Flight number record

AS 538

Alaska Airlines · Seattle to Chicago

Route: SEA → ORD
Departs: 17:48
Flights: 350
Period: September 2025 to August 2026

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

AS 538 lands a B+, 5 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 350 flights, with a median arrival 10 minutes early.

Set against the rest of the country, AS 538's record is 5 points better than the US average of 77.3%. That gap is worth roughly 52 fewer late arrivals for every thousand flights.

On time

82.5%

Arrivals under 15 minutes late, of 343 completed flights

Avg delay

64 min

Across delayed arrivals only, not all flights

Cancelled

0.57%

National rate is 1.89%

1 hour+ late

5.5%

National rate is 8.3%

These figures cover 350 flights between September 2025 and August 2026. The median arrival is 10 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.

Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.

Schedule

When AS 538 flies

AS 538 flies SEA to ORD without a single fixed slot. Its most common scheduled departure was 17:48, used on 69 of 350 flights, with 17:55 (66 flights) and 17:49 (64 flights) next.

Departs 17:4869 flights19.7%
Departs 17:5566 flights18.9%
Departs 17:4964 flights18.3%

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 17:48 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.0%, and AS 538 runs 15 points better at 82.5%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.

Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.

Against the route

AS 538 next to SEA to ORD

Every carrier on SEA to ORD combined arrived on time 76.7% of the time across 5,538 flights, so AS 538 is 6 points ahead of it. Alaska flew 1,775 flights on the same city pair under all its flight numbers, including this one, and those ran 73.8% on time. Across its whole network Alaska Airlines managed 79.7%, which this flight beats by 3 points.

AS 538 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
AS 538thin sample	350	82.5%	64 min	0.57%	B+
All Alaska Airlines on SEA–ORD	1,775	73.8%	59 min	1.13%	C
All carriers on SEA–ORD	5,538	76.7%	79 min	1.17%	B
Alaska Airlines, whole network	309,844	79.7%	52 min	1.20%	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 2026 at 73.3%, a swing of 13 points on roughly 70 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 flights76.7%
Oct–Dec 202578 flights84.0%
Jan–Mar 202690 flights86.4%
Apr–Jun 202691 flights85.6%
Jul–Sep 202661 flights73.3%

Scale runs 65% to 90%.

By weekday, AS 538 did best on Tuesday at 93.6% on time and worst on Sunday at 76.5%. Each day rests on about 50 flights, so a gap of 17 points is worth noticing but could still narrow in another year.

Arrival by arrival

How late AS 538 runs when it is late

AS 538 often beats the schedule: 145 of 343 completed flights, 42%, arrived 15 minutes or more early. The 60 late arrivals split 21 under half an hour, 20 between 30 and 60 minutes, and 19 an hour or more.

15+ min early145 flights42.3%
Within 15 min138 flights40.2%
15–29 min late21 flights6.1%
30–59 min late20 flights5.8%
1–2 hours late13 flights3.8%
2+ hours late6 flights1.7%

Scale runs 0% to 100%.

Share of 343 completed flights by arrival against schedule.

A late pushback is often recovered here: of 85 departures that left 15 minutes late or more, 35 still arrived on time. 10 flights left on time and still arrived late.

The worst days

Worst days for AS 538

The latest arrival of the period was on 8 June 2026, 5 hours 9 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. The same cause led on three of the five worst days.

The latest arrivals of AS 538 in the period
Date	Arrived late by	Largest filed cause
8 June 2026	5 hours 9 minutes	National Airspace System
10 June 2026	4 hours 57 minutes	National Airspace System
11 January 2026	4 hours 55 minutes	Carrier
6 January 2026	2 hours 47 minutes	Late-arriving aircraft
26 March 2026	2 hours 40 minutes	National Airspace System

Delay causes

Why AS 538 runs late

National Airspace System accounts for 53% of the 3,839 delay minutes carriers reported here, and the remaining four split what is left.

National Airspace System
53%
Carrier
27%
Late-arriving aircraft
16%
Extreme weather
4%

53% 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 2,048 minutes out of 3,839, against a national NAS share of 21%. The split is drawn from 3,839 delay minutes reported on AS 538.

Cancellations are rare at 0.57%, 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

5.5% 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 1,721 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 82.5% on time with 0.57% 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, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures