Flight number record

DL 1721

Delta Air Lines · Mobile to Atlanta

Route: MOB → ATL
Departs: 06:00
Flights: 277
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 1721, check with Delta Air Lines.

DL 1721 earns an A. Nearly every flight arrives inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 16 points better than the national rate of 77.6%. When something does go wrong the average delay runs close to two hours. That rests on 277 flights, with a median arrival 16 minutes early.

Set against the rest of the country, DL 1721's record is 16 points better than the US average of 77.6%. That gap is worth roughly 157 fewer late arrivals for every thousand flights.

On time

93.3%

Arrivals under 15 minutes late, of 269 completed flights

Avg delay

119 min

Across delayed arrivals only, not all flights

Cancelled

2.89%

National rate is 1.81%

1 hour+ late

4.5%

National rate is 8.1%

These figures cover 277 flights between July 2025 and June 2026. The median arrival is 16 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 1721 flies

DL 1721 flies MOB to ATL without a single fixed slot. Its most common scheduled departure was 06:00, used on 148 of 277 flights, with 06:15 (36 flights) and 06:09 (35 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 06:00148 flights53.4%
Departs 06:1536 flights13.0%
Departs 06:0935 flights12.6%

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 06:00 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and DL 1721 runs 4 points better at 93.3%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

Against the route

DL 1721 next to MOB to ATL

Every carrier on MOB to ATL combined arrived on time 83.6% of the time across 930 flights, so DL 1721 is 10 points ahead of it. Delta flew 755 flights on the same city pair under all its flight numbers, including this one, and those ran 86.5% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight beats by 12 points.

DL 1721 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 1721thin sample	277	93.3%	119 min	2.89%	A
All Delta Air Lines on MOB–ATL	755	86.5%	80 min	2.38%	A
All carriers on MOB–ATL	930	83.6%	84 min	2.26%	B
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 1721 quarter by quarter

Quarter by quarter DL 1721 held fairly steady: 94.6% in Jul–Sep 2025, 97.4% in Oct–Dec 2025, 91.5% in Jan–Mar 2026 and 91.1% in Apr–Jun 2026. A spread of 6 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202592 flights94.6%
Oct–Dec 202539 flights97.4%
Jan–Mar 202686 flights91.5%
Apr–Jun 202660 flights91.1%

Scale runs 85% to 100%. Rows with fewer than 30 flights show a dash.

By weekday, DL 1721 did best on Sunday at 100.0% on time and worst on Monday at 81.6%. Each day rests on about 40 flights, so a gap of 18 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 1721 runs late

One category carries most of the weight here. Carrier accounts for 69% of the 2,139 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
69%
Late-arriving aircraft
17%
National Airspace System
10%
Extreme weather
4%

The largest share of delay minutes, 69%, 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 1,480 of the 2,139 delay minutes reported here. The split is drawn from 2,139 delay minutes reported on DL 1721.

Cancellations run at 2.89%, against 1.81% nationally. That is roughly one flight in 30 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

Badly late arrivals are rare here: only 4.5% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

The same number turns up on two other city pairs in the data, including SJU to BOS (16) and BOS to LGA (1), but none flew often enough under DL 1721 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to MOB to ATL only.

One caution: this is a thin sample. 277 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 1721

For a booking, the cancellation rate is the figure to plan around on DL 1721: 2.89% of its 277 scheduled flights did not operate. A late arrival costs close to two hours, 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