Flight number record

DL 423

Delta Air Lines · Atlanta to Salt Lake City

Route: ATL → SLC
Departs: 13:59
Flights: 365
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 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 77.6%. When something does go wrong the average delay runs about an hour. That rests on 365 flights, with a median arrival 5 minutes early.

Set against the rest of the country, DL 423's record is 8 points better than the US average of 77.6%. That gap is worth roughly 81 fewer late arrivals for every thousand flights.

On time

85.7%

Arrivals under 15 minutes late, of 363 completed flights

Avg delay

59 min

Across delayed arrivals only, not all flights

Cancelled

0.27%

National rate is 1.81%

1 hour+ late

3.0%

National rate is 8.1%

These figures cover 365 flights between July 2025 and June 2026. The median arrival is 5 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 423 flies

DL 423 flies ATL to SLC without a single fixed slot. Its most common scheduled departure was 13:59, used on 141 of 365 flights, with 13:55 (42 flights) and 13:50 (38 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 13:59141 flights38.6%
Departs 13:5542 flights11.5%
Departs 13:5038 flights10.4%

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 13:59 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.8%, and DL 423 runs 7 points better at 85.7%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

DL 423 next to ATL to SLC

Every carrier on ATL to SLC combined arrived on time 83.0% 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 83.0% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight beats by 4 points.

DL 423 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 423	365	85.7%	59 min	0.27%	A+
All Delta Air Lines on ATL–SLC	2,959	83.0%	60 min	0.41%	B+
All carriers on ATL–SLC	2,965	83.0%	60 min	0.40%	B+
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 423 quarter by quarter

Quarter by quarter DL 423 held fairly steady: 85.9% in Jul–Sep 2025, 87.0% in Oct–Dec 2025, 83.1% in Jan–Mar 2026 and 86.7% in Apr–Jun 2026. A spread of 4 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202592 flights85.9%
Oct–Dec 202592 flights87.0%
Jan–Mar 202690 flights83.1%
Apr–Jun 202691 flights86.7%

Scale runs 75% to 90%. Rows with fewer than 30 flights show a dash.

By weekday, DL 423 did best on Friday at 94.1% on time and worst on Sunday at 80.8%. Each day rests on about 52 flights, so a gap of 13 points is worth noticing but could still narrow in another year.

Delay causes

Why DL 423 runs late

One category carries most of the weight here. Carrier accounts for 66% of the 3,041 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
66%
National Airspace System
17%
Late-arriving aircraft
16%
Extreme weather
1%

The largest share of delay minutes, 66%, 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 2,000 of the 3,041 delay minutes reported here. The split is drawn from 3,041 delay minutes reported on DL 423.

Cancellations are rare at 0.27%, below the national 1.81% 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 3.0% 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.

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: 85.7% on time and 0.27% 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures