Flight number record

DL 300

Delta Air Lines · Atlanta to Boston

Route: ATL → BOS
Departs: 19:59
Flights: 298
Period: September 2025 to August 2026

Historical statistics for September 2025 to August 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 77.3%. The late ones land about an hour behind schedule. That rests on 298 flights, with a median arrival 2 minutes early.

The national on-time rate over the same period is 77.3%, so DL 300 runs 9 points behind the country as a whole. Across a thousand flights that is about 85 extra late arrivals.

On time

68.8%

Arrivals under 15 minutes late, of 292 completed flights

Avg delay

62 min

Across delayed arrivals only, not all flights

Cancelled

2.01%

National rate is 1.89%

1 hour+ late

10.3%

National rate is 8.3%

These figures cover 298 flights between September 2025 and August 2026. Beyond the headline rate, 10.3% of arrivals land a full hour or more behind schedule, against 8.3% nationally.

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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 61 of 298 flights, with 20:30 (38 flights) and 20:40 (34 flights) next.

Departs 19:5961 flights20.5%
Departs 20:3038 flights12.8%
Departs 20:4034 flights11.4%

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 19:59 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.0%, and DL 300 runs level with that at 68.8%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.

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Against the route

DL 300 next to ATL to BOS

Every carrier on ATL to BOS combined arrived on time 72.8% of the time across 5,054 flights, so DL 300 is 4 points behind it. Delta flew 3,731 flights on the same city pair under all its flight numbers, including this one, and those ran 74.4% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight trails by 12 points.

DL 300 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 300thin sample	298	68.8%	62 min	2.01%	C
All Delta Air Lines on ATL–BOS	3,731	74.4%	61 min	1.82%	C
All carriers on ATL–BOS	5,054	72.8%	66 min	2.30%	C
Delta Air Lines, whole network	1,039,517	81.1%	71 min	1.74%	B

Across the year

DL 300 quarter by quarter

Quarter by quarter DL 300 held fairly steady: 73.3% in Jul–Sep 2025, 73.9% in Oct–Dec 2025, 65.5% in Jan–Mar 2026 and 74.6% in Apr–Jun 2026. A spread of 9 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202530 flights73.3%
Oct–Dec 202592 flights73.9%
Jan–Mar 202689 flights65.5%
Apr–Jun 202660 flights74.6%
Jul–Sep 202627 flights—

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

By weekday, DL 300 did best on Wednesday at 79.5% on time and worst on Thursday at 57.1%. Each day rests on about 43 flights, so a gap of 22 points is worth noticing but could still narrow in another year.

Arrival by arrival

How late DL 300 runs when it is late

The 91 late arrivals split 32 under half an hour, 29 between 30 and 60 minutes, and 30 an hour or more.

15+ min early52 flights17.8%
Within 15 min149 flights51.0%
15–29 min late32 flights11.0%
30–59 min late29 flights9.9%
1–2 hours late18 flights6.2%
2+ hours late12 flights4.1%

Scale runs 0% to 100%.

Share of 292 completed flights by arrival against schedule.

25 of 109 late departures made up the time and arrived on time, 23% of them. 7 flights left on time and still arrived late.

The worst days

Worst days for DL 300

The latest arrival of the period was on 16 March 2026, 6 hours 7 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.

The latest arrivals of DL 300 in the period
Date	Arrived late by	Largest filed cause
16 March 2026	6 hours 7 minutes	Carrier
12 July 2026	4 hours 36 minutes	Late-arriving aircraft
30 September 2025	3 hours 47 minutes	Carrier
17 March 2026	3 hours 23 minutes	Carrier
17 July 2026	3 hours 8 minutes	Late-arriving aircraft

Delay causes

Why DL 300 runs late

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 5,668 reported delay minutes.

Carrier
37%
Late-arriving aircraft
33%
National Airspace System
28%
Extreme weather
2%

The largest share of delay minutes, 37%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,116 of the 5,668 delay minutes reported here. The split is drawn from 5,668 delay minutes reported on DL 300.

Cancellations sit at 2.01% against a national 1.89%, which is ordinary. Diversions add another 0.00%.

Connections and routes

What a delay on this flight costs

10.3% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection 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.

Every one of the 298 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. 298 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, read DL 300 as 68.8% on time with 2.01% cancelled over 298 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, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures