Carrier route record

DLSLC→MIA

Delta Air Lines · Salt Lake City to Miami

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 SLC to MIA earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 11 points better than the national rate of 77.6%. When something does go wrong the average delay runs about an hour. That rests on 364 flights, with a median arrival 8 minutes early.

Set against the rest of the country, Delta's SLC to MIA record is 11 points better than the US average of 77.6%. That gap is worth roughly 105 fewer late arrivals for every thousand flights.

On time

88.1%

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

84.5%

Every carrier on SLC to MIA, 776 flights

These figures cover 364 flights between July 2025 and June 2026. The median arrival is 8 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

Delta against every carrier on SLC to MIA

Delta flew 364 of the 776 flights on SLC to MIA, about 47% of it. Its 88.1% on time is 4 points better than the route as a whole, which runs 84.5%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Delta at 88.1% to American at 81.3%.

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 SLC to MIA
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines (this page)thin sample	364	88.1%	57 min	0.55%	A+
American Airlines	412	81.3%	66 min	1.21%	B

Flight by flight

Delta flight numbers on SLC to MIA

DL 204023:5088.1% · 364 flights

Departure window

When Delta runs best on this route

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 364 flights.

The overnight block holds up unusually well at 88.1% on time across 364 flights. Red-eyes fly into empty airspace and empty gates, and they are the first rotation of the aircraft's day rather than the last. The 8pm–5am window is the busiest, with 364 flights scheduled in it.

Across the year

Delta on SLC to MIA through the year

Darker means more delays. Figures are on-time percentages.May best, October worst

May is the best month on the calendar at 96.8% 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 31 flights.

Across the week, Sunday is the strongest day at 96.1% on time and Thursday the weakest at 78.8%. 17 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Delta runs late on this route

One category carries most of the weight here. Carrier accounts for 67% of the 2,432 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.

Carrier
67%
Late-arriving aircraft
20%
National Airspace System
13%

The largest share of delay minutes, 67%, 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 1,624 of the 2,432 delay minutes reported here. The split is drawn from 2,432 reported delay minutes.

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

Badly late arrivals are rare here: only 2.5% 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 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 76.5% on time across 364 flights, 12 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 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 SLC to MIA

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 88.1% 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