Flight number record
DL 1581
Delta Air Lines · Denver to Salt Lake City
- Route
- DEN → SLC
- Departs
- 07:05
- Flights
- 360
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 1581, check with Delta Air Lines.
DL 1581 earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 14 points better than the national rate of 77.3%. When something does go wrong the average delay runs about 2.6 hours. That rests on 360 flights, with a median arrival 14 minutes early.
Set against the rest of the country, DL 1581's record is 14 points better than the US average of 77.3%. That gap is worth roughly 138 fewer late arrivals for every thousand flights.
Key figures
On time
91.1%
Arrivals under 15 minutes late, of 360 completed flights
Avg delay
153 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
1 hour+ late
5.6%
National rate is 8.3%
These figures cover 360 flights between September 2025 and August 2026. The median arrival is 14 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 1581 flies
DL 1581 flies DEN to SLC without a single fixed slot. Its most common scheduled departure was 07:05, used on 111 of 360 flights, with 07:00 (96 flights) and 07:10 (41 flights) next.
- Departs 07:05111 flights30.8%
- Departs 07:0096 flights26.7%
- Departs 07:1041 flights11.4%
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 07:05 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and DL 1581 runs level with that at 91.1%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
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Against the route
DL 1581 next to DEN to SLC
Every carrier on DEN to SLC combined arrived on time 78.2% of the time across 7,713 flights, so DL 1581 is 13 points ahead of it. Delta flew 1,698 flights on the same city pair under all its flight numbers, including this one, and those ran 82.0% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight beats by 10 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 1581thin sample | 360 | 91.1% | 153 min | 0.00% | A+ |
| All Delta Air Lines on DEN–SLC | 1,698 | 82.0% | 78 min | 0.35% | B+ |
| All carriers on DEN–SLC | 7,713 | 78.2% | 61 min | 0.35% | B+ |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 1581 quarter by quarter
Quarter by quarter DL 1581 held fairly steady: 96.7% in Jul–Sep 2025, 87.0% in Oct–Dec 2025, 90.0% in Jan–Mar 2026, 95.4% in Apr–Jun 2026 and 90.2% in Jul–Sep 2026. A spread of 10 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Jul–Sep 202530 flights96.7%
- Oct–Dec 202592 flights87.0%
- Jan–Mar 202690 flights90.0%
- Apr–Jun 202687 flights95.4%
- Jul–Sep 202661 flights90.2%
Scale runs 80% to 100%.
By weekday, DL 1581 ranged from 88.5% on Saturday to 96.2% on Thursday. With about 51 flights behind each day, a spread of 8 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late DL 1581 runs when it is late
DL 1581 often beats the schedule: 170 of 360 completed flights, 47%, arrived 15 minutes or more early. When DL 1581 is late it tends to be very late: 20 of its 32 late arrivals were an hour or more behind, and 14 were two hours or more.
- 15+ min early170 flights47.2%
- Within 15 min158 flights43.9%
- 15–29 min late6 flights1.7%
- 30–59 min late6 flights1.7%
- 1–2 hours late6 flights1.7%
- 2+ hours late14 flights3.9%
Scale runs 0% to 100%.
Share of 360 completed flights by arrival against schedule.
7 of 33 late departures made up the time and arrived on time, 21% of them. Only 6 left on time and still arrived late.
The worst days
Worst days for DL 1581
The latest arrival of the period was on 21 December 2025, 10 hours 2 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on five of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 21 December 2025 | 10 hours 2 minutes | Carrier |
| 7 October 2025 | 8 hours 28 minutes | Carrier |
| 25 February 2026 | 7 hours 42 minutes | Carrier |
| 10 March 2026 | 7 hours 18 minutes | Carrier |
| 21 March 2026 | 5 hours 15 minutes | Carrier |
Delay causes
Why DL 1581 runs late
Carrier accounts for 96% of the 4,900 delay minutes carriers reported here, and the remaining four split what is left.
- 96%Carrier
- 4%National Airspace System
The largest share of delay minutes, 96%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 4,689 of the 4,900 delay minutes reported here. The split is drawn from 4,900 delay minutes reported on DL 1581.
Cancellations are rare at 0.00%, below the national 1.89% and low enough to earn the plus on the grade. Almost no flights are called off; the risk here is arriving late, not not arriving.
Connections and routes
What a delay on this flight costs
5.6% 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 2.6 hours, which a normal layover absorbs.
Every one of the 360 flights under DL 1581 in the data flew DEN 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. 360 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 1581
For a booking, DL 1581 has one of the better records a US domestic flight can show: 91.1% on time and 0.00% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- DEN to SLC, every carrier and departure
- SLC to DEN, the return direction
- United Airlines 1963 on the same route79.9%
- Delta Air Lines 2663 on the same route69.1%
- SkyWest Airlines 5762 on the same route71.3%
- Frontier Airlines 4251 on the same route69.7%
- Delta Air Lines 2544 on the same route88.2%
- Delta Air Lines 1623 on the same route81.4%
- Denver International (DEN) delay statistics
- Salt Lake City International (SLC) 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.