B+ |
| IAD to CLE · Cleveland | 711 | 84.7% | 76 min | 0.56% | B+ |
| IAD to SEA · Seattle | 688 | 79.7% | 62 min | 0.58% | B+ |
| IAD to SAT · San Antonio | 641 | 85.6% | 92 min | 0.62% | A+ |
| IAD to MSY · New Orleans | 623 | 85.3% | 80 min | 0.48% | A+ |
| IAD to SJU · San Juan | 609 | 80.8% | 51 min | 0.49% | B+ |
| IAD to JAX · Jacksonville | 592 | 86.2% | 81 min | 0.68% | A+ |
Departure window
Best time of day for this operation
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 20 points, against 14 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1,652 flights92.1%
- 8am–11am10,722 flights89.3%
- 11am–2pm6,820 flights86.0%
- 2pm–5pm2,062 flights80.0%
- 5pm–8pm10,396 flights72.5%
- 8pm–5am4,907 flights80.2%
Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 92.1% of the time, against 72.5% for the evening window. That is 20 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 10,722 flights scheduled in it.
Across the year
Seasonal pattern
July is the worst month at 70.1% on time, 18 points below April, the best at 88.3%. 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 3,541 flights.
Delay causes
What holds this operation up
- 33%National Airspace System
- 32%Late-arriving aircraft
- 26%Carrier
- 8%Extreme weather
33% 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 155,000 minutes out of 464,000, against a national NAS share of 21%. The split is drawn from 464,320 reported delay minutes.
Cancellations are rare at 0.80%, 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.
6.4% 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 a little over an hour kind, which a normal layover absorbs.
36,559 flights sit behind these numbers, which is a large enough sample that the headline rate is not moving on noise. Where a sub-group falls below 30 flights the site shows a dash instead of a percentage.
Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 88.3% on time and July 70.1%, a swing of 18 points. If the dates move at all, move them out of July before you think about anything else. 36,172 completed flights over 12 months sit behind that.
Common questions
United Airlines at IAD
How often is United Airlines at 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 17.7% of the 36,559 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on United Airlines at IAD?
PSA Airlines leads at 84.1% on time across 1,032 flights. Frontier Airlines is at the other end on 69.7%, a gap of 14 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on United Airlines at IAD?
The 5am–8am departure window is the strongest at 92.1% on time. The 5pm–8pm window is the weakest at 72.5%, 20 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 United Airlines at IAD?
July is the weakest month at 70.1% on time, compared with 88.3% in April. Across the year that is 18 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
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.