Route reliability record
SLC→PHL
Salt Lake City to Philadelphia
- Flights
- 805
- Period
- September 2025 to August 2026
- Distance
- 1,927 mi
- Carriers
- 2
This route lands a B, 7 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 an hour and a half on average. That rests on 805 SLC to PHL flights, with a median arrival 9 minutes early.
Best time to fly SLC to PHL: a 5pm–8pm departure, ideally on a Wednesday. Flights in that window arrived on time 89.3% of the time and Wednesday flights 93.5%, against 83.8% for the route overall.
Set against the rest of the country, this route's record is 7 points better than the US average of 77.3%. That gap is worth roughly 65 fewer late arrivals for every thousand flights.
Key figures
On time
83.8%
Arrivals under 15 minutes late, of 786 completed flights
Avg delay
87 min
Across delayed arrivals only, not all flights
Cancelled
1.99%
National rate is 1.89%
Best carrier
Delta
82.8% on time across 591 flights
These figures cover 805 flights between September 2025 and August 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.
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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 | 214 | 86.7% | 208 min | 4.67% | A− |
| Delta Air Lines | 591 | 82.8% | 55 min | 1.02% | 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.
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Departure window
The best time of day to leave
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 805 flights.
- 5am–8am116 flights87.2%
- 8am–11am115 flights84.7%
- 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.
Explore
Filter SLC to PHL by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On SLC to PHL, the best departure window is 5pm–8pm at 89.3% on time and the worst is 8pm–5am at 80.6%, a real gap of 8.7 points. All US flights leaving 5pm–8pm ran 68.0%.
- 5–8am87.2%
- 8–11am84.7%
- 11am–2pm83.3%
- 2–5pm—
- 5–8pm89.3%
- 8pm–5am80.6%
best all US flightsScale 60% to 95%. Cells under 30 flights show a dash.
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. March was the busiest month here, with 89 flights.
Across the week, Wednesday is the strongest day at 93.5% on time and Thursday the weakest at 78.4%, a spread of 15 points.
Delay causes
Why this route gets delayed
Carrier accounts for 59% of the 11,000 delay minutes carriers reported here, and the remaining four split what is left.
- 59%Carrier
- 21%National Airspace System
- 19%Late-arriving aircraft
- 1%Extreme weather
The largest share of delay minutes, 59%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 6,567 of the 11,000 delay minutes reported here. The split is drawn from 11,076 reported delay minutes.
Cancellations sit at 1.99% against a national 1.89%, which is ordinary. Diversions add another 0.37%.
Connections and stage length
What a delay here actually costs
5.1% 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 an hour and a half, 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 78.4% on time across 804 flights, 5 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 5 points of difference.
One caution: this is a thin sample. 805 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. 805 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 83.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 786 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 six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 16.2% of the 805 flights in this analysis, against 22.7% nationally. Delayed flights are late by an hour and a half on average.
How reliable is SLC to PHL compared with the rest of the country?
83.8% of flights arrive on time here against a national 77.3%, 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 5pm–8pm departure window is the strongest at 89.3% on time. The 8pm–5am window is the weakest at 80.6%, 9 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 PHL86.7%
- Delta Air Lines on SLC to PHL82.8%
- SLC to DEN, a related route79.0%
- ATL to PHL, a related route74.6%
- SLC to PHX, a related route83.5%
- American Airlines on-time record86.7%
- Delta Air Lines on-time record82.8%
- 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
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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.