Flight number record

DL 817

Delta Air Lines · Boston to Raleigh

Route: BOS → RDU
Departs: 19:45
Flights: 288
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 817, check with Delta Air Lines.

DL 817 earns an F, which is as low as this site's scale goes for a reason. Only 54.3% of flights arrive inside the 15-minute window, 23 points worse than the national rate of 77.6%. Late arrivals average an hour and a half. Treat any tight connection here as a coin flip. That rests on 288 flights, with a median arrival 7 minutes late.

The national on-time rate over the same period is 77.6%, so DL 817 runs 23 points behind the country as a whole. Across a thousand flights that is about 233 extra late arrivals.

On time

54.3%

Arrivals under 15 minutes late, of 280 completed flights

Avg delay

88 min

Across delayed arrivals only, not all flights

Cancelled

2.78%

National rate is 1.81%

1 hour+ late

26.4%

National rate is 8.1%

These figures cover 288 flights between July 2025 and June 2026. Beyond the headline rate, 26.4% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.

Schedule

When DL 817 flies

DL 817 flies BOS to RDU without a single fixed slot. Its most common scheduled departure was 19:45, used on 33 of 288 flights, with 20:05 (32 flights) and 19:49 (31 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 19:4533 flights11.5%
Departs 20:0532 flights11.1%
Departs 19:4931 flights10.8%

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 19:45 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and DL 817 runs 14 points worse at 54.3%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.

Against the route

DL 817 next to BOS to RDU

Every carrier on BOS to RDU combined arrived on time 76.3% of the time across 2,816 flights, so DL 817 is 22 points behind it. Delta flew 1,437 flights on the same city pair under all its flight numbers, including this one, and those ran 77.6% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 27 points.

DL 817 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 817thin sample	288	54.3%	88 min	2.78%	F
All Delta Air Lines on BOS–RDU	1,437	77.6%	86 min	2.44%	B
All carriers on BOS–RDU	2,816	76.3%	76 min	2.41%	B
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 817 quarter by quarter

DL 817 did not run the same all year. Its best quarter was Apr–Jun 2026 at 64.4% on time and its weakest Jul–Sep 2025 at 40.0%, a swing of 24 points on roughly 72 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 202577 flights40.0%
Oct–Dec 202563 flights48.4%
Jan–Mar 202673 flights64.3%
Apr–Jun 202675 flights64.4%

Scale runs 30% to 70%. Rows with fewer than 30 flights show a dash.

By weekday, DL 817 did best on Monday at 63.6% on time and worst on Thursday at 42.6%. Each day rests on about 41 flights, so a gap of 21 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 817 runs late

One category carries most of the weight here. Late-arriving aircraft accounts for 70% of the 11,000 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.

Late-arriving aircraft
70%
Carrier
20%
National Airspace System
8%
Extreme weather
2%

70% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 11,000 reported delay minutes here, that single category outweighs weather by 33 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 11,252 delay minutes reported on DL 817.

Cancellations run at 2.78%, against 1.81% nationally. That is roughly one flight in 40 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.

Connections and routes

What a delay on this flight costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 26.4% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.

The 612 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The same number turns up on three other city pairs in the data, including ATL to MEM (11), AGS to ATL (3) and ATL to AGS (3), but none flew often enough under DL 817 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to BOS to RDU only.

One caution: this is a thin sample. 288 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 817

For a booking, the cancellation rate is the figure to plan around on DL 817: 2.78% of its 288 scheduled flights did not operate. A late arrival costs an hour and a half, but a cancellation costs the day, so leave a later option open.

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