Flight number record

DL 831

Delta Air Lines · Seattle to Austin

Route: SEA → AUS
Departs: 11:35
Flights: 353
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 831, check with Delta Air Lines.

DL 831 lands a B, 2 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 about an hour on average. That is a workable record, not a spotless one. That rests on 353 flights, with a median arrival 8 minutes early.

On time

79.8%

Arrivals under 15 minutes late, of 347 completed flights

Avg delay

62 min

Across delayed arrivals only, not all flights

Cancelled

1.70%

National rate is 1.81%

1 hour+ late

6.6%

National rate is 8.1%

These figures cover 353 flights between July 2025 and June 2026. The median arrival is 8 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.

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) and 11:15 (56 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 11:3571 flights20.1%
Departs 09:3561 flights17.3%
Departs 11:1556 flights15.9%

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 11:35 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.8%, and DL 831 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.

Against the route

DL 831 next to SEA to AUS

Every carrier on SEA to AUS combined arrived on time 79.1% of the time across 2,059 flights, so DL 831 is about level with it. Delta flew 936 flights on the same city pair under all its flight numbers, including this one, and those ran 81.0% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 2 points.

DL 831 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 831thin sample	353	79.8%	62 min	1.70%	B
All Delta Air Lines on SEA–AUS	936	81.0%	72 min	1.28%	B
All carriers on SEA–AUS	2,059	79.1%	57 min	0.97%	B+
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	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 Oct–Dec 2025 at 75.9%, a swing of 12 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 202592 flights78.0%
Oct–Dec 202588 flights75.9%
Jan–Mar 202687 flights88.1%
Apr–Jun 202686 flights77.6%

Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.

By weekday, DL 831 did best on Tuesday at 94.3% on time and worst on Friday at 65.4%. Each day rests on about 50 flights, so a gap of 29 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 831 runs late

One category carries most of the weight here. Carrier accounts for 44% of the 4,367 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.

Carrier
44%
National Airspace System
26%
Late-arriving aircraft
25%
Extreme weather
5%

The largest share of delay minutes, 44%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 1,911 of the 4,367 delay minutes reported here. The split is drawn from 4,367 delay minutes reported on DL 831.

Cancellations sit at 1.70% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

Connections and routes

What a delay on this flight costs

6.6% 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 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 (177), 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 79.8% on time with 1.70% cancelled over 353 flights. Those are rates from the past twelve months, not a forecast for any particular day.

Where to go next

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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures