Flight number record
UA 1938
United Airlines · Washington to Phoenix
- Route
- IAD → PHX
- Departs
- 17:50
- Flights
- 361
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 1938, check with United Airlines.
UA 1938 lands a B+, 2 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 361 flights, with a median arrival 6 minutes early.
Key figures
On time
79.3%
Arrivals under 15 minutes late, of 357 completed flights
Avg delay
66 min
Across delayed arrivals only, not all flights
Cancelled
0.83%
National rate is 1.89%
1 hour+ late
6.7%
National rate is 8.3%
These figures cover 361 flights between September 2025 and August 2026. The median arrival is 6 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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Schedule
When UA 1938 flies
UA 1938 flies IAD to PHX without a single fixed slot. Its most common scheduled departure was 17:50, used on 82 of 361 flights, with 17:24 (37 flights) next.
- Departs 17:5082 flights22.7%
- Departs 17:2437 flights10.2%
Scale runs 0% to 100%.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 17:50 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.0%, and UA 1938 runs 11 points better at 79.3%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
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Against the route
UA 1938 next to IAD to PHX
Every carrier on IAD to PHX combined arrived on time 81.2% of the time across 979 flights, so UA 1938 is 2 points behind it. United flew 704 flights on the same city pair under all its flight numbers, including this one, and those ran 85.2% on time. Across its whole network United Airlines managed 78.8%, close to this flight's figure.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 1938thin sample | 361 | 79.3% | 66 min | 0.83% | B+ |
| All United Airlines on IAD–PHX | 704 | 85.2% | 66 min | 0.85% | A+ |
| All carriers on IAD–PHX | 979 | 81.2% | 57 min | 0.82% | B+ |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 1938 quarter by quarter
Quarter by quarter UA 1938 held fairly steady: 76.7% in Jul–Sep 2025, 77.3% in Oct–Dec 2025, 79.5% in Jan–Mar 2026, 84.6% in Apr–Jun 2026 and 75.0% in Jul–Sep 2026. A spread of 10 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Jul–Sep 202530 flights76.7%
- Oct–Dec 202588 flights77.3%
- Jan–Mar 202690 flights79.5%
- Apr–Jun 202691 flights84.6%
- Jul–Sep 202662 flights75.0%
Scale runs 65% to 90%.
By weekday, UA 1938 did best on Tuesday at 88.2% on time and worst on Saturday at 71.4%. Each day rests on about 52 flights, so a gap of 17 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 1938 runs when it is late
UA 1938 often beats the schedule: 118 of 357 completed flights, 33%, arrived 15 minutes or more early. The 74 late arrivals split 27 under half an hour, 23 between 30 and 60 minutes, and 24 an hour or more.
- 15+ min early118 flights33.1%
- Within 15 min165 flights46.2%
- 15–29 min late27 flights7.6%
- 30–59 min late23 flights6.4%
- 1–2 hours late13 flights3.6%
- 2+ hours late11 flights3.1%
Scale runs 0% to 100%.
Share of 357 completed flights by arrival against schedule.
15 of 63 late departures made up the time and arrived on time, 24% of them. In the other direction, 26 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 UA 1938
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 four 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 |
| 5 November 2025 | 4 hours 46 minutes | National Airspace System |
| 9 November 2025 | 4 hours 28 minutes | National Airspace System |
| 1 May 2026 | 3 hours 37 minutes | Late-arriving aircraft |
Delay causes
Why UA 1938 runs late
National Airspace System accounts for 56% of the 4,889 delay minutes carriers reported here, and the remaining four split what is left.
- 56%National Airspace System
- 22%Late-arriving aircraft
- 20%Carrier
- 2%Extreme weather
56% 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 2,714 minutes out of 4,889, against a national NAS share of 21%. The split is drawn from 4,889 delay minutes reported on UA 1938.
Cancellations are rare at 0.83%, 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 routes
What a delay on this flight costs
6.7% 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 about an hour, which a normal layover absorbs.
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 same number turns up on three other city pairs in the data, including JAX to IAD (225), ORD to JAX (44) and PHX to ORD (2), but none flew often enough under UA 1938 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to IAD to PHX only.
One caution: this is a thin sample. 361 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 UA 1938
For a booking, read UA 1938 as 79.3% on time with 0.83% cancelled over 361 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- IAD to PHX, every carrier and departure
- PHX to IAD, the return direction
- Washington Dulles International (IAD) delay statistics
- Phoenix Sky Harbor International (PHX) delay statistics
- United Airlines on-time record
- Every United Airlines flight number with a record
- The most and least reliable flight numbers in the US
- Worst months to fly in the US, ranked by the data
A flight number here means United Airlines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.
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.