Carrier route record
UAIAD→PHX
United Airlines · Washington to Phoenix
- Flights
- 760
- Period
- July 2025 to June 2026
- Share of route
- 69%
- Carriers
- 2
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on IAD to PHX 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 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 760 flights, with a median arrival 10 minutes early.
Set against the rest of the country, United's IAD to PHX record is 7 points better than the US average of 77.6%. That gap is worth roughly 73 fewer late arrivals for every thousand flights.
Key figures
On time
84.9%
Arrivals under 15 minutes late, of 754 completed flights
Avg delay
77 min
Across delayed arrivals only, not all flights
Cancelled
0.79%
National rate is 1.81%
Whole route
79.9%
Every carrier on IAD to PHX, 1,097 flights
These figures cover 760 flights between July 2025 and June 2026. The median arrival is 10 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
United against every carrier on IAD to PHX
United flew 760 of the 1,097 flights on IAD to PHX, most of the route. Its 84.9% on time is 5 points better than the route as a whole, which runs 79.9%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from United at 84.9% to Southwest at 68.7%. 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) | 760 | 84.9% | 77 min | 0.79% | B+ |
| Southwest Airlinesthin sample | 337 | 68.7% | 48 min | 0.89% | C+ |
Flight by flight
United flight numbers on IAD to PHX
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 19 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–8am—
- 8am–11am199 flights95.9%
- 11am–2pm201 flights87.4%
- 2pm–5pm—
- 5pm–8pm360 flights77.4%
- 8pm–5am—
Scale runs 70% to 100%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 95.9% of the time, against 77.4% 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 5pm–8pm window is the busiest, with 360 flights scheduled in it.
Across the year
United on IAD to PHX through the year
July is the worst month at 66.7% on time, 28 points below April, the best at 95.1%. 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. March was the busiest month here, with 86 flights.
Across the week, Tuesday is the strongest day at 90.2% on time and Wednesday the weakest at 80.6%. 10 points is a smaller lever than departure hour, but it is free.
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 8,770 reported delay minutes.
- 35%Late-arriving aircraft
- 32%National Airspace System
- 26%Carrier
- 8%Extreme weather
35% 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 8,770 reported delay minutes here, that single category outweighs weather by 4 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 8,770 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 95.9% on time here.
Cancellations are rare at 0.79%, 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 costs
Badly late arrivals are rare here: only 4.9% 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 1,956 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 89.7% on time across 761 flights, 5 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 5 points of difference.
One caution: this is a thin sample. 760 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking United on IAD to PHX
Put together: treat all of this as provisional. 760 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 84.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 754 completed flights over 12 months sit behind that.
Related
Where to go next
- IAD to PHX, every carrier
- United on PHX to IAD, the return leg
- Southwest Airlines on IAD to PHX68.7%
- United Airlines network-wide record
- Washington Dulles International (IAD) delay statistics
- Phoenix Sky Harbor International (PHX) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.