Flight number record

DL 1251

Delta Air Lines · Atlanta to Tucson

Route: ATL → TUS
Departs: 20:55
Flights: 328
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 1251, check with Delta Air Lines.

DL 1251 lands a B, level with the national rate of 77.6%. Roughly one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 328 flights, with a median arrival 3 minutes early.

On time

77.7%

Arrivals under 15 minutes late, of 323 completed flights

Avg delay

56 min

Across delayed arrivals only, not all flights

Cancelled

1.52%

National rate is 1.81%

1 hour+ late

5.9%

National rate is 8.1%

These figures cover 328 flights between July 2025 and June 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.

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 20:59 (35 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 20:5549 flights14.9%
Departs 20:4036 flights11.0%
Departs 20:5935 flights10.7%

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 20:55 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.5%, and DL 1251 runs 7 points better at 77.7%. 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 1251 next to ATL to TUS

Every carrier on ATL to TUS combined arrived on time 83.1% of the time across 809 flights, so DL 1251 is 5 points behind it. Across its whole network Delta Air Lines managed 81.6%, which this flight trails by 4 points.

DL 1251 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 1251thin sample	328	77.7%	56 min	1.52%	B
All Delta Air Lines on ATL–TUS	809	83.1%	56 min	1.98%	B
All carriers on ATL–TUS	809	83.1%	56 min	1.98%	B
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	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 Oct–Dec 2025 at 72.2%, a swing of 17 points on roughly 82 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 202592 flights73.3%
Oct–Dec 202580 flights72.2%
Jan–Mar 202665 flights74.6%
Apr–Jun 202691 flights89.0%

Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.

By weekday, DL 1251 did best on Saturday at 89.7% on time and worst on Sunday at 72.9%. Each day rests on about 47 flights, so a gap of 17 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 1251 runs late

One category carries most of the weight here. Carrier accounts for 46% of the 4,028 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
46%
Late-arriving aircraft
31%
National Airspace System
17%
Extreme weather
6%

The largest share of delay minutes, 46%, 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 1,861 of the 4,028 delay minutes reported here. The split is drawn from 4,028 delay minutes reported on DL 1251.

Cancellations sit at 1.52% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

Connections and routes

What a delay on this flight costs

5.9% 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 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: 5 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.

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