Carrier route record

ASEWR→SEA

Alaska Airlines · Newark to Seattle

Flights: 1,237
Period: July 2025 to June 2026
Share of route: 55%
Carriers: 2

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Alaska Airlines.

Alaska on EWR to SEA sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 7 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 1,237 flights, with a median arrival 3 minutes early.

The national on-time rate over the same period is 77.6%, so Alaska on EWR to SEA runs 7 points behind the country as a whole. Across a thousand flights that is about 70 extra late arrivals.

On time

70.6%

Arrivals under 15 minutes late, of 1,201 completed flights

Avg delay

66 min

Across delayed arrivals only, not all flights

Cancelled

2.83%

National rate is 1.81%

Whole route

73.5%

Every carrier on EWR to SEA, 2,234 flights

These figures cover 1,237 flights between July 2025 and June 2026. Beyond the headline rate, 9.1% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Carrier by carrier

Alaska against every carrier on EWR to SEA

Alaska flew 1,237 of the 2,234 flights on EWR to SEA, most of the route. Its 70.6% on time is 3 points worse than the route as a whole, which runs 73.5%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from United at 77.1% to Alaska at 70.6%.

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 EWR to SEA
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	997	77.1%	61 min	1.00%	B
Alaska Airlines (this page)	1,237	70.6%	66 min	2.83%	C

Flight by flight

Alaska flight numbers on EWR to SEA

Departure window

When Alaska runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 58 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–8am301 flights73.4%
8am–11am98 flights90.7%
11am–2pm—
2pm–5pm292 flights78.6%
5pm–8pm500 flights63.8%
8pm–5am46 flights32.6%

Scale runs 25% to 95%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 32.6% on time, against 90.7% for the 8am–11am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 5pm–8pm window is the busiest, with 500 flights scheduled in it.

Across the year

Alaska on EWR to SEA through the year

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

December is the weak month at 38.9% on time, against 92.4% in April. 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, Thursday is the strongest day at 73.7% on time and Sunday the weakest at 66.5%. 7 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Alaska runs late on this route

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 23,000 reported delay minutes.

National Airspace System
39%
Late-arriving aircraft
37%
Carrier
11%
Extreme weather
11%
Security
2%

37% 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 23,000 reported delay minutes here, that single category outweighs weather by 3 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 23,179 reported delay minutes.

39% 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 8,973 minutes out of 23,000, against a national NAS share of 21%.

Cancellations run at 2.83%, against 1.81% nationally. That is roughly one flight in 40 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.

Connections and stage length

What a delay here costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.1% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

At 2,402 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 81.0% on time across 1,238 flights, 10 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 10 points of difference.

The sample behind these figures is 1,237 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 Alaska on EWR to SEA

Put together: the delay figures matter less here than the 2.83% cancellation rate. A late arrival costs you about an hour; a cancelled flight costs you the day. Book the 8am–11am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 1,201 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