Carrier route record
DLJFK→SEA
Delta Air Lines · New York to Seattle
- Flights
- 1,338
- Period
- July 2025 to June 2026
- Share of route
- 46%
- Carriers
- 3
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on JFK to SEA sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 1,338 flights, with a median arrival 3 minutes early.
The national on-time rate over the same period is 77.6%, so Delta on JFK to SEA runs 4 points behind the country as a whole. Across a thousand flights that is about 44 extra late arrivals.
Key figures
On time
73.2%
Arrivals under 15 minutes late, of 1,299 completed flights
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
2.32%
National rate is 1.81%
Whole route
69.7%
Every carrier on JFK to SEA, 2,906 flights
These figures cover 1,338 flights between July 2025 and June 2026. The median arrival is 3 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 JFK to SEA
Delta flew 1,338 of the 2,906 flights on JFK to SEA, about 46% of it. Its 73.2% on time is 4 points better than the route as a whole, which runs 69.7%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Delta at 73.2% to Alaska at 66.2%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines (this page) | 1,338 | 73.2% | 57 min | 2.32% | C |
| JetBlue Airwaysthin sample | 166 | 71.3% | 98 min | 1.20% | C |
| Alaska Airlines | 1,402 | 66.2% | 61 min | 3.00% | C |
Flight by flight
Delta flight numbers on JFK 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 19 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am327 flights74.8%
- 8am–11am39 flights75.7%
- 11am–2pm249 flights86.1%
- 2pm–5pm250 flights70.0%
- 5pm–8pm473 flights66.7%
- 8pm–5am—
Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.
The best window here is not the first bank but the 11am–2pm slot at 86.1% on time, ahead of 5pm–8pm at 66.7%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 5pm–8pm window is the busiest, with 473 flights scheduled in it.
Across the year
Delta on JFK to SEA through the year
December is the weak month at 39.2% on time, against 87.4% 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. May was the busiest month here, with 124 flights.
Across the week, Wednesday is the strongest day at 76.5% on time and Sunday the weakest at 68.1%. 8 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. National Airspace System accounts for 45% of the 20,000 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.
- 45%National Airspace System
- 33%Carrier
- 18%Late-arriving aircraft
- 4%Extreme weather
45% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 9,065 minutes out of 20,000, against a national NAS share of 21%. The split is drawn from 19,953 reported delay minutes.
Cancellations sit at 2.32% against a national 1.81%, which is ordinary. Diversions add another 0.60%.
Connections and stage length
What a delay here costs
7.1% 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 an hour, which a normal layover absorbs.
At 2,422 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.
The return leg is a different operation and performs like one: it runs 79.6% on time across 1,337 flights, 6 points above 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 6 points of difference.
The sample behind these figures is 1,338 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 JFK to SEA
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 87.4% on time and December 39.2%, a swing of 48 points. If the dates move at all, move them out of December before you think about anything else. 1,299 completed flights over 12 months sit behind that.
Related
Where to go next
- JFK to SEA, every carrier
- Delta on SEA to JFK, the return leg
- JetBlue Airways on JFK to SEA71.3%
- Alaska Airlines on JFK to SEA66.2%
- Delta Air Lines network-wide record
- John F. Kennedy International (JFK) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
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.