Flight number record
DL 1251
Delta Air Lines · Atlanta to Tucson
- Route
- ATL → TUS
- Departs
- 20:55
- Flights
- 328
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 1251, check with Delta Air Lines.
DL 1251 lands a B+, about a point worse than the national rate of 77.3%. About one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 328 flights, with a median arrival 3 minutes early.
Key figures
On time
76.2%
Arrivals under 15 minutes late, of 324 completed flights
Avg delay
60 min
Across delayed arrivals only, not all flights
Cancelled
0.91%
National rate is 1.89%
1 hour+ late
7.1%
National rate is 8.3%
These figures cover 328 flights between September 2025 and August 2026. The median arrival is 3 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.
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Schedule
When DL 1251 flies
DL 1251 flies ATL to TUS without a single fixed slot. Its most common scheduled departure was 20:55, used on 49 of 328 flights, with 20:40 (36 flights) and 21:40 (34 flights) next.
- Departs 20:5549 flights14.9%
- Departs 20:4036 flights11.0%
- Departs 21:4034 flights10.4%
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 20:55 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.1%, and DL 1251 runs 6 points better at 76.2%. 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 1251 next to ATL to TUS
Every carrier on ATL to TUS combined arrived on time 82.4% of the time across 809 flights, so DL 1251 is 6 points behind it. Across its whole network Delta Air Lines managed 81.1%, which this flight trails by 5 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 1251thin sample | 328 | 76.2% | 60 min | 0.91% | B+ |
| All Delta Air Lines on ATL–TUS | 809 | 82.4% | 57 min | 1.73% | B |
| All carriers on ATL–TUS | 809 | 82.4% | 57 min | 1.73% | B |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 1251 quarter by quarter
DL 1251 did not run the same all year. Its best quarter was Apr–Jun 2026 at 89.0% on time and its weakest Jul–Sep 2026 at 59.0%, a swing of 30 points on roughly 66 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 202530 flights86.7%
- Oct–Dec 202580 flights72.2%
- Jan–Mar 202665 flights74.6%
- Apr–Jun 202691 flights89.0%
- Jul–Sep 202662 flights59.0%
Scale runs 50% to 95%.
By weekday, DL 1251 did best on Saturday at 82.1% on time and worst on Sunday at 68.8%. Each day rests on about 47 flights, so a gap of 13 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 1251 runs when it is late
DL 1251 often beats the schedule: 82 of 324 completed flights, 25%, arrived 15 minutes or more early. The 77 late arrivals split 33 under half an hour, 21 between 30 and 60 minutes, and 23 an hour or more.
- 15+ min early82 flights25.3%
- Within 15 min165 flights50.9%
- 15–29 min late33 flights10.2%
- 30–59 min late21 flights6.5%
- 1–2 hours late13 flights4.0%
- 2+ hours late10 flights3.1%
Scale runs 0% to 100%.
Share of 324 completed flights by arrival against schedule.
16 of 76 late departures made up the time and arrived on time, 21% of them. In the other direction, 17 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at TUS.
The worst days
Worst days for DL 1251
The latest arrival of the period was on 30 October 2025, 3 hours 47 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on four of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 30 October 2025 | 3 hours 47 minutes | Late-arriving aircraft |
| 16 March 2026 | 3 hours 45 minutes | Late-arriving aircraft |
| 7 December 2025 | 3 hours 40 minutes | Late-arriving aircraft |
| 11 July 2026 | 3 hours 32 minutes | Late-arriving aircraft |
| 18 July 2026 | 3 hours 18 minutes | Carrier |
Delay causes
Why DL 1251 runs late
Carrier accounts for 48% of the 4,616 delay minutes carriers reported here, and the remaining four split what is left.
- 48%Carrier
- 38%Late-arriving aircraft
- 12%National Airspace System
- 1%Extreme weather
38% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 4,616 reported delay minutes here, that single category outweighs weather by 34 to one. The split is drawn from 4,616 delay minutes reported on DL 1251.
Cancellations sit at 0.91% against a national 1.89%, which is ordinary. Diversions add another 0.30%.
Connections and routes
What a delay on this flight costs
7.1% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
At 1,541 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The same number turns up on two other city pairs in the data, including ATL to GSP (16) and GSP to ATL (16), but none flew often enough under DL 1251 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to ATL to TUS only.
One caution: this is a thin sample. 328 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 1251
For a booking, DL 1251 is one of the weaker ways to fly ATL to TUS: 6 points below the route as a whole. If the schedule allows, compare it with the other departures listed on the route page before settling on this one.
Related
Where to go next
- ATL to TUS, every carrier and departure
- TUS to ATL, the return direction
- Hartsfield-Jackson Atlanta International (ATL) delay statistics
- Delta Air Lines on-time record
- Every Delta Air Lines flight number with a record
- The most and least reliable flight numbers in the US
- Why the first flight of the morning is statistically safest
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 ; recomputed monthly. How this data is collected.