Flight number record

AS 538

Alaska Airlines · Seattle to Chicago

Route: SEA → ORD
Departs: 17:55
Flights: 350
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s AS 538, check with Alaska Airlines.

AS 538 lands a B+, about a point 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 350 flights, with a median arrival 7 minutes early.

On time

78.4%

Arrivals under 15 minutes late, of 343 completed flights

Avg delay

67 min

Across delayed arrivals only, not all flights

Cancelled

0.86%

National rate is 1.81%

1 hour+ late

7.0%

National rate is 8.1%

These figures cover 350 flights between July 2025 and June 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.

Schedule

When AS 538 flies

AS 538 flies SEA to ORD without a single fixed slot. Its most common scheduled departure was 17:55, used on 78 of 350 flights, with 17:49 (64 flights) and 17:50 (56 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 17:5578 flights22.3%
Departs 17:4964 flights18.3%
Departs 17:5056 flights16.0%

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 17:55 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and AS 538 runs 10 points better at 78.4%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.

Against the route

AS 538 next to SEA to ORD

Every carrier on SEA to ORD combined arrived on time 75.0% of the time across 5,566 flights, so AS 538 is 3 points ahead of it. Alaska flew 1,794 flights on the same city pair under all its flight numbers, including this one, and those ran 72.3% on time. Across its whole network Alaska Airlines managed 79.1%, close to this flight's figure.

AS 538 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
AS 538thin sample	350	78.4%	67 min	0.86%	B+
All Alaska Airlines on SEA–ORD	1,794	72.3%	55 min	1.06%	C
All carriers on SEA–ORD	5,566	75.0%	74 min	1.28%	B
Alaska Airlines, whole network	293,372	79.1%	52 min	1.28%	B

Across the year

AS 538 quarter by quarter

AS 538 did not run the same all year. Its best quarter was Jan–Mar 2026 at 86.4% on time and its weakest Jul–Sep 2025 at 58.9%, a swing of 28 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 202591 flights58.9%
Oct–Dec 202578 flights84.0%
Jan–Mar 202690 flights86.4%
Apr–Jun 202691 flights85.6%

Scale runs 50% to 90%. Rows with fewer than 30 flights show a dash.

By weekday, AS 538 did best on Tuesday at 87.5% on time and worst on Thursday at 70.8%. Each day rests on about 50 flights, so a gap of 17 points is worth noticing but could still narrow in another year.

Delay causes

Why AS 538 runs late

One category carries most of the weight here. National Airspace System accounts for 46% of the 4,963 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.

National Airspace System
46%
Carrier
30%
Late-arriving aircraft
24%
Extreme weather
1%

46% 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 2,262 minutes out of 4,963, against a national NAS share of 21%. The split is drawn from 4,963 delay minutes reported on AS 538.

Cancellations are rare at 0.86%, 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

7.0% 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 about an hour, which a normal layover absorbs.

At 1,721 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.

Every one of the 350 flights under AS 538 in the data flew SEA to ORD. The number was not reused on any other city pair, which makes this a clean record of one route.

One caution: this is a thin sample. 350 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 AS 538

For a booking, read AS 538 as 78.4% on time with 0.86% cancelled over 350 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 Alaska 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.

Key figures