Flight number record
DL 831
Delta Air Lines · Seattle to Austin
- Route
- SEA → AUS
- Departs
- 11:35
- Flights
- 353
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 831, check with Delta Air Lines.
DL 831 lands a B, about a point 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 353 flights, with a median arrival 7 minutes early.
Key figures
On time
78.7%
Arrivals under 15 minutes late, of 347 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
1.70%
National rate is 1.89%
1 hour+ late
6.9%
National rate is 8.3%
These figures cover 353 flights between September 2025 and August 2026. The median arrival is 7 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 DL 831 flies
DL 831 flies SEA to AUS without a single fixed slot. Its most common scheduled departure was 11:35, used on 71 of 353 flights, with 09:35 (61 flights) next.
- Departs 11:3571 flights20.1%
- Departs 09:3561 flights17.3%
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 11:35 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and DL 831 runs level with that at 78.7%. 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
DL 831 next to SEA to AUS
Every carrier on SEA to AUS combined arrived on time 78.5% of the time across 2,090 flights, so DL 831 is about level with it. Delta flew 950 flights on the same city pair under all its flight numbers, including this one, and those ran 80.1% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight trails by 2 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 831thin sample | 353 | 78.7% | 64 min | 1.70% | B |
| All Delta Air Lines on SEA–AUS | 950 | 80.1% | 67 min | 1.05% | B |
| All carriers on SEA–AUS | 2,090 | 78.5% | 55 min | 0.81% | B+ |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 831 quarter by quarter
DL 831 did not run the same all year. Its best quarter was Jan–Mar 2026 at 88.1% on time and its weakest Jul–Sep 2026 at 67.7%, a swing of 20 points on roughly 88 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 flights—
- Oct–Dec 202588 flights75.9%
- Jan–Mar 202687 flights88.1%
- Apr–Jun 202686 flights77.6%
- Jul–Sep 202662 flights67.7%
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
By weekday, DL 831 did best on Tuesday at 92.3% on time and worst on Friday at 65.4%. Each day rests on about 50 flights, so a gap of 27 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 831 runs when it is late
DL 831 often beats the schedule: 116 of 347 completed flights, 33%, arrived 15 minutes or more early. The 74 late arrivals split 33 under half an hour, 17 between 30 and 60 minutes, and 24 an hour or more.
- 15+ min early116 flights33.4%
- Within 15 min157 flights45.2%
- 15–29 min late33 flights9.5%
- 30–59 min late17 flights4.9%
- 1–2 hours late12 flights3.5%
- 2+ hours late12 flights3.5%
Scale runs 0% to 100%.
Share of 347 completed flights by arrival against schedule.
A late pushback is often recovered here: of 71 departures that left 15 minutes late or more, 24 still arrived on time. In the other direction, 27 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 AUS.
The worst days
Worst days for DL 831
The latest arrival of the period was on 13 March 2026, 4 hours 37 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 carrier-caused (crew, maintenance, fuelling, baggage).
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 13 March 2026 | 4 hours 37 minutes | Extreme weather |
| 8 November 2025 | 4 hours 26 minutes | Carrier |
| 27 July 2026 | 3 hours 57 minutes | Carrier |
| 12 December 2025 | 3 hours 48 minutes | Late-arriving aircraft |
| 23 October 2025 | 3 hours 21 minutes | Carrier |
Delay causes
Why DL 831 runs late
Carrier accounts for 46% of the 4,719 delay minutes carriers reported here, and the remaining four split what is left.
- 46%Carrier
- 24%National Airspace System
- 23%Late-arriving aircraft
- 7%Extreme weather
The largest share of delay minutes, 46%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,152 of the 4,719 delay minutes reported here. The split is drawn from 4,719 delay minutes reported on DL 831.
Cancellations sit at 1.70% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
6.9% 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 1,770 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 one other city pair in the data, including AUS to SEA (231), but none flew often enough under DL 831 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to SEA to AUS only.
One caution: this is a thin sample. 353 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 DL 831
For a booking, read DL 831 as 78.7% on time with 1.70% cancelled over 353 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- SEA to AUS, every carrier and departure
- AUS to SEA, the return direction
- Delta Air Lines 848 on the same route73.5%
- Alaska Airlines 502 on the same route83.1%
- Alaska Airlines 352 on the same route84.3%
- Delta Air Lines 739 on the same route89.2%
- Alaska Airlines 372 on the same route77.6%
- Seattle-Tacoma International (SEA) delay statistics
- Austin-Bergstrom International (AUS) delay statistics
- Delta Air Lines on-time record
- Every Delta Air Lines flight number with a record
- The most and least reliable flight numbers in the US
- The best time of day to fly, according to 7.05 million flight records
A flight number here means Delta Air Lines’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.