Carrier route record
DLSLC→PHL
Delta Air Lines · Salt Lake City to Philadelphia
- Flights
- 591
- Period
- September 2025 to August 2026
- Share of route
- 73%
- Carriers
- 2
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on SLC to PHL lands a B, 6 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by about 55 minutes on average. That rests on 591 flights, with a median arrival 6 minutes early.
Set against the rest of the country, Delta's SLC to PHL record is 6 points better than the US average of 77.3%. That gap is worth roughly 55 fewer late arrivals for every thousand flights.
Key figures
On time
82.8%
Arrivals under 15 minutes late, of 583 completed flights
Avg delay
55 min
Across delayed arrivals only, not all flights
Cancelled
1.02%
National rate is 1.89%
Whole route
83.8%
Every carrier on SLC to PHL, 805 flights
These figures cover 591 flights between September 2025 and August 2026. The median arrival is 6 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 SLC to PHL
Delta flew 591 of the 805 flights on SLC to PHL, most of the route. Its 82.8% on time is about level with the route as a whole at 83.8%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from American at 86.7% to Delta at 82.8%. 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 |
|---|---|---|---|---|---|
| American Airlinesthin sample | 214 | 86.7% | 208 min | 4.67% | A− |
| Delta Air Lines (this page) | 591 | 82.8% | 55 min | 1.02% | B |
Flight by flight
Delta flight numbers on SLC to PHL
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 is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 591 flights.
- 5am–8am—
- 8am–11am17 flights—
- 11am–2pm328 flights83.3%
- 2pm–5pm—
- 5pm–8pm59 flights89.3%
- 8pm–5am187 flights80.6%
Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is the strongest at 89.3% on time. The full set of windows spans 9 points.
Across the year
Delta on SLC to PHL through the year
April is the best month on the calendar at 89.7% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. March was the busiest month here, with 58 flights.
Across the week, Wednesday is the strongest day at 91.0% on time and Thursday the weakest at 76.0%, a spread of 15 points.
Arrival by arrival
How late Delta on SLC to PHL runs when it is late
Delta on SLC to PHL often beats the schedule: 173 of 583 completed flights, 30%, arrived 15 minutes or more early. The 100 late arrivals split 41 under half an hour, 34 between 30 and 60 minutes, and 25 an hour or more.
- 15+ min early173 flights29.7%
- Within 15 min310 flights53.2%
- 15–29 min late41 flights7.0%
- 30–59 min late34 flights5.8%
- 1–2 hours late15 flights2.6%
- 2+ hours late10 flights1.7%
Scale runs 0% to 100%.
Share of 583 completed flights by arrival against schedule.
18 of 78 late departures made up the time and arrived on time, 23% of them. In the other direction, 40 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 PHL.
The worst days
Worst days for Delta on SLC to PHL
The latest arrival of the period was on 22 March 2026, 6 hours 13 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 |
|---|---|---|
| 22 March 2026 | 6 hours 13 minutes | Carrier |
| 15 November 2025 | 3 hours 39 minutes | Late-arriving aircraft |
| 21 July 2026 | 3 hours 37 minutes | National Airspace System |
| 13 February 2026 | 3 hours 7 minutes | Carrier |
| 1 January 2026 | 2 hours 59 minutes | Carrier |
Delay causes
Why Delta runs late on this route
Carrier accounts for 43% of the 5,457 delay minutes carriers reported here, and the remaining four split what is left.
- 43%Carrier
- 40%National Airspace System
- 16%Late-arriving aircraft
- 1%Extreme weather
The largest share of delay minutes, 43%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,355 of the 5,457 delay minutes reported here. The split is drawn from 5,457 reported delay minutes.
40% 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 2,167 minutes out of 5,457, against a national NAS share of 21%.
Cancellations sit at 1.02% against a national 1.89%, which is ordinary. Diversions add another 0.34%.
Connections and stage length
What a delay here costs
Badly late arrivals are rare here: only 4.3% 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.
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 79.6% on time across 591 flights, 3 points below 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 SLC to PHL
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 82.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 583 completed flights over 12 months sit behind that.
Related
Where to go next
- SLC to PHL, every carrier
- Delta on PHL to SLC, the return leg
- American Airlines on SLC to PHL86.7%
- Delta Air Lines network-wide record
- Salt Lake City International (SLC) delay statistics
- Philadelphia International (PHL) 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.