Flight profile · Delta Air Lines
DL1535
Phoenix (PHX) to Salt Lake City (SLC) · scheduled 6:00 AM – 8:50 AM
How DL1535 performs
785 operations, June 2024 – July 2026.
DL1535 arrived on time 96.8% of the time, against 84.5% for all PHX → SLC flights, so this departure is 12.3 percentage points better than the route as a whole. Against Delta Air Lines’ own flights on this route it is 7.4 points better.
Source: US DOT Bureau of Transportation Statistics · 785 operations, June 2024 – July 2026 · If DL1535 is cancelled or significantly changed, DOT’s automatic refund rule may entitle you to your money back. The refund checker walks through eligibility.
What stands out
How DL1535 compares to other flight numbers, not just to itself.
This flight stays close to typical even on its worst days, a smaller gap than 99% of 11,788 comparable flight numbers.
A typical arrival is 13 min early, and the worst tenth are only 12 minutes worse than that.
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026 · The one thing about this specific departure that ranks most extreme against every other published flight number, out of everything FlyerIntel checks — shown only when something clears a real statistical bar, not for every flight.
Where DL1535 is right now
A live reading, only if you ask for it. It is not part of the reliability record above.
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Against the rest of the route
| Flight or route | On time | Cancelled | Median delay | Severe | Flights |
|---|---|---|---|---|---|
| DL1535 | 96.8% | 0.38% | -13 min | 1.8% | 785 |
| Delta Air Lines on PHX → SLC | 89.4% | 0.43% | -11 min | 3.9% | 5,332 |
| All PHX → SLC flights | 84.5% | 0.36% | -8 min | 4.6% | 17,759 |
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026
Why DL1535 runs late
Where US DOT attributed the delay minutes on this flight.
crew, maintenance, boarding and fueling, all within the carrier’s control
weather severe enough to stop this flight specifically
airspace and airport capacity, including weather-driven flow control
the inbound aircraft was late, so this flight started late
Share of the delay minutes US DOT attributed to each cause for DL1535 on PHX → SLC. Only delays of 15 minutes or more are attributed.
Source: US DOT Bureau of Transportation Statistics · Data covering June 2024 – July 2026
Does a late aircraft delay this flight?
How often the plane that flies DL1535 comes in late, and what that does to the departure.
DL1535 is usually the aircraft’s first flight of the day: the schedule gives it a median of 6.5 hours on the ground at PHX, so its “inbound” is mostly the aircraft’s arrival the evening before.
When the aircraft came in 15 or more minutes late, DL1535 pushed back an average of 3 minutes late; when it came in on time or early, an average of 1 minute early.
Each departure is matched to the flight the same aircraft flew into PHX just before it, using the tail number in the DOT file, 754 of 782 departures in all. A departure is left out when that flight is unknown, was cancelled or diverted, or the aircraft had sat for more than 12 hours. A flight the airline cancelled never left and is not in the count, and one flown by a substitute aircraft is matched to the aircraft that flew it, not to the one first planned.
Against the network at the same turn length
| Share of departures | Inbound landed 15+ late | Left 15+ late after a late inbound | Left 15+ late after an on-time inbound |
|---|---|---|---|
| DL1535 | 19% | 6% | 3% |
| Network, same turn | 29% | 12% | 9% |
A night on the ground absorbs most of a late arrival, so a late inbound matters far less on a turn this long than on a same-day one.
The network row is every flight with a scheduled turn of 6 hours or more, usually overnight. How often DL1535’s aircraft landed 15 or more minutes late is lower than the network’s and, once the aircraft was late, how often DL1535 left 15 or more minutes late is lower than the network’s.
More: Which Flight Numbers Pay for a Late Aircraft lists the flight numbers that pass a late aircraft on.
Source: US DOT Bureau of Transportation Statistics · Data covering June 2024 – July 2026
From pushback to gate
When it leaves PHX late, does that still matter by the time it reaches SLC?
DL1535 pushes back an average of 1.3 minutes late and reaches the gate at SLC an average of 6.4 minutes early. The 7.7 minutes between those two figures are slack the published schedule already carries, which is why a late pushback on this flight does not reliably become a late arrival. Its 14.1 minutes on the taxiways at PHX is about what any departure from the airport in that hour spends.
