Route reliability record
SEA→EWR
Seattle to Newark
- Flights
- 2,264
- Period
- September 2025 to August 2026
- Distance
- 2,402 mi
- Carriers
- 2
This route lands a B, 6 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 2,264 SEA to EWR flights, of which United Airlines flew 990 at 84.2% on time.
Best time to fly SEA to EWR: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 93.8% of the time and Wednesday flights 89.4%, against 83.4% for the route overall.
Set against the rest of the country, this route's record is 6 points better than the US average of 77.3%. That gap is worth roughly 61 fewer late arrivals for every thousand flights.
Key figures
On time
83.4%
Arrivals under 15 minutes late, of 2,200 completed flights
Avg delay
67 min
Across delayed arrivals only, not all flights
Cancelled
2.12%
National rate is 1.89%
Best carrier
United
84.2% on time across 990 flights
These figures cover 2,264 flights between September 2025 and August 2026. The median arrival is 15 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.
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Carrier by carrier
Which airline is most reliable on SEA to EWR
The two carriers here are closely matched: 2 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 990 | 84.2% | 87 min | 1.92% | B |
| Alaska Airlines | 1,274 | 82.7% | 54 min | 2.28% | B |
No carrier stands out. United tops the table at 84.2%, 2 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on SEA to EWR
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly Seattle to Newark
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 2 of the top 4 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SEA → EWRSeattle to Newark | United Airlines | 82.6% | 84.2% | 1.92% | 5am–8am, Wed | — |
| 2. SEA → EWRSeattle to Newark | Alaska Airlines | 80.8% | 82.7% | 2.28% | 5am–8am, Wed | AS 477 10:05 |
| 3. SEA → JFKSeattle to New York | Delta Air Lines | 76.8% | 79.3% | 3.21% | 5am–8am, Wed | DL 429 07:15 |
| 4. SEA → JFKSeattle to New York | Alaska Airlines | 75.6% | 77.7% | 2.64% | 5am–8am, Tue | AS 26 07:00 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 22 points, against 2 points between the best and worst carrier.
- 5am–8am518 flights93.8%
- 8am–11am594 flights79.0%
- 11am–2pm247 flights72.1%
- 2pm–5pm246 flights73.6%
- 5pm–8pm—
- 8pm–5am659 flights87.0%
Scale runs 65% to 100%. 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 72.1% on time against 93.8% 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 8pm–5am window is the busiest, with 659 flights scheduled in it.
Explore
Filter SEA to EWR by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On SEA to EWR, the best departure window is 5am–8am at 93.8% on time and the worst is 11am–2pm at 72.1%, a wide gap of 21.7 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am93.8%
- 8–11am79.0%
- 11am–2pm72.1%
- 2–5pm73.6%
- 5–8pm—
- 8pm–5am87.0%
best all US flightsScale 60% to 100%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 14 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
July is the worst month at 75.1% on time, 14 points below April, the best at 89.5%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. July was the busiest month here, with 246 flights.
Across the week, Wednesday is the strongest day at 89.4% on time and Monday the weakest at 79.3%, a spread of 10 points.
Delay causes
Why this route gets delayed
National Airspace System accounts for 45% of the 25,000 delay minutes carriers reported here, and the remaining four split what is left.
- 45%National Airspace System
- 27%Carrier
- 22%Late-arriving aircraft
- 6%Extreme weather
- 0%Security
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 11,000 minutes out of 25,000, against a national NAS share of 21%. The split is drawn from 24,674 reported delay minutes.
Cancellations sit at 2.12% against a national 1.89%, which is ordinary. Diversions add another 0.71%.
Connections and stage length
What a delay here actually costs
6.4% of arrivals land an hour or more late, close to the national 8.3%, so 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 72.9% on time across 2,263 flights, 11 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 11 points of difference.
The sample behind these figures is 2,264 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.
Work out the risk of missing a connection in EWR after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 89.5% on time and July 75.1%, a swing of 14 points. If the dates move at all, move them out of July before you think about anything else. 2,200 completed flights over 12 months sit behind that.
Common questions
SEA to EWR questions
How often is SEA to EWR delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 16.6% of the 2,264 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on SEA to EWR?
United Airlines leads at 84.2% on time across 990 flights. Alaska Airlines is at the other end on 82.7%, a gap of 2 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on SEA to EWR?
The 5am–8am departure window is the strongest at 93.8% on time. The 11am–2pm window is the weakest at 72.1%, 22 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are July delays on SEA to EWR?
July is the weakest month at 75.1% on time, compared with 89.5% in April. Across the year that is 14 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- EWR to SEA — the return legseparate record
- Seattle-Tacoma International (SEA) delay statistics
- Newark Liberty International (EWR) delay statistics
- United Airlines on SEA to EWR84.2%
- Alaska Airlines on SEA to EWR82.7%
- SEA to LAX, a related route82.0%
- MCO to EWR, a related route75.0%
- SEA to PHX, a related route78.2%
- United Airlines on-time record84.2%
- Alaska Airlines on-time record82.7%
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. SEA to EWR and EWR to SEA are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.