Flight number record
UA 2331
United Airlines · Washington to Chicago
- Route
- IAD → ORD
- Departs
- 13:15
- Flights
- 365
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 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 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That is a workable record, not a spotless one. That rests on 365 flights, with a median arrival 6 minutes early.
Key figures
On time
80.3%
Arrivals under 15 minutes late, of 361 completed flights
Avg delay
96 min
Across delayed arrivals only, not all flights
Cancelled
0.82%
National rate is 1.81%
1 hour+ late
8.0%
National rate is 8.1%
These figures cover 365 flights between July 2025 and June 2026. Beyond the headline rate, 8.0% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
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 91 of 365 flights, with 13:20 (83 flights) and 13:10 (69 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 13:1591 flights24.9%
- Departs 13:2083 flights22.7%
- Departs 13:1069 flights18.9%
Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.
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 78.8%, and UA 2331 runs level with that at 80.3%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
Against the route
UA 2331 next to IAD to ORD
Every carrier on IAD to ORD combined arrived on time 75.2% of the time across 2,054 flights, so UA 2331 is 5 points ahead of it. Across its whole network United Airlines managed 79.0%, close to this flight's figure.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 2331 | 365 | 80.3% | 96 min | 0.82% | B+ |
| All United Airlines on IAD–ORD | 2,054 | 75.2% | 73 min | 0.83% | B+ |
| All carriers on IAD–ORD | 2,054 | 75.2% | 73 min | 0.83% | B+ |
| United Airlines, whole network | 821,041 | 79.0% | 72 min | 1.01% | B |
Across the year
UA 2331 quarter by quarter
Quarter by quarter UA 2331 held fairly steady: 74.4% in Jul–Sep 2025, 83.5% in Oct–Dec 2025, 83.1% in Jan–Mar 2026 and 80.2% in Apr–Jun 2026. A spread of 9 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Jul–Sep 202592 flights74.4%
- Oct–Dec 202592 flights83.5%
- Jan–Mar 202690 flights83.1%
- Apr–Jun 202691 flights80.2%
Scale runs 65% to 90%. Rows with fewer than 30 flights show a dash.
By weekday, UA 2331 ranged from 76.5% on Sunday to 88.2% on Tuesday. With about 52 flights behind each day, a spread of 12 points is inside normal variation, so the day you fly is not worth changing for this flight.
Delay causes
Why UA 2331 runs late
One category carries most of the weight here. National Airspace System accounts for 49% of the 6,787 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 49%National Airspace System
- 26%Carrier
- 23%Late-arriving aircraft
- 2%Extreme weather
49% 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 3,301 minutes out of 6,787, against a national NAS share of 21%. The split is drawn from 6,787 delay minutes reported on UA 2331.
Cancellations are rare at 0.82%, 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 routes
What a delay on this flight costs
8.0% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last an hour and a half, which a normal layover absorbs.
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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
UA 2331 is not only a IAD to ORD flight. It also flew TPA to IAD (318 flights, 93.0% 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 | 93.0% | 53 min | 0.94% | A+ |
What to do with this
Booking UA 2331
For a booking, read UA 2331 as 80.3% 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 route47.9%
- United Airlines 1738 on the same route79.4%
- United Airlines 1775 on the same route83.5%
- 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
- Connecting flights: how much buffer the data says you need
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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.