Route reliability record
SLC→PHL
Salt Lake City to Philadelphia
- Flights
- 833
- Period
- July 2025 to June 2026
- Distance
- 1,927 mi
- Carriers
- 2
This route earns a B. More than four flights in five arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 77.6%. When something does go wrong the average delay runs a little over an hour. That rests on 833 SLC to PHL flights, with a median arrival 9 minutes early.
Best time to fly SLC to PHL: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 95.1% of the time and Saturday flights 90.7%, against 84.7% for the route overall.
Set against the rest of the country, this route's record is 7 points better than the US average of 77.6%. That gap is worth roughly 71 fewer late arrivals for every thousand flights.
Key figures
On time
84.7%
Arrivals under 15 minutes late, of 809 completed flights
Avg delay
74 min
Across delayed arrivals only, not all flights
Cancelled
2.40%
National rate is 1.81%
Best carrier
Delta
82.9% on time across 613 flights
These figures cover 833 flights between July 2025 and June 2026. The median arrival is 9 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
Which airline is most reliable on SLC to PHL
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 | 220 | 89.8% | 198 min | 5.91% | A− |
| Delta Air Lines | 613 | 82.9% | 49 min | 1.14% | B |
Flight by flight
Flights on SLC to PHL
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
Departure window
The best time of day to leave
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–8am86 flights95.1%
- 8am–11am120 flights87.9%
- 11am–2pm323 flights83.6%
- 2pm–5pm—
- 5pm–8pm59 flights89.3%
- 8pm–5am245 flights79.8%
Scale runs 70% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 95.1% of the time, against 79.8% for the overnight 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 11am–2pm window is the busiest, with 323 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 19 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
May is the best month on the calendar at 91.4% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. July was the busiest month here, with 92 flights.
Across the week, Saturday is the strongest day at 90.7% on time and Thursday the weakest at 77.8%. 13 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Carrier accounts for 57% of the 9,168 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 57%Carrier
- 24%Late-arriving aircraft
- 18%National Airspace System
- 0%Extreme weather
The largest share of delay minutes, 57%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 5,225 of the 9,168 delay minutes reported here. The split is drawn from 9,168 reported delay minutes.
Cancellations sit at 2.40% against a national 1.81%, which is ordinary. Diversions add another 0.48%.
Connections and stage length
What a delay here actually costs
Badly late arrivals are rare here: only 4.2% land an hour or more behind schedule, against 8.1% 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 76.9% on time across 833 flights, 8 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 8 points of difference.
One caution: this is a thin sample. 833 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.
Work out the risk of missing a connection in PHL after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 833 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 84.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 809 completed flights over 12 months sit behind that.
Common questions
SLC to PHL questions
How often is SLC to PHL delayed?
About one flight in seven arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 15.3% of the 833 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
How reliable is SLC to PHL compared with the rest of the country?
84.7% of flights arrive on time here against a national 77.6%, a difference of 7 points in its favour. That is worth a B on this site's grading scale.
What time of day has the fewest delays on SLC to PHL?
The 5am–8am departure window is the strongest at 95.1% on time. The 8pm–5am window is the weakest at 79.8%, 15 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are November delays on SLC to PHL?
November is the weakest month at 72.7% on time, compared with 91.4% in May. Across the year that is 19 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- PHL to SLC — the return legseparate record
- Salt Lake City International (SLC) delay statistics
- Philadelphia International (PHL) delay statistics
- American Airlines on SLC to PHL89.8%
- Delta Air Lines on SLC to PHL82.9%
- SLC to DEN, a related route77.8%
- ATL to PHL, a related route74.9%
- SLC to PHX, a related route83.9%
- American Airlines on-time record89.8%
- Delta Air Lines on-time record82.9%
- 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
Direction matters. SLC to PHL and PHL to SLC are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.