Flight number record
DL 1623
Delta Air Lines · Salt Lake City to Denver
- Route
- SLC → DEN
- Departs
- 13:20
- Flights
- 359
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 1623, check with Delta Air Lines.
DL 1623 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 about 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 8 points better than the US average of 77.3%. That gap is worth roughly 80 fewer late arrivals for every thousand flights.
Key figures
On time
85.3%
Arrivals under 15 minutes late, of 353 completed flights
Avg delay
66 min
Across delayed arrivals only, not all flights
Cancelled
0.56%
National rate is 1.89%
1 hour+ late
5.1%
National rate is 8.3%
These figures cover 359 flights between September 2025 and August 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.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 174 of 359 flights, with 13:30 (64 flights) and 13:40 (36 flights) next.
- Departs 13:20174 flights48.5%
- Departs 13:3064 flights17.8%
- Departs 13:4036 flights10.0%
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 13:20 departure sits in the 11am–2pm window. Across every US flight scheduled in that window the on-time rate is 78.3%, and DL 1623 runs 7 points better at 85.3%. Midday slots inherit some of the morning's delays without yet carrying the full weight of the evening's.
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Against the route
DL 1623 next to SLC to DEN
Every carrier on SLC to DEN combined arrived on time 79.0% of the time across 7,709 flights, so DL 1623 is 6 points ahead of it. Delta flew 1,697 flights on the same city pair under all its flight numbers, including this one, and those ran 79.8% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight beats by 4 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 1623thin sample | 359 | 85.3% | 66 min | 0.56% | A+ |
| All Delta Air Lines on SLC–DEN | 1,697 | 79.8% | 64 min | 0.18% | B+ |
| All carriers on SLC–DEN | 7,709 | 79.0% | 61 min | 0.51% | B+ |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 1623 quarter by quarter
DL 1623 did not run the same all year. Its best quarter was Jul–Sep 2025 at 90.0% on time and its weakest Jul–Sep 2026 at 77.6%, a swing of 12 points on roughly 72 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 flights90.0%
- Oct–Dec 202589 flights86.4%
- Jan–Mar 202688 flights86.2%
- Apr–Jun 202691 flights86.7%
- Jul–Sep 202661 flights77.6%
Scale runs 70% to 95%.
By weekday, DL 1623 ranged from 82.4% on Wednesday to 88.0% on Friday. With about 51 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 1623 runs when it is late
The 52 late arrivals split 22 under half an hour, 12 between 30 and 60 minutes, and 18 an hour or more.
- 15+ min early80 flights22.7%
- Within 15 min221 flights62.6%
- 15–29 min late22 flights6.2%
- 30–59 min late12 flights3.4%
- 1–2 hours late9 flights2.5%
- 2+ hours late9 flights2.5%
Scale runs 0% to 100%.
Share of 353 completed flights by arrival against schedule.
10 of 50 late departures made up the time and arrived on time, 20% of them. 12 flights left on time and still arrived late.
The worst days
Worst days for DL 1623
The latest arrival of the period was on 18 February 2026, 5 hours 41 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 18 February 2026 | 5 hours 41 minutes | Carrier |
| 19 April 2026 | 5 hours 15 minutes | Carrier |
| 2 April 2026 | 3 hours 49 minutes | Carrier |
| 24 June 2026 | 3 hours 42 minutes | National Airspace System |
| 23 December 2025 | 3 hours 40 minutes | Late-arriving aircraft |
Delay causes
Why DL 1623 runs late
Carrier accounts for 52% of the 3,454 delay minutes carriers reported here, and the remaining four split what is left.
- 52%Carrier
- 33%National Airspace System
- 14%Late-arriving aircraft
- 2%Extreme weather
33% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 1,124 minutes out of 3,454, against a national NAS share of 21%. The split is drawn from 3,454 delay minutes reported on DL 1623.
Cancellations are rare at 0.56%, 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
5.1% 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.
DL 1623 is not only a SLC to DEN flight. It also flew DEN to SLC (271 flights, 81.4% 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.
| Also flown as | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DEN to SLCthin sample | 271 | 81.4% | 77 min | 0.74% | B+ |
What to do with this
Booking DL 1623
For a booking, DL 1623 has one of the better records a US domestic flight can show: 85.3% on time and 0.56% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- SLC to DEN, every carrier and departure
- DEN to SLC, the return direction
- Frontier Airlines 3862 on the same route79.6%
- Delta Air Lines 1586 on the same route68.3%
- Delta Air Lines 1553 on the same route78.9%
- SkyWest Airlines 4720 on the same route90.7%
- Delta Air Lines 1667 on the same route79.7%
- SkyWest Airlines 5683 on the same route93.9%
- Salt Lake City International (SLC) delay statistics
- Denver International (DEN) 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
- Worst months to fly in the US, ranked by the data
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.