Route reliability record
SLC→MIA
Salt Lake City to Miami
- Flights
- 818
- Period
- September 2025 to August 2026
- Distance
- 2,088 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 77.3%. When something does go wrong the average delay runs a little over an hour. That rests on 818 SLC to MIA flights, with a median arrival 9 minutes early.
Best time to fly SLC to MIA: a 8pm–5am departure, ideally on a Wednesday. Flights in that window arrived on time 86.3% of the time and Wednesday flights 93.6%, against 84.2% 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 69 fewer late arrivals for every thousand flights.
Key figures
On time
84.2%
Arrivals under 15 minutes late, of 812 completed flights
Avg delay
75 min
Across delayed arrivals only, not all flights
Cancelled
0.61%
National rate is 1.89%
Best carrier
American
81.1% on time across 454 flights
These figures cover 818 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 MIA
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 Linesthin sample | 364 | 88.1% | 58 min | 0.55% | A+ |
| American Airlines | 454 | 81.1% | 83 min | 0.66% | B+ |
Flight by flight
Flights on SLC to MIA
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 matters more here than the choice of carrier. The gap between the best and worst window is 11 points, against half a point between the best and worst carrier.
- 5am–8am—
- 8am–11am—
- 11am–2pm91 flights75.8%
- 2pm–5pm71 flights76.1%
- 5pm–8pm—
- 8pm–5am656 flights86.3%
Scale runs 65% to 90%. Rows with fewer than 30 flights show a dash.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 75.8% on time against 86.3% for 8pm–5am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 8pm–5am window is the busiest, with 656 flights scheduled in it.
Explore
Filter SLC to MIA 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 MIA, the best departure window is 8pm–5am at 86.3% on time and the worst is 11am–2pm at 75.8%, a wide gap of 10.5 points. All US flights leaving 8pm–5am ran 70.1%.
- 5–8am—
- 8–11am—
- 11am–2pm75.8%
- 2–5pm76.1%
- 5–8pm—
- 8pm–5am86.3%
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 20 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.
September is the best month on the calendar at 93.3% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. January was the busiest month here, with 93 flights.
Across the week, Wednesday is the strongest day at 93.6% on time and Friday the weakest at 75.8%, a spread of 18 points.
Delay causes
Why this route gets delayed
Carrier accounts for 47% of the 9,572 delay minutes carriers reported here, and the remaining four split what is left.
- 47%Carrier
- 41%Late-arriving aircraft
- 11%National Airspace System
- 1%Security
- 0%Extreme weather
41% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 9,572 reported delay minutes here, that single category outweighs weather by 41 to one. The split is drawn from 9,572 reported delay minutes.
The largest share of delay minutes, 47%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 4,521 of the 9,572 delay minutes reported here.
Cancellations are rare at 0.61%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here actually costs
5.2% 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 a little over an hour, which a normal layover absorbs.
At 2,088 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 77.3% on time across 818 flights, 7 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 7 points of difference.
One caution: this is a thin sample. 818 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 MIA after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 818 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 84.2% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 812 completed flights over 12 months sit behind that.
Common questions
SLC to MIA questions
How often is SLC to MIA 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 15.8% of the 818 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
How reliable is SLC to MIA compared with the rest of the country?
84.2% 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 MIA?
The 8pm–5am departure window is the strongest at 86.3% on time. The 11am–2pm window is the weakest at 75.8%, 11 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 October delays on SLC to MIA?
October is the weakest month at 73.3% on time, compared with 93.3% in September. Across the year that is 20 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
- MIA to SLC — the return legseparate record
- Salt Lake City International (SLC) delay statistics
- Miami International (MIA) delay statistics
- Delta Air Lines on SLC to MIA88.1%
- American Airlines on SLC to MIA81.1%
- SLC to DEN, a related route79.0%
- ATL to MIA, a related route71.2%
- SLC to PHX, a related route83.5%
- Delta Air Lines on-time record88.1%
- American Airlines on-time record81.1%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Direction matters. SLC to MIA and MIA 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.