Flight number record

DL 1550

Delta Air Lines · Raleigh to Atlanta

Route: RDU → ATL
Departs: 17:15
Flights: 342
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 1550, check with Delta Air Lines.

DL 1550 earns a B. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 342 flights, with a median arrival 11 minutes early.

Set against the rest of the country, DL 1550's record is 7 points better than the US average of 77.6%. That gap is worth roughly 68 fewer late arrivals for every thousand flights.

On time

84.4%

Arrivals under 15 minutes late, of 334 completed flights

Avg delay

70 min

Across delayed arrivals only, not all flights

Cancelled

2.05%

National rate is 1.81%

1 hour+ late

5.7%

National rate is 8.1%

These figures cover 342 flights between July 2025 and June 2026. The median arrival is 11 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 1550 flies

DL 1550 flies RDU to ATL without a single fixed slot. Its most common scheduled departure was 17:15, used on 41 of 342 flights, with 17:25 (35 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 17:1541 flights12.0%
Departs 17:2535 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 17:15 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and DL 1550 runs 16 points better at 84.4%. 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 1550 next to RDU to ATL

Every carrier on RDU to ATL combined arrived on time 87.6% of the time across 4,618 flights, so DL 1550 is 3 points behind it. Delta flew 3,800 flights on the same city pair under all its flight numbers, including this one, and those ran 89.5% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight beats by 3 points.

DL 1550 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 1550thin sample	342	84.4%	70 min	2.05%	B
All Delta Air Lines on RDU–ATL	3,800	89.5%	86 min	1.37%	A
All carriers on RDU–ATL	4,618	87.6%	87 min	1.52%	A
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 1550 quarter by quarter

Quarter by quarter DL 1550 held fairly steady: 86.8% in Jul–Sep 2025, 86.8% in Oct–Dec 2025, 78.6% in Jan–Mar 2026 and 85.5% in Apr–Jun 2026. A spread of 8 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202592 flights86.8%
Oct–Dec 202578 flights86.8%
Jan–Mar 202686 flights78.6%
Apr–Jun 202686 flights85.5%

Scale runs 70% to 90%. Rows with fewer than 30 flights show a dash.

By weekday, DL 1550 did best on Wednesday at 92.0% on time and worst on Friday at 77.1%. Each day rests on about 49 flights, so a gap of 15 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 1550 runs late

One category carries most of the weight here. Late-arriving aircraft accounts for 46% of the 3,630 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
33%
Carrier
21%
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 3,630 reported delay minutes here, that single category outweighs weather by 46 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 3,630 delay minutes reported on DL 1550.

Cancellations sit at 2.05% against a national 1.81%, which is ordinary. Diversions add another 0.29%.

Connections and routes

What a delay on this flight costs

5.7% 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 a little over an hour, which a normal layover absorbs.

DL 1550 is not only a RDU to ATL flight. It also flew ATL to RDU (342 flights, 84.3% on time) often enough to be scored on its own. Airlines attach one number to several legs of an aircraft's day, and each leg keeps its own record here, so check which city pair is on your booking before reading a rate.

One caution: this is a thin sample. 342 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.

Other routes flown as DL 1550
Also flown as	Flights	On time	Avg delay	Cancelled	Grade
ATL to RDUthin sample	342	84.3%	52 min	1.46%	B

What to do with this

Booking DL 1550

For a booking, read DL 1550 as 84.4% on time with 2.05% cancelled over 342 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