Carrier route record
DLPHL→SLC
Delta Air Lines · Philadelphia to Salt Lake City
- Flights
- 613
- Period
- July 2025 to June 2026
- Share of route
- 74%
- Carriers
- 2
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.
Delta on PHL to SLC lands a B, level with the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 613 flights, with a median arrival 2 minutes early.
The US average over the same twelve months is 77.6%, 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
78.3%
Arrivals under 15 minutes late, of 604 completed flights
Avg delay
59 min
Across delayed arrivals only, not all flights
Cancelled
1.31%
National rate is 1.81%
Whole route
76.9%
Every carrier on PHL to SLC, 833 flights
These figures cover 613 flights between July 2025 and June 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.
Carrier by carrier
Delta against every carrier on PHL to SLC
Delta flew 613 of the 833 flights on PHL to SLC, most of the route. Its 78.3% on time is about level with the route as a whole at 76.9%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Delta at 78.3% to American at 72.9%. 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) | 613 | 78.3% | 59 min | 1.31% | B |
| American Airlinesthin sample | 220 | 72.9% | 85 min | 5.45% | C− |
Flight by flight
Delta flight numbers on PHL to SLC
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 15 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am364 flights84.4%
- 8am–11am—
- 11am–2pm—
- 2pm–5pm—
- 5pm–8pm249 flights69.5%
- 8pm–5am—
Scale runs 60% 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 69.5% for the evening window. That is 15 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 364 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. July was the busiest month here, with 61 flights.
Across the week, Wednesday is the strongest day at 84.2% on time and Thursday the weakest at 70.1%. 14 points is a smaller lever than departure hour, but it is free.
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 7,713 reported delay minutes.
- 37%National Airspace System
- 32%Late-arriving aircraft
- 28%Carrier
- 3%Extreme weather
37% 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 2,884 minutes out of 7,713, against a national NAS share of 21%. The split is drawn from 7,713 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 84.4% on time here.
Cancellations sit at 1.31% against a national 1.81%, which is ordinary. Diversions add another 0.16%.
Connections and stage length
What a delay here costs
5.8% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says 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 82.9% on time across 613 flights, 5 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 5 points of difference.
One caution: this is a thin sample. 613 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. 613 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 78.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 604 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 SLC72.9%
- 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 7.04 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.