Flight number record
DL 459
Delta Air Lines · Seattle to Boston
- Route
- SEA → BOS
- Departs
- 07:50
- Flights
- 365
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 459, check with Delta Air Lines.
DL 459 earns an A. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 11 points better than the national rate of 77.3%. When something does go wrong the average delay runs an hour and a half. That rests on 365 flights, with a median arrival 13 minutes early.
Set against the rest of the country, DL 459's record is 11 points better than the US average of 77.3%. That gap is worth roughly 108 fewer late arrivals for every thousand flights.
Key figures
On time
88.1%
Arrivals under 15 minutes late, of 354 completed flights
Avg delay
84 min
Across delayed arrivals only, not all flights
Cancelled
2.47%
National rate is 1.89%
1 hour+ late
4.8%
National rate is 8.3%
These figures cover 365 flights between September 2025 and August 2026. The median arrival is 13 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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Schedule
When DL 459 flies
DL 459 flies SEA to BOS without a single fixed slot. Its most common scheduled departure was 07:50, used on 59 of 365 flights, with 07:29 (57 flights) and 07:15 (55 flights) next.
- Departs 07:5059 flights16.2%
- Departs 07:2957 flights15.6%
- Departs 07:1555 flights15.1%
Scale runs 0% to 100%.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 07:50 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and DL 459 runs level with that at 88.1%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
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Against the route
DL 459 next to SEA to BOS
Every carrier on SEA to BOS combined arrived on time 75.1% of the time across 2,554 flights, so DL 459 is 13 points ahead of it. Delta flew 1,067 flights on the same city pair under all its flight numbers, including this one, and those ran 79.8% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight beats by 7 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 459 | 365 | 88.1% | 84 min | 2.47% | A |
| All Delta Air Lines on SEA–BOS | 1,067 | 79.8% | 71 min | 1.69% | B |
| All carriers on SEA–BOS | 2,554 | 75.1% | 64 min | 1.49% | B |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 459 quarter by quarter
DL 459 did not run the same all year. Its best quarter was Apr–Jun 2026 at 94.4% on time and its weakest Jul–Sep 2025 at 80.0%, a swing of 14 points on roughly 73 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202530 flights80.0%
- Oct–Dec 202592 flights81.1%
- Jan–Mar 202690 flights89.5%
- Apr–Jun 202691 flights94.4%
- Jul–Sep 202662 flights91.5%
Scale runs 70% to 100%.
By weekday, DL 459 ranged from 82.4% on Wednesday to 92.0% on Sunday. With about 52 flights behind each day, a spread of 10 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late DL 459 runs when it is late
DL 459 often beats the schedule: 160 of 354 completed flights, 45%, arrived 15 minutes or more early. The 42 late arrivals split 14 under half an hour, 11 between 30 and 60 minutes, and 17 an hour or more.
- 15+ min early160 flights45.2%
- Within 15 min152 flights42.9%
- 15–29 min late14 flights4.0%
- 30–59 min late11 flights3.1%
- 1–2 hours late9 flights2.5%
- 2+ hours late8 flights2.3%
Scale runs 0% to 100%.
Share of 354 completed flights by arrival against schedule.
6 of 35 late departures made up the time and arrived on time, 17% of them. 13 flights left on time and still arrived late.
The worst days
Worst days for DL 459
The latest arrival of the period was on 25 February 2026, 5 hours 44 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The five worst days are spread across February, April, October and September, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 25 February 2026 | 5 hours 44 minutes | Late-arriving aircraft |
| 13 February 2026 | 5 hours 4 minutes | Carrier |
| 5 April 2026 | 4 hours 29 minutes | Extreme weather |
| 14 October 2025 | 4 hours 25 minutes | National Airspace System |
| 24 September 2025 | 4 hours 14 minutes | National Airspace System |
Delay causes
Why DL 459 runs late
National Airspace System accounts for 53% of the 3,532 delay minutes carriers reported here, and the remaining four split what is left.
- 53%National Airspace System
- 27%Carrier
- 12%Late-arriving aircraft
- 8%Extreme weather
53% 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 1,884 minutes out of 3,532, against a national NAS share of 21%. The split is drawn from 3,532 delay minutes reported on DL 459.
Cancellations sit at 2.47% against a national 1.89%, which is ordinary. Diversions add another 0.55%.
Connections and routes
What a delay on this flight costs
Badly late arrivals are rare here: only 4.8% 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 2,496 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.
Every one of the 365 flights under DL 459 in the data flew SEA to BOS. The number was not reused on any other city pair, which makes this a clean record of one route.
One caution: this is a thin sample. 365 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 DL 459
For a booking, read DL 459 as 88.1% on time with 2.47% cancelled over 365 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- SEA to BOS, every carrier and departure
- BOS to SEA, the return direction
- Alaska Airlines 306 on the same route75.6%
- Delta Air Lines 473 on the same route83.5%
- Alaska Airlines 460 on the same route81.8%
- Seattle-Tacoma International (SEA) delay statistics
- Boston Logan International (BOS) delay statistics
- Delta Air Lines on-time record
- Every Delta Air Lines flight number with a record
- The most and least reliable flight numbers in the US
- The best time of day to fly, according to 7.05 million flight records
A flight number here means Delta Air Lines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.
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.