Route reliability record
SEA→FLL
Seattle to Fort Lauderdale
- Flights
- 826
- Period
- September 2025 to August 2026
- Distance
- 2,717 mi
- Carriers
- 2
This route lands a B+, about a point better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about 45 minutes on average. That rests on 826 SEA to FLL flights, with a median arrival 6 minutes early.
Best time to fly SEA to FLL: a 8am–11am departure, ideally on a Wednesday. Flights in that window arrived on time 83.6% of the time and Wednesday flights 91.2%, against 78.6% for the route overall.
The US average over the same twelve months is 77.3%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
78.6%
Arrivals under 15 minutes late, of 816 completed flights
Avg delay
45 min
Across delayed arrivals only, not all flights
Cancelled
0.73%
National rate is 1.89%
Best carrier
Alaska
81.1% on time across 462 flights
These figures cover 826 flights between September 2025 and August 2026. The median arrival is 6 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 FLL
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 |
|---|---|---|---|---|---|
| Alaska Airlines | 462 | 81.1% | 44 min | 0.22% | B+ |
| Delta Air Linesthin sample | 364 | 75.3% | 47 min | 1.37% | B |
Flight by flight
Flights on SEA to FLL
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 Fort Lauderdale
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. SEA → FLLSeattle to Fort Lauderdale | Alaska Airlines | 80.9% | 81.1% | 0.22% | 8am–11am, Wed | AS 516 08:23 |
| 2. SEA → MIASeattle to Miami | Alaska Airlines | 80.3% | 80.5% | 0.26% | 8am–11am, Tue | AS 305 08:12 |
| 3. SEA → MIASeattle to Miami | Delta Air Lines | 79.6% | 80.7% | 1.37% | 5am–8am, Wed | DL 506 08:00 |
| 4. SEA → MIASeattle to Miami | American Airlines | 77.7% | 78.4% | 0.84% | 11am–2pm, Thu | — |
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–8am25 flights—
- 8am–11am375 flights83.6%
- 11am–2pm329 flights73.2%
- 2pm–5pm—
- 5pm–8pm—
- 8pm–5am97 flights72.2%
Scale runs 65% to 90%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 83.6% of the time, against 72.2% for the overnight 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 8am–11am window is the busiest, with 375 flights scheduled in it.
Explore
Filter SEA to FLL 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 FLL, the best departure window is 8am–11am at 83.6% on time and the worst is 8pm–5am at 72.2%, a wide gap of 11.4 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am—
- 8–11am83.6%
- 11am–2pm73.2%
- 2–5pm—
- 5–8pm—
- 8pm–5am72.2%
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 27 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 64.1% on time, against 91.5% in September. 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, Wednesday is the strongest day at 91.2% on time and Friday the weakest at 70.0%, a spread of 21 points.
Delay causes
Why this route gets delayed
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 7,944 reported delay minutes.
- 41%Carrier
- 37%National Airspace System
- 21%Late-arriving aircraft
- 0%Extreme weather
The largest share of delay minutes, 41%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 3,273 of the 7,944 delay minutes reported here. The split is drawn from 7,944 reported delay minutes.
37% 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 2,953 minutes out of 7,944, against a national NAS share of 21%.
Cancellations are rare at 0.73%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 4.4% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
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 73.3% on time across 826 flights, 5 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 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 FLL 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 78.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 816 completed flights over 12 months sit behind that.
Common questions
SEA to FLL questions
How often is SEA to FLL delayed?
About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.4% of the 826 flights in this analysis, against 22.7% nationally. Delayed flights are late by about 45 minutes on average.
How reliable is SEA to FLL compared with the rest of the country?
78.6% of flights arrive on time here against a national 77.3%, a difference of about a point in its favour. That is worth a B+ on this site's grading scale.
What time of day has the fewest delays on SEA to FLL?
The 8am–11am departure window is the strongest at 83.6% on time. The 8pm–5am window is the weakest at 72.2%, 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 SEA to FLL?
December is the weakest month at 64.1% on time, compared with 91.5% in September. Across the year that is 27 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
- FLL to SEA — the return legseparate record
- Seattle-Tacoma International (SEA) delay statistics
- Fort Lauderdale-Hollywood International (FLL) delay statistics
- Alaska Airlines on SEA to FLL81.1%
- Delta Air Lines on SEA to FLL75.3%
- SEA to LAX, a related route82.0%
- ATL to FLL, a related route70.7%
- SEA to PHX, a related route78.2%
- Alaska Airlines on-time record81.1%
- Delta Air Lines on-time record75.3%
- 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 FLL and FLL 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.