Flight number record

DL 1623

Delta Air Lines · Salt Lake City to Denver

Route: SLC → DEN
Departs: 13:20
Flights: 359
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s DL 1623, check with Delta Air Lines.

DL 1623 earns a B+. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 359 flights, with a median arrival 7 minutes early.

Set against the rest of the country, DL 1623's record is 7 points better than the US average of 77.6%. That gap is worth roughly 65 fewer late arrivals for every thousand flights.

On time

84.1%

Arrivals under 15 minutes late, of 353 completed flights

Avg delay

69 min

Across delayed arrivals only, not all flights

Cancelled

0.84%

National rate is 1.81%

1 hour+ late

5.7%

National rate is 8.1%

These figures cover 359 flights between July 2025 and June 2026. The median arrival is 7 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 1623 flies

DL 1623 flies SLC to DEN without a single fixed slot. Its most common scheduled departure was 13:20, used on 162 of 359 flights, with 13:30 (99 flights) and 13:40 (36 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 13:20162 flights45.1%
Departs 13:3099 flights27.6%
Departs 13:4036 flights10.0%

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 13:20 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.8%, and DL 1623 runs 5 points better at 84.1%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.

Against the route

DL 1623 next to SLC to DEN

Every carrier on SLC to DEN combined arrived on time 77.8% of the time across 7,757 flights, so DL 1623 is 6 points ahead of it. Delta flew 1,690 flights on the same city pair under all its flight numbers, including this one, and those ran 79.4% on time. Across its whole network Delta Air Lines managed 81.6%, which this flight beats by 3 points.

DL 1623 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
DL 1623thin sample	359	84.1%	69 min	0.84%	B+
All Delta Air Lines on SLC–DEN	1,690	79.4%	64 min	0.24%	B+
All carriers on SLC–DEN	7,757	77.8%	61 min	0.55%	B+
Delta Air Lines, whole network	1,038,570	81.6%	71 min	1.62%	B

Across the year

DL 1623 quarter by quarter

Quarter by quarter DL 1623 held fairly steady: 77.3% in Jul–Sep 2025, 86.4% in Oct–Dec 2025, 86.2% in Jan–Mar 2026 and 86.7% in Apr–Jun 2026. A spread of 9 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202591 flights77.3%
Oct–Dec 202589 flights86.4%
Jan–Mar 202688 flights86.2%
Apr–Jun 202691 flights86.7%

Scale runs 70% to 90%. Rows with fewer than 30 flights show a dash.

By weekday, DL 1623 ranged from 78.8% on Wednesday to 88.2% on Sunday. With about 51 flights behind each day, a spread of 9 points is inside normal variation, so the day you fly is not worth changing for this flight.

Delay causes

Why DL 1623 runs late

One category carries most of the weight here. Carrier accounts for 53% of the 3,885 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
53%
National Airspace System
32%
Late-arriving aircraft
13%
Extreme weather
2%

The largest share of delay minutes, 53%, 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 2,077 of the 3,885 delay minutes reported here. The split is drawn from 3,885 delay minutes reported on DL 1623.

Cancellations are rare at 0.84%, 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

5.7% 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 a little over an hour, which a normal layover absorbs.

DL 1623 is not only a SLC to DEN flight. It also flew DEN to SLC (272 flights, 83.6% on time) often enough to be scored on its own. Airlines attach one number to several legs of an aircraft's day, and each leg keeps its own record here, so check which city pair is on your booking before reading a rate.

One caution: this is a thin sample. 359 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.

Other routes flown as DL 1623
Also flown as	Flights	On time	Avg delay	Cancelled	Grade
DEN to SLCthin sample	272	83.6%	88 min	1.10%	B

What to do with this

Booking DL 1623

For a booking, read DL 1623 as 84.1% on time with 0.84% cancelled over 359 flights. Those are rates from the past twelve months, not a forecast for any particular 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