Carrier route record
UAEWR→SEA
United Airlines · Newark to Seattle
- Flights
- 997
- Period
- July 2025 to June 2026
- Share of route
- 45%
- Carriers
- 2
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with United Airlines.
United on EWR to SEA lands a B, level with the national rate of 77.6%. Roughly one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 997 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 United on EWR to SEA from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
77.1%
Arrivals under 15 minutes late, of 984 completed flights
Avg delay
61 min
Across delayed arrivals only, not all flights
Cancelled
1.00%
National rate is 1.81%
Whole route
73.5%
Every carrier on EWR to SEA, 2,234 flights
These figures cover 997 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
United against every carrier on EWR to SEA
United flew 997 of the 2,234 flights on EWR to SEA, about 45% of it. Its 77.1% on time is 4 points better than the route as a whole, which runs 73.5%. Ranked by on-time rate it is first 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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines (this page) | 997 | 77.1% | 61 min | 1.00% | B |
| Alaska Airlines | 1,237 | 70.6% | 66 min | 2.83% | C |
Flight by flight
United flight numbers on EWR to SEA
Departure window
When United runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 25 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–8am184 flights87.9%
- 8am–11am248 flights79.6%
- 11am–2pm49 flights85.7%
- 2pm–5pm152 flights78.7%
- 5pm–8pm218 flights63.1%
- 8pm–5am146 flights75.9%
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 63.1% on time, against 87.9% for the 5am–8am 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 8am–11am window is the busiest, with 248 flights scheduled in it.
Across the year
United on EWR to SEA through the year
September is the best month on the calendar at 91.9% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. July was the busiest month here, with 124 flights.
Across the week, Tuesday is the strongest day at 79.4% on time and Sunday the weakest at 73.6%. 6 points is a smaller lever than departure hour, but it is free.
Delay causes
Why United 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 14,000 reported delay minutes.
- 36%National Airspace System
- 34%Late-arriving aircraft
- 28%Carrier
- 1%Extreme weather
34% 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 14,000 reported delay minutes here, that single category outweighs weather by 25 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 13,702 reported delay minutes.
36% 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 4,927 minutes out of 14,000, against a national NAS share of 21%.
Cancellations sit at 1.00% against a national 1.81%, which is ordinary. Diversions add another 0.30%.
Connections and stage length
What a delay here costs
7.9% 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 2,402 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 81.4% on time across 997 flights, 4 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 4 points of difference.
One caution: this is a thin sample. 997 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking United on EWR to SEA
Put together: treat all of this as provisional. 997 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 77.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 984 completed flights over 12 months sit behind that.
Related
Where to go next
- EWR to SEA, every carrier
- United on SEA to EWR, the return leg
- Alaska Airlines on EWR to SEA70.6%
- United Airlines network-wide record
- Newark Liberty International (EWR) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
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.