Flight number record

DL 459

Delta Air Lines · Seattle to Boston

Route: SEA → BOS
Departs: 07:45
Flights: 365
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 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 77.6%. When something does go wrong the average delay runs an hour and a half. That rests on 365 flights, with a median arrival 14 minutes early.

Set against the rest of the country, DL 459's record is 11 points better than the US average of 77.6%. That gap is worth roughly 112 fewer late arrivals for every thousand flights.

On time

88.8%

Arrivals under 15 minutes late, of 356 completed flights

Avg delay

93 min

Across delayed arrivals only, not all flights

Cancelled

1.92%

National rate is 1.81%

1 hour+ late

5.3%

National rate is 8.1%

These figures cover 365 flights between July 2025 and June 2026. The median arrival is 14 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.

Schedule

When DL 459 flies

DL 459 flies SEA to BOS without a single fixed slot. Its most common scheduled departure was 07:45, used on 66 of 365 flights, with 07:50 (65 flights) and 07:15 (55 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 07:4566 flights18.1%
Departs 07:5065 flights17.8%
Departs 07:1555 flights15.1%

Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.

Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.

A 07:45 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 88.8%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

Against the route

DL 459 next to SEA to BOS

Every carrier on SEA to BOS combined arrived on time 74.5% of the time across 2,459 flights, so DL 459 is 14 points ahead of it. Delta flew 1,005 flights on the same city pair under all its flight numbers, including this one, and those ran 81.2% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight beats by 7 points.

DL 459 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 459	365	88.8%	93 min	1.92%	A
All Delta Air Lines on SEA–BOS	1,005	81.2%	68 min	1.49%	B
All carriers on SEA–BOS	2,459	74.5%	68 min	1.14%	C
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	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 Oct–Dec 2025 at 81.1%, a swing of 13 points on roughly 91 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 202592 flights90.1%
Oct–Dec 202592 flights81.1%
Jan–Mar 202690 flights89.5%
Apr–Jun 202691 flights94.4%

Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.

By weekday, DL 459 ranged from 84.3% on Wednesday to 94.0% 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.

Delay causes

Why DL 459 runs late

One category carries most of the weight here. National Airspace System accounts for 49% of the 3,733 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

National Airspace System
49%
Carrier
32%
Late-arriving aircraft
11%
Extreme weather
7%

49% 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 1,838 minutes out of 3,733, against a national NAS share of 21%. The split is drawn from 3,733 delay minutes reported on DL 459.

Cancellations sit at 1.92% against a national 1.81%, which is ordinary. Diversions add another 0.55%.

Connections and routes

What a delay on this flight costs

5.3% 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 an hour and a half, which a normal layover absorbs.

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 88.8% on time with 1.92% cancelled over 365 flights. Those are rates from the past twelve months, not a forecast for any particular day.

Where to go next

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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures