Flight number record

DL 300

Delta Air Lines · Atlanta to Boston

Route: ATL → BOS
Departs: 19:59
Flights: 333
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 300, check with Delta Air Lines.

DL 300 sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 9 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 333 flights, with a median arrival 2 minutes early.

The national on-time rate over the same period is 77.6%, so DL 300 runs 9 points behind the country as a whole. Across a thousand flights that is about 91 extra late arrivals.

On time

68.5%

Arrivals under 15 minutes late, of 324 completed flights

Avg delay

60 min

Across delayed arrivals only, not all flights

Cancelled

2.70%

National rate is 1.81%

1 hour+ late

10.8%

National rate is 8.1%

These figures cover 333 flights between July 2025 and June 2026. Beyond the headline rate, 10.8% 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 300 flies

DL 300 flies ATL to BOS without a single fixed slot. Its most common scheduled departure was 19:59, used on 102 of 333 flights, with 20:30 (55 flights) and 20:40 (34 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 19:59102 flights30.6%
Departs 20:3055 flights16.5%
Departs 20:4034 flights10.2%

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 19:59 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and DL 300 runs level with that at 68.5%. 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 300 next to ATL to BOS

Every carrier on ATL to BOS combined arrived on time 74.5% of the time across 4,935 flights, so DL 300 is 6 points behind it. Delta flew 3,666 flights on the same city pair under all its flight numbers, including this one, and those ran 76.2% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 13 points.

DL 300 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 300thin sample	333	68.5%	60 min	2.70%	C
All Delta Air Lines on ATL–BOS	3,666	76.2%	59 min	1.72%	B
All carriers on ATL–BOS	4,935	74.5%	63 min	1.95%	C
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 300 quarter by quarter

DL 300 did not run the same all year. Its best quarter was Apr–Jun 2026 at 74.6% on time and its weakest Jul–Sep 2025 at 61.8%, a swing of 13 points on roughly 83 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 flights61.8%
Oct–Dec 202592 flights73.9%
Jan–Mar 202689 flights65.5%
Apr–Jun 202660 flights74.6%

Scale runs 55% to 80%. Rows with fewer than 30 flights show a dash.

By weekday, DL 300 did best on Saturday at 78.7% on time and worst on Thursday at 57.8%. Each day rests on about 48 flights, so a gap of 21 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 300 runs late

One category carries most of the weight here. Carrier accounts for 42% of the 6,130 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.

Carrier
42%
Late-arriving aircraft
28%
National Airspace System
26%
Extreme weather
4%

The largest share of delay minutes, 42%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 2,575 of the 6,130 delay minutes reported here. The split is drawn from 6,130 delay minutes reported on DL 300.

Cancellations run at 2.70%, against 1.81% nationally. That is about 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. 10.8% 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 946 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.

Every one of the 333 flights under DL 300 in the data flew ATL 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. 333 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 300

For a booking, the cancellation rate is the figure to plan around on DL 300: 2.70% of its 333 scheduled flights did not operate. A late arrival costs about an hour, 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