Route reliability record
FLL→SEA
Fort Lauderdale to Seattle
- Flights
- 826
- Period
- September 2025 to August 2026
- Distance
- 2,717 mi
- Carriers
- 2
This route 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 77.3%. The late ones land roughly 55 minutes behind schedule. That rests on 826 FLL to SEA flights, with a median arrival 2 minutes early.
Best time to fly FLL to SEA: a 8am–11am departure, ideally on a Thursday. Flights in that window arrived on time 79.2% of the time and Thursday flights 81.0%, against 73.3% for the route overall.
The national on-time rate over the same period is 77.3%, so this route runs 4 points behind the country as a whole. Across a thousand flights that is about 40 extra late arrivals.
Key figures
On time
73.3%
Arrivals under 15 minutes late, of 805 completed flights
Avg delay
53 min
Across delayed arrivals only, not all flights
Cancelled
1.21%
National rate is 1.89%
Best carrier
Alaska
68.4% on time across 462 flights
These figures cover 826 flights between September 2025 and August 2026. The median arrival is 2 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 FLL to SEA
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 Linesthin sample | 364 | 79.5% | 58 min | 1.37% | B |
| Alaska Airlines | 462 | 68.4% | 50 min | 1.08% | C |
Flight by flight
Flights on FLL to SEA
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 Fort Lauderdale to Seattle
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. 3 of the top 4 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. MIA → SEAMiami to Seattle | American Airlines | 72.2% | 72.5% | 0.42% | 8am–11am, Wed | — |
| 2. MIA → SEAMiami to Seattle | Alaska Airlines | 68.2% | 69.1% | 1.28% | 5am–8am, Tue | AS 305 18:20 |
| 3. FLL → SEAFort Lauderdale to Seattle | Alaska Airlines | 67.7% | 68.4% | 1.08% | 5pm–8pm, Thu | AS 517 18:30 |
| 4. MIA → SEAMiami to Seattle | Delta Air Lines | 62.4% | 63.4% | 1.64% | 5pm–8pm, Tue | DL 506 18:05 |
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 11 points, against half a point between the best and worst carrier.
- 5am–8am109 flights68.3%
- 8am–11am329 flights79.2%
- 11am–2pm—
- 2pm–5pm—
- 5pm–8pm388 flights69.7%
- 8pm–5am—
Scale runs 60% to 85%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 79.2% of the time, against 68.3% for the early window. That is 11 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 388 flights scheduled in it.
Explore
Filter FLL to SEA 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 FLL to SEA, the best departure window is 8am–11am at 79.2% on time and the worst is 5am–8am at 68.3%, a wide gap of 10.9 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am68.3%
- 8–11am79.2%
- 11am–2pm—
- 2–5pm—
- 5–8pm69.7%
- 8pm–5am—
best all US flightsScale 60% to 95%. Cells under 30 flights show a dash.
Across the year
When delays peak on this route
This route's year swings by 43 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.
December is the weak month at 48.9% on time, against 91.7% in June. 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. December was the busiest month here, with 93 flights.
Across the week, Thursday is the strongest day at 81.0% on time and Sunday the weakest at 61.9%, a spread of 19 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 45% of the 11,000 delay minutes carriers reported here, and the remaining four split what is left.
- 45%Late-arriving aircraft
- 30%National Airspace System
- 19%Carrier
- 6%Extreme weather
- 0%Security
45% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 11,000 reported delay minutes here, that single category outweighs weather by 8 to one. The split is drawn from 11,397 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 79.2% on time here.
Cancellations sit at 1.21% against a national 1.89%, which is ordinary. Diversions add another 1.33%.
Connections and stage length
What a delay here actually costs
5.5% 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 roughly 55 minutes, which a normal layover absorbs.
At 2,717 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 78.6% on time across 826 flights, 5 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 5 points of difference.
One caution: this is a thin sample. 826 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.
Work out the risk of missing a connection in SEA after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 826 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 73.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 805 completed flights over 12 months sit behind that.
Common questions
FLL to SEA questions
How often is FLL to SEA delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 26.7% of the 826 flights in this analysis, against 22.7% nationally. Delayed flights are late by roughly 55 minutes on average.
How reliable is FLL to SEA compared with the rest of the country?
73.3% of flights arrive on time here against a national 77.3%, a difference of 4 points against it. That is worth a C on this site's grading scale.
What time of day has the fewest delays on FLL to SEA?
The 8am–11am departure window is the strongest at 79.2% on time. The 5am–8am window is the weakest at 68.3%, 11 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 December delays on FLL to SEA?
December is the weakest month at 48.9% on time, compared with 91.7% in June. Across the year that is 43 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
- SEA to FLL — the return legseparate record
- Fort Lauderdale-Hollywood International (FLL) delay statistics
- Seattle-Tacoma International (SEA) delay statistics
- Delta Air Lines on FLL to SEA79.5%
- Alaska Airlines on FLL to SEA68.4%
- FLL to ATL, a related route71.0%
- LAX to SEA, a related route85.0%
- FLL to LGA, a related route64.8%
- Delta Air Lines on-time record79.5%
- Alaska Airlines on-time record68.4%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. FLL to SEA and SEA to FLL 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.