Flight number record
DL 2021
Delta Air Lines · Miami to Salt Lake City
- Route
- MIA → SLC
- Departs
- 07:00
- Flights
- 344
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 2021, check with Delta Air Lines.
DL 2021 lands a B+, 3 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 344 flights, with a median arrival 3 minutes early.
Key figures
On time
80.7%
Arrivals under 15 minutes late, of 342 completed flights
Avg delay
68 min
Across delayed arrivals only, not all flights
Cancelled
0.58%
National rate is 1.89%
1 hour+ late
5.3%
National rate is 8.3%
These figures cover 344 flights between September 2025 and August 2026. The median arrival is 3 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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Schedule
When DL 2021 flies
DL 2021 flies MIA to SLC without a single fixed slot. Its most common scheduled departure was 07:00, used on 61 of 344 flights, with 06:55 (54 flights) and 06:43 (47 flights) next.
- Departs 07:0061 flights17.7%
- Departs 06:5554 flights15.7%
- Departs 06:4347 flights13.7%
Scale runs 0% to 100%.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 07:00 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and DL 2021 runs 9 points worse at 80.7%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
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Against the route
DL 2021 next to MIA to SLC
Every carrier on MIA to SLC combined arrived on time 77.3% of the time across 818 flights, so DL 2021 is 3 points ahead of it. Across its whole network Delta Air Lines managed 81.1%, close to this flight's figure.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 2021thin sample | 344 | 80.7% | 68 min | 0.58% | B+ |
| All Delta Air Lines on MIA–SLCthin sample | 364 | 80.1% | 65 min | 0.55% | B+ |
| All carriers on MIA–SLC | 818 | 77.3% | 68 min | 0.61% | B+ |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 2021 quarter by quarter
DL 2021 did not run the same all year. Its best quarter was Apr–Jun 2026 at 86.8% on time and its weakest Oct–Dec 2025 at 68.1%, a swing of 19 points on roughly 69 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202530 flights80.0%
- Oct–Dec 202591 flights68.1%
- Jan–Mar 202690 flights86.4%
- Apr–Jun 202691 flights86.8%
- Jul–Sep 202642 flights83.3%
Scale runs 60% to 90%.
By weekday, DL 2021 did best on Tuesday at 89.8% on time and worst on Sunday at 65.3%. Each day rests on about 49 flights, so a gap of 25 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late DL 2021 runs when it is late
The 66 late arrivals split 28 under half an hour, 20 between 30 and 60 minutes, and 18 an hour or more.
- 15+ min early63 flights18.4%
- Within 15 min213 flights62.3%
- 15–29 min late28 flights8.2%
- 30–59 min late20 flights5.8%
- 1–2 hours late11 flights3.2%
- 2+ hours late7 flights2.0%
Scale runs 0% to 100%.
Share of 342 completed flights by arrival against schedule.
A late pushback is often recovered here: of 65 departures that left 15 minutes late or more, 20 still arrived on time. In the other direction, 21 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SLC.
The worst days
Worst days for DL 2021
The latest arrival of the period was on 7 June 2026, 10 hours 58 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. On four of the five worst days the largest share was filed as carrier-caused (crew, maintenance, fuelling, baggage).
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 7 June 2026 | 10 hours 58 minutes | Late-arriving aircraft |
| 4 July 2026 | 9 hours 9 minutes | Carrier |
| 26 November 2025 | 4 hours 30 minutes | Carrier |
| 5 July 2026 | 3 hours 46 minutes | Carrier |
| 16 November 2025 | 3 hours 36 minutes | Carrier |
Delay causes
Why DL 2021 runs late
Carrier accounts for 42% of the 4,467 delay minutes carriers reported here, and the remaining four split what is left.
- 42%Carrier
- 36%Late-arriving aircraft
- 19%National Airspace System
- 3%Extreme weather
36% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 4,467 reported delay minutes here, that single category outweighs weather by 14 to one. The split is drawn from 4,467 delay minutes reported on DL 2021.
Cancellations are rare at 0.58%, 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 routes
What a delay on this flight costs
5.3% 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 same number turns up on one other city pair in the data, including MSP to ATL (6), but none flew often enough under DL 2021 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to MIA to SLC only.
One caution: this is a thin sample. 344 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 DL 2021
For a booking, read DL 2021 as 80.7% on time with 0.58% cancelled over 344 flights. Those are rates from the past twelve months, not a forecast for any particular day.
Related
Where to go next
- MIA to SLC, every carrier and departure
- SLC to MIA, the return direction
- Miami International (MIA) delay statistics
- Salt Lake City International (SLC) delay statistics
- Delta Air Lines on-time record
- Every Delta Air Lines flight number with a record
- The most and least reliable flight numbers in the US
- Why the first flight of the morning is statistically safest
A flight number here means Delta Air Lines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.
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.