Carrier route record
UAIAD→PHX
United Airlines · Washington to Phoenix
- Flights
- 704
- Period
- September 2025 to August 2026
- Share of route
- 72%
- 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 PHX earns an 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 8 points better than the national rate of 77.3%. When something does go wrong the average delay runs about an hour. That rests on 704 flights, with a median arrival 11 minutes early.
Set against the rest of the country, United's IAD to PHX record is 8 points better than the US average of 77.3%. That gap is worth roughly 79 fewer late arrivals for every thousand flights.
Key figures
On time
85.2%
Arrivals under 15 minutes late, of 697 completed flights
Avg delay
66 min
Across delayed arrivals only, not all flights
Cancelled
0.85%
National rate is 1.89%
Whole route
81.2%
Every carrier on IAD to PHX, 979 flights
These figures cover 704 flights between September 2025 and August 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.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Carrier by carrier
United against every carrier on IAD to PHX
United flew 704 of the 979 flights on IAD to PHX, most of the route. Its 85.2% on time is 4 points better than the route as a whole, which runs 81.2%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from United at 85.2% to Southwest at 71.0%. 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) | 704 | 85.2% | 66 min | 0.85% | A+ |
| Southwest Airlinesthin sample | 275 | 71.0% | 45 min | 0.73% | C+ |
Flight by flight
United flight numbers on IAD to PHX
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 17 points, against half a point between the best and worst carrier.
- 5am–8am—
- 8am–11am150 flights96.6%
- 11am–2pm193 flights87.4%
- 2pm–5pm—
- 5pm–8pm361 flights79.3%
- 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 96.6% of the time, against 79.3% for the evening window. That is 17 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 361 flights scheduled in it.
Across the year
United on IAD to PHX through the year
June is the worst month at 70.0% on time, 25 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 91.5% on time and Friday the weakest at 82.7%, a spread of 9 points.
Arrival by arrival
How late United on IAD to PHX runs when it is late
United on IAD to PHX often beats the schedule: 297 of 697 completed flights, 43%, arrived 15 minutes or more early. The 103 late arrivals split 41 under half an hour, 31 between 30 and 60 minutes, and 31 an hour or more.
- 15+ min early297 flights42.6%
- Within 15 min297 flights42.6%
- 15–29 min late41 flights5.9%
- 30–59 min late31 flights4.4%
- 1–2 hours late15 flights2.2%
- 2+ hours late16 flights2.3%
Scale runs 0% to 100%.
Share of 697 completed flights by arrival against schedule.
25 of 87 late departures made up the time and arrived on time, 29% of them. In the other direction, 41 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 PHX.
The worst days
Worst days for United on IAD to PHX
The latest arrival of the period was on 5 July 2026, 6 hours 3 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 5 July 2026 | 6 hours 3 minutes | National Airspace System |
| 15 March 2026 | 5 hours 32 minutes | National Airspace System |
| 26 January 2026 | 5 hours 28 minutes | Late-arriving aircraft |
| 5 November 2025 | 4 hours 46 minutes | National Airspace System |
| 22 February 2026 | 4 hours 29 minutes | Carrier |
Delay causes
Why United runs late on this route
National Airspace System accounts for 46% of the 6,832 delay minutes carriers reported here, and the remaining four split what is left.
- 46%National Airspace System
- 27%Late-arriving aircraft
- 24%Carrier
- 3%Extreme weather
46% 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 3,160 minutes out of 6,832, against a national NAS share of 21%. The split is drawn from 6,832 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.
Connections and stage length
What a delay here costs
Badly late arrivals are rare here: only 4.4% 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 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 90.8% on time across 704 flights, 6 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 6 points of difference.
One caution: this is a thin sample. 704 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. 704 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 85.2% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 697 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 PHX71.0%
- United Airlines network-wide record
- Washington Dulles International (IAD) delay statistics
- Phoenix Sky Harbor International (PHX) delay statistics
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
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.