Flight number record
AS 439
Alaska Airlines · Houston to Seattle
- Route
- IAH → SEA
- Departs
- 14:38
- Flights
- 361
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s AS 439, check with Alaska Airlines.
AS 439 lands a B+, level with the national rate of 77.3%. About one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 361 flights, with a median arrival 4 minutes early.
Key figures
On time
76.7%
Arrivals under 15 minutes late, of 360 completed flights
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
0.28%
National rate is 1.89%
1 hour+ late
6.1%
National rate is 8.3%
These figures cover 361 flights between September 2025 and August 2026. The median arrival is 4 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 AS 439 flies
AS 439 flies IAH to SEA without a single fixed slot. Its most common scheduled departure was 14:38, used on 69 of 361 flights, with 19:28 (50 flights) next.
- Departs 14:3869 flights19.1%
- Departs 19:2850 flights13.9%
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 14:38 departure sits in the 2pm–5pm window. Across every US flight scheduled in that window the on-time rate is 71.9%, and AS 439 runs 5 points better at 76.7%. 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
AS 439 next to IAH to SEA
Every carrier on IAH to SEA combined arrived on time 80.7% of the time across 2,072 flights, so AS 439 is 4 points behind it. Alaska flew 842 flights on the same city pair under all its flight numbers, including this one, and those ran 81.9% on time. Across its whole network Alaska Airlines managed 79.7%, which this flight trails by 3 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| AS 439thin sample | 361 | 76.7% | 57 min | 0.28% | B+ |
| All Alaska Airlines on IAH–SEA | 842 | 81.9% | 52 min | 0.48% | B+ |
| All carriers on IAH–SEA | 2,072 | 80.7% | 52 min | 0.24% | B+ |
| Alaska Airlines, whole network | 309,844 | 79.7% | 52 min | 1.20% | 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 Oct–Dec 2025 at 61.5%, a swing of 29 points on roughly 72 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 flights83.3%
- Oct–Dec 202591 flights61.5%
- Jan–Mar 202688 flights71.3%
- Apr–Jun 202691 flights90.1%
- Jul–Sep 202661 flights83.6%
Scale runs 55% to 95%.
By weekday, AS 439 did best on Tuesday at 82.7% on time and worst on Saturday at 66.7%. Each day rests on about 52 flights, so a gap of 16 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late AS 439 runs when it is late
AS 439 often beats the schedule: 94 of 360 completed flights, 26%, arrived 15 minutes or more early. The 84 late arrivals split 27 under half an hour, 35 between 30 and 60 minutes, and 22 an hour or more.
- 15+ min early94 flights26.1%
- Within 15 min182 flights50.6%
- 15–29 min late27 flights7.5%
- 30–59 min late35 flights9.7%
- 1–2 hours late15 flights4.2%
- 2+ hours late7 flights1.9%
Scale runs 0% to 100%.
Share of 360 completed flights by arrival against schedule.
A late pushback is often recovered here: of 108 departures that left 15 minutes late or more, 40 still arrived on time. 16 flights left on time and still arrived late.
The worst days
Worst days for AS 439
The latest arrival of the period was on 6 July 2026, 6 hours 35 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 6 July 2026 | 6 hours 35 minutes | Carrier |
| 23 October 2025 | 4 hours 10 minutes | Carrier |
| 16 March 2026 | 3 hours 54 minutes | Late-arriving aircraft |
| 24 November 2025 | 3 hours 21 minutes | Late-arriving aircraft |
| 31 October 2025 | 2 hours 15 minutes | Carrier |
Delay causes
Why AS 439 runs late
Late-arriving aircraft accounts for 44% of the 4,798 delay minutes carriers reported here, and the remaining four split what is left.
- 44%Late-arriving aircraft
- 26%National Airspace System
- 26%Carrier
- 2%Extreme weather
- 1%Security
44% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 4,798 reported delay minutes here, that single category outweighs weather by 25 to one. The split is drawn from 4,798 delay minutes reported on AS 439.
Cancellations are rare at 0.28%, 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
6.1% 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 1,874 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, read AS 439 as 76.7% on time with 0.28% cancelled over 361 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- IAH to SEA, every carrier and departure
- SEA to IAH, the return direction
- Alaska Airlines 453 on the same route87.0%
- United Airlines 2456 on the same route74.5%
- George Bush Intercontinental (IAH) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- Alaska Airlines on-time record
- Every Alaska Airlines flight number with a record
- The most and least reliable flight numbers in the US
- Why the first flight of the morning is statistically safest
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 ; recomputed monthly. How this data is collected.