Carrier route record
DLPHL→SLC
Delta Air Lines · Philadelphia to Salt Lake City
- Flights
- 591
- Period
- September 2025 to August 2026
- Share of route
- 74%
- Carriers
- 2
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on PHL to SLC lands a B, 2 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 591 flights, with a median arrival 2 minutes early.
The US average over the same twelve months is 77.3%, so there is little to separate Delta on PHL to SLC from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
79.6%
Arrivals under 15 minutes late, of 584 completed flights
Avg delay
66 min
Across delayed arrivals only, not all flights
Cancelled
1.18%
National rate is 1.89%
Whole route
78.4%
Every carrier on PHL to SLC, 804 flights
These figures cover 591 flights between September 2025 and August 2026. The median arrival is 2 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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Carrier by carrier
Delta against every carrier on PHL to SLC
Delta flew 591 of the 804 flights on PHL to SLC, most of the route. Its 79.6% on time is about level with the route as a whole at 78.4%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Delta at 79.6% to American at 74.9%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines (this page) | 591 | 79.6% | 66 min | 1.18% | B |
| American Airlinesthin sample | 213 | 74.9% | 132 min | 4.23% | C− |
Flight by flight
Delta flight numbers on PHL to SLC
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.
Departure window
When Delta runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 13 points, against half a point between the best and worst carrier.
- 5am–8am365 flights84.4%
- 8am–11am—
- 11am–2pm—
- 2pm–5pm—
- 5pm–8pm226 flights71.9%
- 8pm–5am—
Scale runs 65% to 90%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 84.4% of the time, against 71.9% for the evening window. That is 13 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 365 flights scheduled in it.
Across the year
Delta on PHL to SLC through the year
December is the weak month at 43.8% on time, against 94.8% in April. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. March was the busiest month here, with 58 flights.
Across the week, Tuesday is the strongest day at 85.5% on time and Thursday the weakest at 69.8%, a spread of 16 points.
Arrival by arrival
How late Delta on PHL to SLC runs when it is late
The 119 late arrivals split 57 under half an hour, 24 between 30 and 60 minutes, and 38 an hour or more.
- 15+ min early123 flights21.1%
- Within 15 min342 flights58.6%
- 15–29 min late57 flights9.8%
- 30–59 min late24 flights4.1%
- 1–2 hours late21 flights3.6%
- 2+ hours late17 flights2.9%
Scale runs 0% to 100%.
Share of 584 completed flights by arrival against schedule.
26 of 97 late departures made up the time and arrived on time, 27% of them. In the other direction, 48 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SLC.
The worst days
Worst days for Delta on PHL to SLC
The latest arrival of the period was on 14 June 2026, 6 hours 5 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. On three of the five worst days the largest share was filed as carrier-caused (crew, maintenance, fuelling, baggage).
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 14 June 2026 | 6 hours 5 minutes | National Airspace System |
| 23 March 2026 | 6 hours 3 minutes | Late-arriving aircraft |
| 29 July 2026 | 5 hours 42 minutes | Carrier |
| 23 October 2025 | 5 hours 29 minutes | Carrier |
| 1 July 2026 | 4 hours 29 minutes | Carrier |
Delay causes
Why Delta runs late on this route
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 7,828 reported delay minutes.
- 41%Carrier
- 32%National Airspace System
- 25%Late-arriving aircraft
- 3%Extreme weather
The largest share of delay minutes, 41%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 3,174 of the 7,828 delay minutes reported here. The split is drawn from 7,828 reported delay minutes.
32% 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 2,507 minutes out of 7,828, against a national NAS share of 21%.
Cancellations sit at 1.18% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and stage length
What a delay here costs
6.5% 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.
At 1,927 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 82.8% on time across 591 flights, 3 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 3 points of difference.
One caution: this is a thin sample. 591 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 Delta on PHL to SLC
Put together: treat all of this as provisional. 591 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 79.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 584 completed flights over 12 months sit behind that.
Related
Where to go next
- PHL to SLC, every carrier
- Delta on SLC to PHL, the return leg
- American Airlines on PHL to SLC74.9%
- Delta Air Lines network-wide record
- Philadelphia International (PHL) delay statistics
- Salt Lake City International (SLC) delay statistics
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
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.