DEN → SEA Flight Reliability

Right now

Origin · DENNo disruption reported

Aviation weather is not currently a factor.

Updated 07:53 UTC

Denver airport profile →

Destination · SEANo disruption reported

Aviation weather is not currently a factor.

Updated 07:53 UTC

Seattle airport profile →

Route reliability

July 2023 – July 2026

Route Reliability Score

65/ 100Good

Better than 47% of comparable major US routes (4,598 compared)

Calculated from 20,290 flights. How this is calculated

On-time arrivals

74.7%

15,045 of 20,138

Cancellation rate

0.67%

135 cancelled

Median arrival delay

-3 min

Average 8.2 min

Severe delays

7.4%

60+ minutes late

Delay when late

58 min

Average, when 15+ min late

Flights analyzed

20,290

6 carriers

DEN → SEA arrives on time 74.7% of the time; the return trip, SEA → DEN, arrives on time 77.9% of the time, a 3.2-point gap between the two directions of the same city pair.

DEN → SEA spends 30.0 minutes on the ground on a 1,024-mile trip: 18.4 minutes from pushback to wheels-up at DEN and 11.6 minutes from touchdown to gate at SEA.

Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026

What stands out

This route has stayed remarkably steady year over year, a smaller swing than 100% of 5,368 comparable routes.

74.6% on time over the most recent 12 months (2025-08 to 2026-07), against 74.6% in the 12 months before (2024-08 to 2025-07), virtually unchanged.

Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Ranked against every other route with the same kind of figure and at least 5,368 in the comparison.

Why DEN → SEA flights are cancelled

July 2023 – July 2026

DEN → SEA cancelled 135 of 20,290 scheduled flights — about 1 in every 150. The reason filed most often was the airline, 64.4% of the cancellations coded on this route — about 1 in every 233 scheduled flights.

Share of cancellations

Airline64.4%

Weather29.6%

Air traffic5.9%

Security0.0%

Of 135 cancelled departures carrying a reason code.

What each reason means

The airline1 in 233

Crew, maintenance, aircraft cleaning, baggage or fueling: what BTS counts as within the carrier’s own control.

87 cancellations, 64.4% of the total.

Extreme weather1 in 507

Conditions the carrier judged severe enough to stop the flight: a blizzard, a hurricane, a line of thunderstorms.

40 cancellations, 29.6% of the total.

The air traffic system1 in 2,536

Airport capacity, air traffic control flow programs, heavy traffic and ordinary bad weather. A system decision, not the airline’s.

8 cancellations, 5.9% of the total.

Security—

A terminal evacuation, a security breach, screening equipment failure, or screening queues over 29 minutes.

0 cancellations, 0.0% of the total.

Reason codes are the operating airline’s own filing with US DOT, not an independent finding of fault. Ordinary bad weather is filed under air traffic, so weather’s full share is larger than its bar.

135 coded cancellations were recorded on DEN → SEA; the section appears from 50.

When it goes wrong

July 2023 – July 2026

One arrival in ten is worse than

47 min late

against a median of 3 min early

Arrived an hour or more late7.4%

Typical delay when late58 min

Cancelled0.67%

Landed somewhere else0.08%

Percentiles over 20,290 operations; cancelled and diverted flights are counted separately.

Will your connection be tight enough?

Layovers at SEA after arriving from DEN.

Connection buffer and chance of missing by layover length, DEN → SEA arrivals
Connection time	Chance of missing	Reads as
30 min	43%	Likely to miss
45 min	25%	High risk
60 min	15%	High risk
90 min	7.3%	Some risk
120 min	4.0%	Low risk

This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 0.67% of the time and diverts 0.08% of the time, which a late arrival never shows up in.

Chance of missing is the share of 20,138 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.

The worst tenth of arrivals on this route land at least 47 minutes late (90th-percentile gate arrival delay), over 20,290 operations.

Any other layover length: connection checker.

Best time to fly

DEN → SEA flights departing 5–9 AM arrived on time 87.4% of the time, against 62.9% for 9 PM–5 AM departures, a gap of 24.5 percentage points.

By day and hour

On-time arrival rate for each weekday and scheduled departure hour, in local time at the departure airport (DEN).

Hour of departure matters more than day of the week: hourly averages sit a typical 10.1 points from the route-wide rate, weekday averages 1.0 points.

On-time arrival rate for DEN to SEA by weekday and scheduled departure hour, local time. Each button reads out one slot.
Hour	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday	Sunday
6 AM–7 AM
7 AM–8 AM
8 AM–9 AM
9 AM–10 AM
10 AM–11 AM
11 AM–12 PM
12 PM–1 PM
1 PM–2 PM
2 PM–3 PM
3 PM–4 PM
4 PM–5 PM
5 PM–6 PM
6 PM–7 PM
7 PM–8 PM
8 PM–9 PM
9 PM–10 PM
10 PM–11 PM

On-time rate, % · stronger color, fewer on time

50–59
60–69
70–79
80–89
90–99

Fewer than 120 flights, not scored

Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · On time is arrival within 15 minutes of schedule. Cells round to whole percentages; the table shows one decimal.

No slot is named best or worst: too few reach 500 flights. Departures before 6 AM and after 11 PM (155 flights) are not drawn: no slot in those hours has enough flights to score.

View as tableHide table

On-time arrival rate (%) with flights beneath, by scheduled departure hour and weekday for DEN to SEA. A dash means fewer than 120 flights, which are not scored.
Hour	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday	Sunday
6 AM–7 AM	90.5% on time360 flights	90.6% on time322 flights	92.2% on time298 flights	90.6% on time365 flights	92.1% on time367 flights	86.5% on time348 flights	86.6% on time358 flights
7 AM–8 AM	87.0% on time192 flights	93.4% on time166 flights	85.9% on time157 flights	88.5% on time191 flights	85.9% on time191 flights	87.8% on time180 flights	89.7% on time156 flights
8 AM–9 AM	81.6% on time213 flights	85.4% on time215 flights	85.3% on time225 flights	76.2% on time229 flights	78.0% on time217 flights	84.2% on time178 flights	89.4% on time230 flights
9 AM–10 AM	54 flights, too few to score	54 flights, too few to score	48 flights, too few to score	50 flights, too few to score	48 flights, too few to score	43 flights, too few to score	62 flights, too few to score
10 AM–11 AM	107 flights, too few to score	99 flights, too few to score	109 flights, too few to score	108 flights, too few to score	106 flights, too few to score	114 flights, too few to score	77 flights, too few to score
11 AM–12 PM	81.2% on time240 flights	81.8% on time226 flights	79.9% on time225 flights	80.0% on time233 flights	77.6% on time237 flights	74.7% on time220 flights	77.6% on time239 flights
12 PM–1 PM	78.8% on time209 flights	79.7% on time193 flights	77.1% on time193 flights	73.8% on time207 flights	78.8% on time230 flights	78.0% on time175 flights	80.3% on time209 flights
1 PM–2 PM	74.2% on time159 flights	83.0% on time165 flights	83.2% on time161 flights	77.9% on time163 flights	79.9% on time151 flights	80.8% on time125 flights	78.6% on time142 flights
2 PM–3 PM	49 flights, too few to score	52 flights, too few to score	57 flights, too few to score	41 flights, too few to score	46 flights, too few to score	84 flights, too few to score	41 flights, too few to score
3 PM–4 PM	72.1% on time200 flights	70.7% on time223 flights	76.7% on time210 flights	70.4% on time201 flights	67.2% on time191 flights	70.4% on time187 flights	66.8% on time201 flights
4 PM–5 PM	71.0% on time183 flights	73.3% on time146 flights	76.8% on time155 flights	71.4% on time186 flights	71.5% on time180 flights	79.4% on time157 flights	67.5% on time167 flights
5 PM–6 PM	97 flights, too few to score	101 flights, too few to score	98 flights, too few to score	91 flights, too few to score	91 flights, too few to score	97 flights, too few to score	94 flights, too few to score
6 PM–7 PM	59.3% on time165 flights	58.9% on time169 flights	61.5% on time179 flights	64.9% on time171 flights	55.5% on time165 flights	68.3% on time167 flights	64.4% on time190 flights
7 PM–8 PM	64.1% on time365 flights	69.5% on time308 flights	70.7% on time311 flights	62.3% on time366 flights	62.6% on time377 flights	69.0% on time333 flights	63.6% on time350 flights
8 PM–9 PM	58.2% on time135 flights	62.2% on time121 flights	66.7% on time157 flights	63.4% on time133 flights	62.8% on time131 flights	109 flights, too few to score	61.4% on time134 flights
9 PM–10 PM	72.0% on time182 flights	67.4% on time136 flights	57.1% on time178 flights	59.8% on time175 flights	68.9% on time178 flights	88 flights, too few to score	66.3% on time164 flights
10 PM–11 PM	87 flights, too few to score	35 flights, too few to score	37 flights, too few to score	93 flights, too few to score	100 flights, too few to score	45 flights, too few to score	62.7% on time136 flights

By departure window

5–9 AM87.4%

9 AM–12 PM79.7%

12–3 PM77.2%

3–6 PM68.6%

6–9 PM64.0%

9 PM–5 AM62.9%

By departure hour

12 AM

3 AM

6 AM

9 AM

12 PM

3 PM

6 PM

9 PM

Why DEN → SEA runs late

July 2023 – July 2026

Late-arriving aircraft48.2%

the inbound aircraft was late, so this flight started late

The airline32.3%

crew, maintenance, boarding and fueling, all within the carrier’s control

Air traffic control16.2%

airspace and airport capacity, including weather-driven flow control

Weather3.2%

weather severe enough to stop this flight specifically

Security0.1%

screening or terminal security incidents

Share of the delay minutes US DOT attributed to each cause for DEN → SEA. Only delays of 15 minutes or more are attributed.

Late-arriving aircraft is the largest cause on DEN → SEA, at 48.2%: flights here mostly leave late because the plane came in late, and the day shows it: 5–9 AM departures arrived on time 87.4% of the time and 9 PM–5 AM departures 62.9%.

How this route holds up in bad weather

July 2023 – July 2026

The harder-hit end is the one the flight leaves from, where a cancellation keeps it from departing at all. Bad weather cancels 4.0 times the normal rate at DEN against 1.9 times at SEA. Cancelled in bad weather against normal hours: DEN 2.8% against 0.7%, SEA 1.5% against 0.8%. Flights that did leave DEN in bad weather arrived on time 51.5% of the time, against 78.8% in normal hours.

Bad weather and normal hours at the airports

Scheduled departures, July 2023 – July 2026

Departures from DEN and SEA in hours of bad weather and in normal hours
Departures from	DEN	SEA
Cancelled in bad weather	2.8%	1.5%
Cancelled in normal hours	0.7%	0.8%
Arrived on time, bad weather	51.5%	75.4%
Arrived on time, normal hours	78.8%	79.3%
Departures in bad weather	92,610	43,416

Of the carriers on this route, United Airlines (1.5% cancelled against 3.5% for the other carriers at DEN) cancelled the fewest departures from DEN in bad weather and SkyWest Airlines (5.8% cancelled against 1.8% for the other carriers at DEN) the most.

This route’s airlines in bad weather at DEN

All departures from DEN

Cancellation rates in bad weather at DEN for the airlines that fly DEN to SEA, against the other carriers at DEN in the same months
Airline	Bad-weather departures	Cancelled	Other carriers
United Airlines	30,853	1.5%below the others	3.5%
Delta Air Lines	3,460	1.1%below the others	2.9%
Alaska Airlines	641	1.4%below the others	2.7%
Southwest Airlines	28,467	2.4%below the others	3.1%
Frontier Airlines	6,740	3.1%about level	2.8%
SkyWest Airlines	19,275	5.8%above the others	1.8%

These are airport figures, not route figures: every scheduled departure from DEN and SEA, to any destination, in hours the weather report called bad. The airline rows count each carrier’s departures from DEN on every route.

Weather source and limits. In full: DEN (airlines), SEA, What Weather Costs Each Airport, Who Cancels More When the Weather Turns, Airports That Change Places When Weather Turns.

Airlines on this route

Carriers with at least 200 flights, by the airline that operated each one.

Airlines on this route
Carrier	Flights	On time	Cancelled	Median delay	Severe
United Airlines	6,063	79.7%	0.64%	-6 min	6.7%
Alaska Airlines	4,902	75.0%	0.94%	-4 min	6.9%
Southwest Airlines	4,527	63.7%	0.27%	6 min	8.5%
Delta Air Lines	2,873	80.3%	0.70%	-9 min	7.4%
Frontier Airlines	1,436	74.6%	1.11%	-5 min	9.0%
SkyWest Airlines	489	80.1%	0.41%	-5 min	7.2%

United Airlines flew 29.9% of the 20,290 flights listed.

Delta Air Lines arrived on time 16.6 percentage points more often than Southwest Airlines on this route.

Flights on this route

Flight numbers with at least 600 operations here and still on the schedule.

Flights on this route
Flight	Scheduled	Operations	On time
DL1731 Delta Air Lines	6:15 AM	1,064	90.1%
AS643 Alaska Airlines	6:00 AM	990	88.2%
UA2651 United Airlines	8:55 PM	806	69.8%

DL1731 (6:15 AM) arrived on time 90.1% of the time, 20.3 points more often than UA2651 (8:55 PM) at 69.8%.

Weekly and seasonal patterns

By day of week

Mon74.9%

Tue76.4%

Wed75.6%

Thu73.6%

Fri73.6%

Sat75.2%

Sun73.8%

Tuesday is historically the most reliable day and Friday the least, a gap of 2.8 percentage points.

By month

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

June is historically the weakest month and November the strongest, a spread of 17.9 percentage points.

Reliability over time

July 2023 – July 2026

24

25

26

Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 74.6% against 74.6% in the 12 months before — broadly unchanged.

Data and methodology

Calculated by FlyerIntel from 20,290 DEN → SEA flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.

Full methodology · Data sources · Report a problem

Analysis last recomputed September 26, 2026

DEN airport SEA airport Return direction SEA → DEN

DEN→SEA

Right now

Route reliability

What stands out

Why DEN → SEA flights are cancelled

Share of cancellations

What each reason means

When it goes wrong

Will your connection be tight enough?

Best time to fly

By day and hour

By departure window

By departure hour

Why DEN → SEA runs late

How this route holds up in bad weather

Bad weather and normal hours at the airports

This route’s airlines in bad weather at DEN

Airlines on this route

Flights on this route

Weekly and seasonal patterns

By day of week

By month

Reliability over time

Data and methodology