Carrier performance at one airport

UA→IAD

United Airlines at Washington Dulles International

Departures: 36,915
Period: September 2025 to August 2026
Routes: 25
Rank here: #2 of 10

United Airlines at Washington lands a B+, 5 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That rests on 36,915 flights, of which PSA Airlines flew 967 at 83.8% on time.

Measured against the airport rather than the country, United Airlines runs about a point ahead of the 81.0% 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.

On time

82.1%

36,501 completed departures

Avg delay

73 min

Across delayed flights only

Cancelled

0.85%

At IAD, this carrier only

Rank here

Of 10 carriers clearing the floor at IAD

These figures cover 37,000 flights between September 2025 and August 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 83.8% of the time; Frontier Airlines manages 68.3%. Sample sizes sit next to every figure, because a two-point gap across 1,682 flights means less than a ten-point one.

On-time performance of all carriers departing IAD
Airline	Flights	On time	Avg delay	Cancelled	Grade
PSA Airlines	967	83.8%	114 min	3.21%	B−
United Airlines (this page)	36,915	82.1%	73 min	0.85%	B+
Republic Airways	8,421	81.5%	75 min	3.02%	B−
Delta Air Lines	3,159	80.4%	93 min	2.44%	B
SkyWest Airlines	2,514	79.5%	148 min	2.11%	B
American Airlines	1,505	77.5%	103 min	2.06%	B
Southwest Airlines	872	76.1%	47 min	0.92%	B+
Alaska Airlines	1,196	74.8%	51 min	1.09%	C
Allegiant Air	531	72.2%	106 min	0.94%	C+
Frontier Airlines	1,682	68.3%	95 min	2.79%	C

PSA Airlines cancels 3.2% 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.

United Airlines routes from IAD
Route	Flights	On time	Avg delay	Cancelled	Grade
IAD to DEN · Denver	2,791	84.1%	68 min	0.50%	B+
IAD to SFO · San Francisco	2,688	77.5%	72 min	0.71%	B+
IAD to LAX · Los Angeles	2,340	84.6%	61 min	0.77%	B+
IAD to ORD · Chicago	2,106	74.7%	79 min	0.90%	C+
IAD to MCO · Orlando	1,874	82.5%	69 min	0.91%	B+
IAD to IAH · Houston	1,862	84.7%	71 min	0.48%	B+
IAD to EWR · Newark	1,530	77.1%	98 min	2.61%	B
IAD to BOS · Boston	1,447	77.1%	70 min	2.07%	B
IAD to TPA · Tampa	1,109	83.6%	69 min	0.45%	B+
IAD to ATL · Atlanta	1,090	79.9%	78 min	0.73%	B+
IAD to RDU · Raleigh	1,078	83.3%	68 min	1.21%	B
IAD to SAN · San Diego	1,041	86.1%	65 min	0.67%	A+
IAD to AUS · Austin	987	84.5%	73 min	0.81%	B+
IAD to LAS · Las Vegas	965	88.0%	80 min	0.52%	A+
IAD to BDL · Hartford	941	85.8%	63 min	1.17%	A
IAD to DFW · Dallas-Fort Worth	928	80.0%	81 min	0.54%	B+
IAD to BNA · Nashville	927	81.3%	78 min	0.76%	B+
IAD to CLE · Cleveland	796	85.2%	80 min	0.38%	A+
IAD to PHX · Phoenix	704	85.2%	66 min	0.85%	A+
IAD to FLL · Fort Lauderdale	699	83.5%	71 min	0.57%	B+
IAD to SAT · San Antonio	644	84.7%	108 min	0.62%	B+
IAD to JAX · Jacksonville	643	83.8%	80 min	0.78%	B+
IAD to SJU · San Juan	636	78.3%	54 min	0.47%	B+
IAD to SEA · Seattle	625	81.3%	66 min	0.48%	B+
IAD to MSY · New Orleans	608	84.6%	82 min	0.49%	B+

Flight by flight

United Airlines flight numbers from IAD

57 United Airlines flight numbers leaving IAD flew their main route often enough to have a record of their own. Grouped by destination.

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 19 points, against 16 points between the best and worst carrier.

5am–8am1,668 flights91.4%
8am–11am10,689 flights89.2%
11am–2pm7,062 flights85.2%
2pm–5pm2,069 flights79.3%
5pm–8pm10,562 flights72.7%
8pm–5am4,865 flights80.0%

Scale runs 65% to 95%.

Book the early departure. Flights leaving between 5am–8am arrive on time 91.4% of the time, against 72.7% for the evening window. That is 19 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 10,689 flights scheduled in it.

Across the year

Seasonal pattern

Darker means more delays. Figures are on-time percentages.April best, July worst

July is the worst month at 73.4% on time, 15 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

National Airspace System
36%
Late-arriving aircraft
30%
Carrier
26%
Extreme weather
8%

36% 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 173,000 minutes out of 481,000, against a national NAS share of 21%. The split is drawn from 480,899 reported delay minutes.

Cancellations are rare at 0.85%, 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.

6.5% 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.

36,915 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 73.4%, a swing of 15 points. If the dates move at all, move them out of July before you think about anything else. 36,501 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 arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 17.9% of the 36,915 flights in this analysis, against 22.7% 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 83.8% on time across 967 flights. Frontier Airlines is at the other end on 68.3%, a gap of 16 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 91.4% on time. The 5pm–8pm window is the weakest at 72.7%, 19 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 73.4% on time, compared with 88.3% in April. Across the year that is 15 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures