Carrier route record

DLRDU→BOS

Delta Air Lines · Raleigh to Boston

Flights: 1,436
Period: July 2025 to June 2026
Share of route: 51%
Carriers: 4

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

Delta on RDU to BOS lands a B, 3 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That is a workable record, not a spotless one. That rests on 1,436 flights, with a median arrival 12 minutes early.

The US average over the same twelve months is 77.6%, so there is little to separate Delta on RDU to BOS from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

80.4%

Arrivals under 15 minutes late, of 1,400 completed flights

Avg delay

87 min

Across delayed arrivals only, not all flights

Cancelled

2.51%

National rate is 1.81%

Whole route

78.8%

Every carrier on RDU to BOS, 2,815 flights

These figures cover 1,436 flights between July 2025 and June 2026. Beyond the headline rate, 10.3% 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.

Carrier by carrier

Delta against every carrier on RDU to BOS

Delta flew 1,436 of the 2,815 flights on RDU to BOS, most of the route. Its 80.4% on time is 2 points better than the route as a whole, which runs 78.8%. Ranked by on-time rate it is number two of four carriers on the route, where the range runs from Frontier at 80.5% to JetBlue at 76.4%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.

On-time performance by carrier on RDU to BOS
Airline	Flights	On time	Avg delay	Cancelled	Grade
Frontier Airlinesthin sample	159	80.5%	56 min	0.00%	B+
Delta Air Lines (this page)	1,436	80.4%	87 min	2.51%	B
Republic Airwaysthin sample	137	80.0%	94 min	5.11%	B−
JetBlue Airways	1,083	76.4%	79 min	2.77%	B

Flight by flight

Delta flight numbers on RDU to BOS

Departure window

When Delta runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 28 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am346 flights93.1%
8am–11am277 flights90.0%
11am–2pm292 flights74.7%
2pm–5pm219 flights66.1%
5pm–8pm125 flights84.7%
8pm–5am177 flights65.5%

Scale runs 55% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 93.1% of the time, against 65.5% for the overnight window. That is 28 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 346 flights scheduled in it.

Across the year

Delta on RDU to BOS through the year

Darker means more delays. Figures are on-time percentages.February best, September worst

Delays peak in September, when the on-time rate falls to 66.9%. February is the strongest month at 90.4%. Moving a flexible trip across that boundary buys 24 points. October was the busiest month here, with 142 flights.

Across the week, Saturday is the strongest day at 89.3% on time and Sunday the weakest at 76.4%. 13 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Delta runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 46% of the 24,000 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
46%
National Airspace System
39%
Carrier
13%
Extreme weather
1%

46% 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 24,000 reported delay minutes here, that single category outweighs weather by 44 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 24,003 reported delay minutes.

39% 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 9,445 minutes out of 24,000, against a national NAS share of 21%.

Cancellations run at 2.51%, 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 stage length

What a delay here costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.3% 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 return leg runs 77.6% on time across 1,437 flights, within 3 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

The sample behind these figures is 1,436 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.

What to do with this

Booking Delta on RDU to BOS

Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 90.4% on time and September 66.9%, a swing of 24 points. If the dates move at all, move them out of September before you think about anything else. 1,400 completed flights over 12 months sit behind that.

Where to go next

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