Route reliability record
MIA→SLC
Miami to Salt Lake City
- Flights
- 818
- Period
- September 2025 to August 2026
- Distance
- 2,088 mi
- Carriers
- 2
This route lands a B+, level with the national rate of 77.3%. Roughly one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 818 MIA to SLC flights, with a median arrival 6 minutes early.
Best time to fly MIA to SLC: a 8am–11am departure, ideally on a Wednesday. Flights in that window arrived on time 84.4% of the time and Wednesday flights 88.0%, against 77.3% for the route overall.
The US average over the same twelve months is 77.3%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
77.3%
Arrivals under 15 minutes late, of 812 completed flights
Avg delay
68 min
Across delayed arrivals only, not all flights
Cancelled
0.61%
National rate is 1.89%
Best carrier
American
75.1% on time across 454 flights
These figures cover 818 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
Which airline is most reliable on MIA to SLC
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 | 80.1% | 65 min | 0.55% | B+ |
| American Airlines | 454 | 75.1% | 70 min | 0.66% | B+ |
Flight by flight
Flights on MIA to SLC
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 15 points, against half a point between the best and worst carrier.
- 5am–8am255 flights84.2%
- 8am–11am162 flights84.4%
- 11am–2pm—
- 2pm–5pm4 flights—
- 5pm–8pm229 flights70.5%
- 8pm–5am168 flights69.6%
Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.
Book the morning departure. Flights leaving between 8am–11am arrive on time 84.4% of the time, against 69.6% 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 5am–8am window is the busiest, with 255 flights scheduled in it.
Explore
Filter MIA to SLC 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 MIA to SLC, the best departure window is 8am–11am at 84.4% on time and the worst is 8pm–5am at 69.6%, a wide gap of 14.8 points. All US flights leaving 8am–11am ran 83.9%.
- 5–8am84.2%
- 8–11am84.4%
- 11am–2pm—
- 2–5pm—
- 5–8pm70.5%
- 8pm–5am69.6%
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 27 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.
July is the worst month at 61.0% on time, 27 points below June, the best at 87.7%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. January was the busiest month here, with 93 flights.
Across the week, Wednesday is the strongest day at 88.0% on time and Sunday the weakest at 66.9%, a spread of 21 points.
Delay causes
Why this route gets delayed
Carrier accounts for 44% of the 12,000 delay minutes carriers reported here, and the remaining four split what is left.
- 44%Carrier
- 36%Late-arriving aircraft
- 17%National Airspace System
- 3%Extreme weather
- 0%Security
36% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 12,000 reported delay minutes here, that single category outweighs weather by 14 to one. The split is drawn from 12,473 reported delay minutes.
The largest share of delay minutes, 44%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 5,516 of the 12,000 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
7.5% 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 about 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 84.2% on time across 818 flights, 7 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 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 SLC 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 77.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 812 completed flights over 12 months sit behind that.
Common questions
MIA to SLC questions
How often is MIA to SLC delayed?
Roughly one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 22.7% of the 818 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
How reliable is MIA to SLC compared with the rest of the country?
77.3% of flights arrive on time here against a national 77.3%, a difference of half a point in its favour. That is worth a B+ on this site's grading scale.
What time of day has the fewest delays on MIA to SLC?
The 8am–11am departure window is the strongest at 84.4% on time. The 8pm–5am window is the weakest at 69.6%, 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 July delays on MIA to SLC?
July is the weakest month at 61.0% on time, compared with 87.7% in June. Across the year that is 27 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
- SLC to MIA — the return legseparate record
- Miami International (MIA) delay statistics
- Salt Lake City International (SLC) delay statistics
- Delta Air Lines on MIA to SLC80.1%
- American Airlines on MIA to SLC75.1%
- MIA to ATL, a related route74.2%
- DEN to SLC, a related route78.2%
- MIA to LGA, a related route67.4%
- Delta Air Lines on-time record80.1%
- American Airlines on-time record75.1%
- 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. MIA to SLC and SLC to MIA 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.