Carrier route record

DLMIA→SLC

Delta Air Lines · Miami to Salt Lake City

Flights: 364
Period: July 2025 to June 2026
Share of route: 47%
Carriers: 2

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.

Delta on MIA to SLC lands a B+, about a point worse than the national rate of 77.6%. About one flight in four 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 364 flights, with a median arrival 1 minute early.

The US average over the same twelve months is 77.6%, so there is little to separate Delta on MIA to SLC from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

76.5%

Arrivals under 15 minutes late, of 362 completed flights

Avg delay

57 min

Across delayed arrivals only, not all flights

Cancelled

0.55%

National rate is 1.81%

Whole route

76.7%

Every carrier on MIA to SLC, 776 flights

These figures cover 364 flights between July 2025 and June 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.

Carrier by carrier

Delta against every carrier on MIA to SLC

Delta flew 364 of the 776 flights on MIA to SLC, about 47% of it. Its 76.5% on time is about level with the route as a whole at 76.7%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from American at 76.8% to Delta at 76.5%.

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.

On-time performance by carrier on MIA to SLC
Airline	Flights	On time	Avg delay	Cancelled	Grade
American Airlines	412	76.8%	67 min	1.21%	B
Delta Air Lines (this page)thin sample	364	76.5%	57 min	0.55%	B+

Flight by flight

Delta flight numbers on MIA to SLC

DL 202107:0076.5% · 364 flights

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 20 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–8am193 flights85.9%
8am–11am—
11am–2pm—
2pm–5pm4 flights—
5pm–8pm167 flights65.9%
8pm–5am—

Scale runs 55% to 90%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 85.9% of the time, against 65.9% for the evening window. That is 20 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 193 flights scheduled in it.

Across the year

Delta on MIA to SLC through the year

Darker means more delays. Figures are on-time percentages.June best, July worst

July is the worst month at 51.6% on time, 45 points below June, the best at 96.7%. 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 31 flights.

Across the week, Tuesday is the strongest day at 86.5% on time and Sunday the weakest at 65.4%. 21 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 4,871 reported delay minutes.

Late-arriving aircraft
41%
Carrier
31%
National Airspace System
24%
Extreme weather
4%

41% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 4,871 reported delay minutes here, that single category outweighs weather by 11 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 4,871 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 85.9% on time here.

Cancellations are rare at 0.55%, below the national 1.81% 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 costs

5.5% 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 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 88.1% on time across 364 flights, 12 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 12 points of difference.

One caution: this is a thin sample. 364 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 MIA to SLC

Put together: treat all of this as provisional. 364 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 76.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 362 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures