Carrier route record
DLPHX→SEA
Delta Air Lines · Phoenix to Seattle
- Flights
- 1,767
- Period
- September 2025 to August 2026
- Share of route
- 25%
- Carriers
- 7
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on PHX to SEA earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 10 points better than the national rate of 77.3%. When something does go wrong the average delay runs a little over an hour. That rests on 1,767 flights. The strongest carrier on the route with a full sample, Envoy Air, flew 761 at 87.6% on time.
Envoy Air is the most reliable of the four carriers covered here at 87.6% on time across 761 flights.
Key figures
On time
87.5%
Arrivals under 15 minutes late, of 1,747 completed flights
Avg delay
75 min
Across delayed arrivals only, not all flights
Cancelled
0.96%
National rate is 1.89%
Whole route
82.2%
Every carrier on PHX to SEA, 7,202 flights
These figures cover 1,767 flights between September 2025 and August 2026. The median arrival is 14 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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Carrier by carrier
Delta against every carrier on PHX to SEA
Delta flew 1,767 of the 7,202 flights on PHX to SEA, about 25% of it. Its 87.5% on time is 5 points better than the route as a whole, which runs 82.2%. Ranked by on-time rate it is number two of seven carriers on the route, where the range runs from Envoy at 87.6% to Southwest at 62.2%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. Envoy Air arrives on time 87.6% of the time; Southwest Airlines manages 62.2%. Sample sizes sit next to every figure, because a two-point gap across 1,039 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Air | 761 | 87.6% | 50 min | 0.00% | A+ |
| Delta Air Lines (this page) | 1,767 | 87.5% | 75 min | 0.96% | A+ |
| Alaska Airlines | 2,886 | 84.4% | 56 min | 0.76% | B+ |
| Frontier Airlinesthin sample | 116 | 83.6% | 83 min | 0.00% | B+ |
| SkyWest Airlines | 409 | 83.0% | 63 min | 0.49% | B+ |
| American Airlinesthin sample | 224 | 82.5% | 63 min | 0.45% | B+ |
| Southwest Airlines | 1,039 | 62.2% | 45 min | 0.77% | D+ |
The spread between Envoy and Southwest is 25 points, wide enough that it should decide the booking. On a hundred trips that is 25 more arrivals inside the on-time window.
Flight by flight
Delta flight numbers on PHX to SEA
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Departure window
When Delta runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 13 points, against 25 points between the best and worst carrier.
- 5am–8am317 flights93.6%
- 8am–11am225 flights89.6%
- 11am–2pm403 flights91.5%
- 2pm–5pm484 flights81.1%
- 5pm–8pm256 flights84.7%
- 8pm–5am82 flights85.4%
Scale runs 75% to 100%.
Book the early departure. Flights leaving between 5am–8am arrive on time 93.6% of the time, against 81.1% for the afternoon window. That is 13 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 484 flights scheduled in it.
Across the year
Delta on PHX to SEA through the year
December is the weak month at 80.8% on time, against 92.4% in September. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. August was the busiest month here, with 155 flights.
Across the week, Saturday is the strongest day at 92.1% on time and Monday the weakest at 81.6%, a spread of 11 points.
Arrival by arrival
How late Delta on PHX to SEA runs when it is late
Delta on PHX to SEA often beats the schedule: 823 of 1,747 completed flights, 47%, arrived 15 minutes or more early. The 218 late arrivals split 88 under half an hour, 52 between 30 and 60 minutes, and 78 an hour or more.
- 15+ min early823 flights47.1%
- Within 15 min706 flights40.4%
- 15–29 min late88 flights5.0%
- 30–59 min late52 flights3.0%
- 1–2 hours late40 flights2.3%
- 2+ hours late38 flights2.2%
Scale runs 0% to 100%.
Share of 1,747 completed flights by arrival against schedule.
61 of 242 late departures made up the time and arrived on time, 25% of them. 37 flights left on time and still arrived late.
The worst days
Worst days for Delta on PHX to SEA
The latest arrival of the period was on 26 September 2025, 9 hours 49 minutes behind schedule; most of its delay minutes were filed as extreme weather. The five worst days are spread across September, November, January and March, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 26 September 2025 | 9 hours 49 minutes | Extreme weather |
| 6 November 2025 | 8 hours 53 minutes | National Airspace System |
| 26 September 2025 | 7 hours 47 minutes | Late-arriving aircraft |
| 6 January 2026 | 6 hours 10 minutes | Late-arriving aircraft |
| 11 March 2026 | 5 hours 56 minutes | Carrier |
Delay causes
Why Delta runs late on this route
Late-arriving aircraft accounts for 56% of the 16,000 delay minutes carriers reported here, and the remaining four split what is left.
- 56%Late-arriving aircraft
- 27%Carrier
- 12%National Airspace System
- 5%Extreme weather
56% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 16,000 reported delay minutes here, that single category outweighs weather by 11 to one. The split is drawn from 16,290 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 93.6% on time here.
Cancellations sit at 0.96% against a national 1.89%, which is ordinary. Diversions add another 0.17%.
Connections and stage length
What a delay here costs
Badly late arrivals are rare here: only 4.5% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
The 1,107 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
The return leg is a different operation and performs like one: it runs 80.9% on time across 1,768 flights, 7 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 7 points of difference.
The sample behind these figures is 1,767 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
What to do with this
Booking Delta on PHX to SEA
Put together: take the 5am–8am departure, avoid December if the dates are flexible, and if two carriers are within a few dollars of each other, Envoy is the one with the record behind it. None of that guarantees an on-time arrival; it moves the odds by 25 points, which is the most any booking decision can do. 1,747 completed flights over 12 months sit behind that.
Related
Where to go next
- PHX to SEA, every carrier
- Delta on SEA to PHX, the return leg
- Envoy Air on PHX to SEA87.6%
- Alaska Airlines on PHX to SEA84.4%
- Frontier Airlines on PHX to SEA83.6%
- SkyWest Airlines on PHX to SEA83.0%
- American Airlines on PHX to SEA82.5%
- Southwest Airlines on PHX to SEA62.2%
- Delta Air Lines network-wide record
- Phoenix Sky Harbor International (PHX) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
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.