On arrival at SLC, DL1535 spends 6.8 min taxiing from touchdown to the gate — ground time a connecting passenger sits through before they can even leave the aircraft, on top of however late the flight itself ran. That is about what any arrival at SLC spends on the ground before reaching the gate.
Departure delay is averaged over every pushback and arrival delay over every completed arrival, so the two counts differ by the flights that never reached SLC. Taxi-out is gate to wheels up and sits inside the scheduled block rather than on top of it; the comparison is 25,597 departures from PHX scheduled in the clock hour DL1535 most often leaves in. Taxi-in is landing to gate, compared against every arrival FlyerIntel has on file at SLC (355,118 flights), not just DL1535’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026
The hour it leaves PHX
Part of any flight’s record belongs to the clock rather than to the flight. DL1535 has one departure time, so this is what that time is worth.
On-time arrival rate. 25,597 departures from PHX are scheduled in the 6 AM–7 AM hour over the period, against 598,518 across the whole day.
DL1535 is scheduled out of PHX at 6:00 AM, in the 6 AM–7 AM bank. Departures from PHX in that hour arrive on time 94.0% of the time against 80.3% across the airport’s whole day — the slot alone is worth 13.7 points better before anything about this particular flight is considered.
The two airport figures cover every departure from PHX to every destination, so they describe the slot rather than this journey — the like-for-like comparison against the route is above. Hours are scheduled local, and a number whose schedule moved between banks inside the period has no single hour and is not described here at all. Why the hour matters.
Source: FlyerIntel analysis of US DOT BTS data · June 2024 – July 2026 · Hours below 120 departures are not scored.
Other routes DL1535 has flown
A flight number is a slot in a schedule, and carriers reassign it. These are the other city pairs this number served in the analysis period.
| Route | Operated | Flights | On time |
|---|---|---|---|
| CLE→MSP Cleveland to Minneapolis | May 7, 2024 – June 6, 2024 | 31 | — |
| ORF→ATL Norfolk to Atlanta | January 8, 2024 – May 6, 2024 | 105 | 91.4% |
| ATL→ORF Atlanta to Norfolk | January 15, 2024 – May 6, 2024 | 90 | 83.3% |
| ATL→IND Atlanta to Indianapolis | January 13, 2024 – March 9, 2024 | 10 | — |
| IND→ATL Indianapolis to Atlanta | January 13, 2024 – March 9, 2024 | 10 | — |
| ALB→DTW Albany to Detroit | January 1–7, 2024 | 7 | — |
| MSP→JFK Minneapolis to New York | November 5, 2023 – December 15, 2023 | 41 | — |
Because the same number has served different journeys, the statistics above describe only the route DL1535 currently operates. Blending them would produce an average of two different flights.
When it goes wrong
The average describes a usual day. This is the day that ruins a connection.
1 min early
against a median of 13 min early
Percentiles over 785 operations; cancelled and diverted flights are counted separately.
Source: US DOT Bureau of Transportation Statistics · Data covering June 2024 – July 2026
Other flights on this route
Same airports, same journey, different odds of arriving on time.
| Flight | Airline | On time | Median arrival | Operations |
|---|---|---|---|---|
| DL1535 this flight | Delta Air Lines | 96.8% | 13 min early | 785 |
| DL1447 | Delta Air Lines | 93.9% | 14 min early | 623 |
| F91440 | Frontier Airlines | 90.5% | 13 min early | 760 |
| DL1431 | Delta Air Lines | 88.3% | 10 min early | 750 |
Every departure listed carries at least 600 operations, so the comparison is between figures that mean something. DL1535 is placed in the same ordering rather than left out of it; the rows around it are the most punctual departures on the route, not all of them, so this is a comparison and not a rank. Schedules change; confirm the departure still operates before booking around this.
Data and methodology
Calculated by FlyerIntel from 785 records of DL1535 operating PHX → SLC, published by the US DOT Bureau of Transportation Statistics. A flight counts as delayed when it arrives 15 or more minutes after schedule. Cancelled and diverted flights are excluded from the on-time rate and reported separately. Flight numbers are resolved as carrier plus number plus route, because the same number serves different routes over time.
Full methodology · Data sources · Report a problem
Related research: Most and Least Reliable Flight Numbers · The Delay You Inherit · Making Up Time in the Air
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