Flight number record

DL 423

Delta Air Lines · Atlanta to Salt Lake City

Route: ATL → SLC
Departs: 13:59
Flights: 365
Period: September 2025 to August 2026

Historical statistics for September 2025 to August 2026, not live status. For today’s DL 423, check with Delta Air Lines.

DL 423 earns an A+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 8 points better than the national rate of 77.3%. When something does go wrong the average delay runs roughly 45 minutes. That rests on 365 flights, with a median arrival 6 minutes early.

Set against the rest of the country, DL 423's record is 8 points better than the US average of 77.3%. That gap is worth roughly 83 fewer late arrivals for every thousand flights.

On time

85.6%

Arrivals under 15 minutes late, of 362 completed flights

Avg delay

47 min

Across delayed arrivals only, not all flights

Cancelled

0.55%

National rate is 1.89%

1 hour+ late

2.5%

National rate is 8.3%

These figures cover 365 flights between September 2025 and August 2026. The median arrival is 6 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 423 flies

DL 423 flies ATL to SLC without a single fixed slot. Its most common scheduled departure was 13:59, used on 121 of 365 flights, with 13:50 (68 flights) and 13:55 (67 flights) next.

Departs 13:59121 flights33.2%
Departs 13:5068 flights18.6%
Departs 13:5567 flights18.4%

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 13:59 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and DL 423 runs 7 points better at 85.6%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

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Against the route

DL 423 next to ATL to SLC

Every carrier on ATL to SLC combined arrived on time 82.7% of the time across 2,965 flights, so DL 423 is 3 points ahead of it. Delta flew 2,959 flights on the same city pair under all its flight numbers, including this one, and those ran 82.7% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight beats by 5 points.

DL 423 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 423	365	85.6%	47 min	0.55%	A+
All Delta Air Lines on ATL–SLC	2,959	82.7%	60 min	0.44%	B+
All carriers on ATL–SLC	2,965	82.7%	60 min	0.44%	B+
Delta Air Lines, whole network	1,039,517	81.1%	71 min	1.74%	B

Across the year

DL 423 quarter by quarter

DL 423 did not run the same all year. Its best quarter was Jul–Sep 2025 at 96.7% on time and its weakest Jul–Sep 2026 at 80.3%, a swing of 16 points on roughly 73 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 flights96.7%
Oct–Dec 202592 flights87.0%
Jan–Mar 202690 flights83.1%
Apr–Jun 202691 flights86.7%
Jul–Sep 202662 flights80.3%

Scale runs 70% to 100%.

By weekday, DL 423 ranged from 82.4% on Sunday to 88.5% on Saturday. With about 52 flights behind each day, a spread of 6 points is inside normal variation, so the day you fly is not worth changing for this flight.

Arrival by arrival

How late DL 423 runs when it is late

DL 423 often beats the schedule: 95 of 362 completed flights, 26%, arrived 15 minutes or more early. The 52 late arrivals split 24 under half an hour, 19 between 30 and 60 minutes, and 9 an hour or more.

15+ min early95 flights26.2%
Within 15 min215 flights59.4%
15–29 min late24 flights6.6%
30–59 min late19 flights5.2%
1–2 hours late4 flights1.1%
2+ hours late5 flights1.4%

Scale runs 0% to 100%.

Share of 362 completed flights by arrival against schedule.

Time lost at the gate mostly stays lost. Of 36 departures that left 15 minutes late or more, only 4 made it up before arrival. In the other direction, 20 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 SLC.

The worst days

Worst days for DL 423

The latest arrival of the period was on 21 May 2026, 4 hours 5 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on four of the five worst days.

The latest arrivals of DL 423 in the period
Date	Arrived late by	Largest filed cause
21 May 2026	4 hours 5 minutes	Carrier
17 March 2026	2 hours 45 minutes	Carrier
7 June 2026	2 hours 24 minutes	Carrier
7 December 2025	2 hours 6 minutes	Late-arriving aircraft
10 January 2026	2 hours 5 minutes	Carrier

Delay causes

Why DL 423 runs late

Carrier accounts for 52% of the 2,417 delay minutes carriers reported here, and the remaining four split what is left.

Carrier
52%
National Airspace System
28%
Late-arriving aircraft
18%
Extreme weather
3%

The largest share of delay minutes, 52%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,249 of the 2,417 delay minutes reported here. The split is drawn from 2,417 delay minutes reported on DL 423.

Cancellations are rare at 0.55%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

Connections and routes

What a delay on this flight costs

Badly late arrivals are rare here: only 2.5% land an hour or more behind schedule, against 8.3% 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.

At 1,590 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.

Every one of the 365 flights under DL 423 in the data flew ATL to SLC. The number was not reused on any other city pair, which makes this a clean record of one route.

One caution: this is a thin sample. 365 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 423

For a booking, DL 423 has one of the better records a US domestic flight can show: 85.6% on time and 0.55% cancelled. That is a base rate, not a promise about any single 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, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures