Carrier route record

DLSEA→JFK

Delta Air Lines · Seattle to New York

Flights: 1,337
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 SEA to JFK lands a B, 2 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 1,337 flights, with a median arrival 7 minutes early.

The US average over the same twelve months is 77.6%, so there is little to separate Delta on SEA to JFK from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

79.6%

Arrivals under 15 minutes late, of 1,289 completed flights

Avg delay

70 min

Across delayed arrivals only, not all flights

Cancelled

2.39%

National rate is 1.81%

Whole route

75.3%

Every carrier on SEA to JFK, 2,906 flights

These figures cover 1,337 flights between July 2025 and June 2026. The median arrival is 7 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 SEA to JFK

Delta flew 1,337 of the 2,906 flights on SEA to JFK, about 46% of it. Its 79.6% on time is 4 points better than the route as a whole, which runs 75.3%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Delta at 79.6% to Alaska at 71.6%. 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.

On-time performance by carrier on SEA to JFK
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines (this page)	1,337	79.6%	70 min	2.39%	B
JetBlue Airwaysthin sample	166	72.0%	78 min	1.20%	C
Alaska Airlines	1,403	71.6%	54 min	2.57%	C

Flight by flight

Delta flight numbers on SEA to JFK

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 18 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–8am365 flights87.9%
8am–11am—
11am–2pm339 flights70.2%
2pm–5pm272 flights79.2%
5pm–8pm—
8pm–5am361 flights80.6%

Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.

The weak window here is the middle of the day, not the evening: 11am–2pm runs 70.2% on time against 87.9% for 5am–8am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 5am–8am window is the busiest, with 365 flights scheduled in it.

Across the year

Delta on SEA to JFK through the year

Darker means more delays. Figures are on-time percentages.February best, December worst

December is the weak month at 70.7% on time, against 88.3% in February. 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, Tuesday is the strongest day at 83.3% on time and Sunday the weakest at 73.9%. 9 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. Carrier accounts for 48% of the 19,000 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.

Carrier
48%
National Airspace System
28%
Late-arriving aircraft
20%
Extreme weather
3%
Security
0%

The largest share of delay minutes, 48%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 8,936 of the 19,000 delay minutes reported here. The split is drawn from 18,502 reported delay minutes.

Cancellations sit at 2.39% against a national 1.81%, which is ordinary. Diversions add another 1.20%.

Connections and stage length

What a delay here costs

6.4% 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 a little over 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 73.2% on time across 1,338 flights, 6 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 6 points of difference.

The sample behind these figures is 1,337 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 SEA to JFK

Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 88.3% on time and December 70.7%, a swing of 18 points. If the dates move at all, move them out of December before you think about anything else. 1,289 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures