Flight number record
UA 1831
United Airlines · Atlanta to Washington
- Route
- ATL → IAD
- Departs
- 14:40
- Flights
- 361
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s UA 1831, check with United Airlines.
UA 1831 lands a B+, about a point worse than the national rate of 77.3%. About one flight in four arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That rests on 361 flights, with a median arrival 4 minutes early.
Key figures
On time
76.2%
Arrivals under 15 minutes late, of 357 completed flights
Avg delay
97 min
Across delayed arrivals only, not all flights
Cancelled
0.83%
National rate is 1.89%
1 hour+ late
12.0%
National rate is 8.3%
These figures cover 361 flights between September 2025 and August 2026. Beyond the headline rate, 12.0% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When UA 1831 flies
UA 1831 flies ATL to IAD without a single fixed slot. Its most common scheduled departure was 14:40, used on 108 of 361 flights, with 14:41 (82 flights) and 14:37 (68 flights) next.
- Departs 14:40108 flights29.9%
- Departs 14:4182 flights22.7%
- Departs 14:3768 flights18.8%
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 14:40 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 71.9%, and UA 1831 runs 4 points better at 76.2%. 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 1831 next to ATL to IAD
Every carrier on ATL to IAD combined arrived on time 76.4% of the time across 4,005 flights, so UA 1831 is about level with it. United flew 1,091 flights on the same city pair under all its flight numbers, including this one, and those ran 81.6% on time. Across its whole network United Airlines managed 78.8%, which this flight trails by 3 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 1831thin sample | 361 | 76.2% | 97 min | 0.83% | B+ |
| All United Airlines on ATL–IAD | 1,091 | 81.6% | 78 min | 0.92% | B+ |
| All carriers on ATL–IAD | 4,005 | 76.4% | 79 min | 2.12% | B |
| United Airlines, whole network | 830,825 | 78.8% | 73 min | 1.02% | B |
Across the year
UA 1831 quarter by quarter
UA 1831 did not run the same all year. Its best quarter was Apr–Jun 2026 at 84.6% on time and its weakest Jul–Sep 2026 at 64.4%, a swing of 20 points on roughly 72 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 flights70.0%
- Oct–Dec 202590 flights73.3%
- Jan–Mar 202689 flights80.5%
- Apr–Jun 202691 flights84.6%
- Jul–Sep 202661 flights64.4%
Scale runs 55% to 90%.
By weekday, UA 1831 did best on Tuesday at 84.3% on time and worst on Sunday at 66.7%. Each day rests on about 52 flights, so a gap of 18 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late UA 1831 runs when it is late
When UA 1831 is late it tends to be very late: 43 of its 85 late arrivals were an hour or more behind, and 19 were two hours or more.
- 15+ min early59 flights16.5%
- Within 15 min213 flights59.7%
- 15–29 min late18 flights5.0%
- 30–59 min late24 flights6.7%
- 1–2 hours late24 flights6.7%
- 2+ hours late19 flights5.3%
Scale runs 0% to 100%.
Share of 357 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 78 departures that left 15 minutes late or more, only 8 made it up before arrival. 15 flights left on time and still arrived late.
The worst days
Worst days for UA 1831
The latest arrival of the period was on 18 June 2026, 16 hours 2 minutes behind schedule; most of its delay minutes were filed as extreme weather. On three of the five worst days the largest share was filed as a late-arriving aircraft.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 18 June 2026 | 16 hours 2 minutes | Extreme weather |
| 25 September 2025 | 6 hours 39 minutes | Late-arriving aircraft |
| 18 May 2026 | 5 hours 4 minutes | Late-arriving aircraft |
| 18 July 2026 | 4 hours 52 minutes | National Airspace System |
| 15 June 2026 | 4 hours 49 minutes | Late-arriving aircraft |
Delay causes
Why UA 1831 runs late
Late-arriving aircraft accounts for 47% of the 8,232 delay minutes carriers reported here, and the remaining four split what is left.
- 47%Late-arriving aircraft
- 29%National Airspace System
- 12%Carrier
- 12%Extreme weather
Extreme weather accounts for 12% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the quarterly figures above are the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.0 times the usual weather exposure. The split is drawn from 8,232 delay minutes reported on UA 1831.
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
12.0% 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 534 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.
The same number turns up on three other city pairs in the data, including IAD to EWR (210), ORD to ATL (21) and PBI to EWR (3), but none flew often enough under UA 1831 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to ATL to IAD 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 1831
For a booking, UA 1831 is a flight to put a long connection behind. 12.0% of its completed flights arrived an hour or more late, which a short layover will not absorb. If the onward flight is on a separate ticket, the risk sits with you.
Related
Where to go next
- ATL to IAD, every carrier and departure
- IAD to ATL, the return direction
- Delta Air Lines 1695 on the same route75.6%
- Delta Air Lines 2549 on the same route72.8%
- United Airlines 632 on the same route87.0%
- United Airlines 2634 on the same route76.6%
- Delta Air Lines 1309 on the same route72.6%
- Delta Air Lines 1444 on the same route87.6%
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Washington Dulles International (IAD) 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
- Why the first flight of the morning is statistically safest
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.