Flight number record
DL 1535
Delta Air Lines · Phoenix to Salt Lake City
- Route
- PHX → SLC
- Departs
- 06:00
- Flights
- 365
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 1535, check with Delta Air Lines.
DL 1535 earns an A+. Nearly every flight arrives inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 20 points better than the national rate of 77.3%. When something does go wrong the average delay runs about 2.4 hours. That rests on 365 flights, with a median arrival 14 minutes early.
Set against the rest of the country, DL 1535's record is 20 points better than the US average of 77.3%. That gap is worth roughly 200 fewer late arrivals for every thousand flights.
Key figures
On time
97.3%
Arrivals under 15 minutes late, of 365 completed flights
Avg delay
143 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
1 hour+ late
1.4%
National rate is 8.3%
These figures cover 365 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 1535 flies
DL 1535 flies PHX to SLC without a single fixed slot. Its most common scheduled departure was 06:00, used on 156 of 365 flights, with 06:55 (62 flights) and 06:05 (55 flights) next.
- Departs 06:00156 flights42.7%
- Departs 06:5562 flights17.0%
- Departs 06:0555 flights15.1%
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 06:00 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and DL 1535 runs 8 points better at 97.3%. 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 1535 next to PHX to SLC
Every carrier on PHX to SLC combined arrived on time 83.0% of the time across 5,779 flights, so DL 1535 is 14 points ahead of it. Delta flew 1,706 flights on the same city pair under all its flight numbers, including this one, and those ran 90.1% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight beats by 16 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 1535 | 365 | 97.3% | 143 min | 0.00% | A+ |
| All Delta Air Lines on PHX–SLC | 1,706 | 90.1% | 81 min | 0.59% | A+ |
| All carriers on PHX–SLC | 5,779 | 83.0% | 61 min | 0.48% | B+ |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 1535 quarter by quarter
Quarter by quarter DL 1535 held fairly steady: 93.3% in Jul–Sep 2025, 96.7% in Oct–Dec 2025, 96.7% in Jan–Mar 2026, 97.8% in Apr–Jun 2026 and 100.0% in Jul–Sep 2026. A spread of 7 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Jul–Sep 202530 flights93.3%
- Oct–Dec 202592 flights96.7%
- Jan–Mar 202690 flights96.7%
- Apr–Jun 202691 flights97.8%
- Jul–Sep 202662 flights100.0%
Scale runs 85% to 100%.
By weekday, DL 1535 ranged from 92.3% on Thursday to 100.0% on Tuesday. With about 52 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 1535 runs when it is late
DL 1535 often beats the schedule: 168 of 365 completed flights, 46%, arrived 15 minutes or more early. The 10 late arrivals split 1 under half an hour, 4 between 30 and 60 minutes, and 5 an hour or more.
- 15+ min early168 flights46.0%
- Within 15 min187 flights51.2%
- 15–29 min late1 flights0.3%
- 30–59 min late4 flights1.1%
- 1–2 hours late1 flights0.3%
- 2+ hours late4 flights1.1%
Scale runs 0% to 100%.
Share of 365 completed flights by arrival against schedule.
Only 12 of 365 completed flights left 15 minutes late or more, too few to say how often the time is made up.
The worst days
Worst days for DL 1535
The latest arrival of the period was on 27 September 2025, 6 hours 52 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 |
|---|---|---|
| 27 September 2025 | 6 hours 52 minutes | Carrier |
| 19 March 2026 | 6 hours 2 minutes | Carrier |
| 20 September 2025 | 3 hours 14 minutes | Carrier |
| 9 April 2026 | 2 hours 35 minutes | Carrier |
| 13 February 2026 | 1 hour 38 minutes | Carrier |
Delay causes
Why DL 1535 runs late
Carrier accounts for 97% of the 1,427 delay minutes carriers reported here, and the remaining four split what is left.
- 97%Carrier
- 3%National Airspace System
The largest share of delay minutes, 97%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,381 of the 1,427 delay minutes reported here. The split is drawn from 1,427 delay minutes reported on DL 1535.
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
Badly late arrivals are rare here: only 1.4% 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.
The 507 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
Every one of the 365 flights under DL 1535 in the data flew PHX 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 1535
For a booking, DL 1535 has one of the better records a US domestic flight can show: 97.3% on time and 0.00% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- PHX to SLC, every carrier and departure
- SLC to PHX, the return direction
- Delta Air Lines 1431 on the same route87.8%
- Delta Air Lines 1738 on the same route86.4%
- Phoenix Sky Harbor International (PHX) 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
- How to read this site: grades, sample sizes, and honest caveats
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.