Flight number record
UA 2331
United Airlines · Washington to Chicago
- Route
- IAD → ORD
- Departs
- 13:15
- Flights
- 365
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 2331, check with United Airlines.
UA 2331 lands a B+, 3 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 close to two hours on average. That rests on 365 flights, with a median arrival 6 minutes early.
Key figures
On time
79.8%
Arrivals under 15 minutes late, of 361 completed flights
Avg delay
112 min
Across delayed arrivals only, not all flights
Cancelled
0.82%
National rate is 1.89%
1 hour+ late
9.7%
National rate is 8.3%
These figures cover 365 flights between September 2025 and August 2026. Beyond the headline rate, 9.7% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When UA 2331 flies
UA 2331 flies IAD to ORD without a single fixed slot. Its most common scheduled departure was 13:15, used on 119 of 365 flights, with 13:10 (87 flights) and 12:40 (37 flights) next.
- Departs 13:15119 flights32.6%
- Departs 13:1087 flights23.8%
- Departs 12:4037 flights10.1%
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 13:15 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and UA 2331 runs level with that at 79.8%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
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Against the route
UA 2331 next to IAD to ORD
Every carrier on IAD to ORD combined arrived on time 74.7% of the time across 2,106 flights, so UA 2331 is 5 points ahead of it. 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 2331 | 365 | 79.8% | 112 min | 0.82% | B+ |
| All United Airlines on IAD–ORD | 2,106 | 74.7% | 79 min | 0.90% | C+ |
| All carriers on IAD–ORD | 2,106 | 74.7% | 79 min | 0.90% | C+ |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 2331 quarter by quarter
UA 2331 did not run the same all year. Its best quarter was Oct–Dec 2025 at 83.5% on time and its weakest Jul–Sep 2026 at 70.0%, a swing of 14 points on roughly 73 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202530 flights76.7%
- Oct–Dec 202592 flights83.5%
- Jan–Mar 202690 flights83.1%
- Apr–Jun 202691 flights80.2%
- Jul–Sep 202662 flights70.0%
Scale runs 60% to 90%.
By weekday, UA 2331 did best on Tuesday at 84.6% on time and worst on Sunday at 72.5%. Each day rests on about 52 flights, so a gap of 12 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 2331 runs when it is late
UA 2331 often beats the schedule: 102 of 361 completed flights, 28%, arrived 15 minutes or more early. The 73 late arrivals split 21 under half an hour, 17 between 30 and 60 minutes, and 35 an hour or more.
- 15+ min early102 flights28.3%
- Within 15 min186 flights51.5%
- 15–29 min late21 flights5.8%
- 30–59 min late17 flights4.7%
- 1–2 hours late16 flights4.4%
- 2+ hours late19 flights5.3%
Scale runs 0% to 100%.
Share of 361 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 52 departures that left 15 minutes late or more, only 4 made it up before arrival. In the other direction, 25 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 ORD.
The worst days
Worst days for UA 2331
The latest arrival of the period was on 11 June 2026, 16 hours 29 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). On three of the five worst days the largest share was filed as national airspace system delay.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 11 June 2026 | 16 hours 29 minutes | Carrier |
| 7 July 2026 | 8 hours 30 minutes | Late-arriving aircraft |
| 18 May 2026 | 7 hours 58 minutes | National Airspace System |
| 31 March 2026 | 7 hours 52 minutes | National Airspace System |
| 3 July 2026 | 5 hours 26 minutes | National Airspace System |
Delay causes
Why UA 2331 runs late
National Airspace System accounts for 55% of the 8,162 delay minutes carriers reported here, and the remaining four split what is left.
- 55%National Airspace System
- 23%Late-arriving aircraft
- 21%Carrier
- 1%Extreme weather
55% 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 4,501 minutes out of 8,162, against a national NAS share of 21%. The split is drawn from 8,162 delay minutes reported on UA 2331.
Cancellations are rare at 0.82%, 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
9.7% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
The 588 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
UA 2331 is not only a IAD to ORD flight. It also flew TPA to IAD (318 flights, 93.6% on time) often enough to be scored on its own. Airlines attach one number to several legs of an aircraft's day, and each leg keeps its own record here, so check which city pair is on your booking before reading a rate.
One caution: this is a thin sample. 365 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.
| Also flown as | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| TPA to IADthin sample | 318 | 93.6% | 54 min | 1.26% | A |
What to do with this
Booking UA 2331
For a booking, read UA 2331 as 79.8% on time with 0.82% cancelled over 365 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- IAD to ORD, every carrier and departure
- ORD to IAD, the return direction
- United Airlines 2497 on the same route46.5%
- United Airlines 1775 on the same route84.1%
- United Airlines 1738 on the same route78.2%
- Washington Dulles International (IAD) delay statistics
- Chicago O'Hare International (ORD) 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
- How often a connection fails at the major US hubs
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.