Carrier route record
DLPHX→SEA
Delta Air Lines · Phoenix to Seattle
- Flights
- 1,764
- Period
- July 2025 to June 2026
- Share of route
- 24%
- Carriers
- 7
Historical statistics for July 2025 to June 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 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 1,764 flights. The strongest carrier on the route with a full sample, Envoy Air, flew 692 at 87.1% on time.
Set against the rest of the country, Delta's PHX to SEA record is 10 points better than the US average of 77.6%. That gap is worth roughly 102 fewer late arrivals for every thousand flights.
Key figures
On time
87.8%
Arrivals under 15 minutes late, of 1,746 completed flights
Avg delay
73 min
Across delayed arrivals only, not all flights
Cancelled
0.85%
National rate is 1.81%
Whole route
82.7%
Every carrier on PHX to SEA, 7,269 flights
These figures cover 1,764 flights between July 2025 and June 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.
Carrier by carrier
Delta against every carrier on PHX to SEA
Delta flew 1,764 of the 7,269 flights on PHX to SEA, about 24% of it. Its 87.8% on time is 5 points better than the route as a whole, which runs 82.7%. Ranked by on-time rate it is first of seven carriers on the route, where the range runs from Delta at 87.8% to Southwest at 64.8%. 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 87.1% of the time; Southwest Airlines manages 64.8%. Sample sizes sit next to every figure, because a two-point gap across 1,037 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines (this page) | 1,764 | 87.8% | 73 min | 0.85% | A+ |
| Envoy Air | 692 | 87.1% | 45 min | 0.00% | A+ |
| Frontier Airlinesthin sample | 165 | 86.1% | 80 min | 0.00% | A+ |
| Alaska Airlines | 2,903 | 84.9% | 56 min | 0.76% | B+ |
| SkyWest Airlines | 506 | 82.6% | 61 min | 0.59% | B+ |
| American Airlinesthin sample | 202 | 81.6% | 53 min | 0.50% | B+ |
| Southwest Airlines | 1,037 | 64.8% | 43 min | 0.58% | D+ |
The spread between Envoy and Southwest is 22 points, wide enough that it should decide the booking. On a hundred trips that is 22 more arrivals inside the on-time window.
Flight by flight
Delta flight numbers on PHX to SEA
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 14 points, against 22 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am317 flights95.5%
- 8am–11am163 flights88.8%
- 11am–2pm465 flights91.8%
- 2pm–5pm484 flights81.7%
- 5pm–8pm253 flights82.5%
- 8pm–5am82 flights85.4%
Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 95.5% of the time, against 81.7% for the afternoon window. That is 14 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. October was the busiest month here, with 154 flights.
Across the week, Tuesday is the strongest day at 90.9% on time and Monday the weakest at 83.6%. 7 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Delta runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 56% of the 16,000 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.
- 56%Late-arriving aircraft
- 25%Carrier
- 13%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. That is a cascade, and cascades start small and grow through the day. Across 16,000 reported delay minutes here, that single category outweighs weather by 11 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 15,544 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 95.5% on time here.
Cancellations are rare at 0.85%, 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 stage length
What a delay here costs
Badly late arrivals are rare here: only 4.2% land an hour or more behind schedule, against 8.1% 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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The return leg is a different operation and performs like one: it runs 82.6% on time across 1,765 flights, 5 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 5 points of difference.
The sample behind these figures is 1,764 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 22 points, which is the most any booking decision can do. 1,746 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 SEA87.1%
- Frontier Airlines on PHX to SEA86.1%
- Alaska Airlines on PHX to SEA84.9%
- SkyWest Airlines on PHX to SEA82.6%
- American Airlines on PHX to SEA81.6%
- Southwest Airlines on PHX to SEA64.8%
- 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.