Flight number record

AS 439

Alaska Airlines · Houston to Seattle

Route: IAH → SEA
Departs: 19:10
Flights: 361
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s AS 439, check with Alaska Airlines.

AS 439 draws a C+. About one flight in three arrives at least 15 minutes late, and the typical late arrival is about 50 minutes behind schedule. Build slack into anything you connect to. That rests on 361 flights, with a median arrival right on schedule.

The national on-time rate over the same period is 77.6%, so AS 439 runs 10 points behind the country as a whole. Across a thousand flights that is about 102 extra late arrivals.

On time

67.4%

Arrivals under 15 minutes late, of 359 completed flights

Avg delay

51 min

Across delayed arrivals only, not all flights

Cancelled

0.28%

National rate is 1.81%

1 hour+ late

7.5%

National rate is 8.1%

These figures cover 361 flights between July 2025 and June 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.

Schedule

When AS 439 flies

AS 439 flies IAH to SEA without a single fixed slot. Its most common scheduled departure was 19:10, used on 71 of 361 flights, with 19:28 (50 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 19:1071 flights19.7%
Departs 19:2850 flights13.9%

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 19:10 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and AS 439 runs level with that at 67.4%. 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 439 next to IAH to SEA

Every carrier on IAH to SEA combined arrived on time 77.5% of the time across 2,095 flights, so AS 439 is 10 points behind it. Alaska flew 852 flights on the same city pair under all its flight numbers, including this one, and those ran 78.5% on time. Across its whole network Alaska Airlines managed 79.1%, which this flight trails by 12 points.

AS 439 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
AS 439thin sample	361	67.4%	51 min	0.28%	C+
All Alaska Airlines on IAH–SEA	852	78.5%	51 min	0.70%	B+
All carriers on IAH–SEA	2,095	77.5%	54 min	0.53%	B+
Alaska Airlines, whole network	293,372	79.1%	52 min	1.28%	B

Across the year

AS 439 quarter by quarter

AS 439 did not run the same all year. Its best quarter was Apr–Jun 2026 at 90.1% on time and its weakest Jul–Sep 2025 at 46.7%, a swing of 43 points on roughly 90 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 flights46.7%
Oct–Dec 202591 flights61.5%
Jan–Mar 202688 flights71.3%
Apr–Jun 202691 flights90.1%

Scale runs 40% to 95%. Rows with fewer than 30 flights show a dash.

By weekday, AS 439 did best on Thursday at 74.5% on time and worst on Saturday at 55.8%. Each day rests on about 52 flights, so a gap of 19 points is worth noticing but could still narrow in another year.

Delay causes

Why AS 439 runs late

One category carries most of the weight here. Late-arriving aircraft accounts for 53% of the 5,961 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.

Late-arriving aircraft
53%
National Airspace System
29%
Carrier
15%
Extreme weather
2%
Security
1%

53% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 5,961 reported delay minutes here, that single category outweighs weather by 23 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 5,961 delay minutes reported on AS 439.

Cancellations are rare at 0.28%, 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

7.5% 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 50 minutes, which a normal layover absorbs.

At 1,874 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 361 flights under AS 439 in the data flew IAH to SEA. 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. 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 AS 439

For a booking, AS 439 is one of the weaker ways to fly IAH to SEA: 10 points below the route as a whole. If the schedule allows, compare it with the other departures listed on the route page before settling on this one.

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